Virginia Tech Class of 70. WA4DUS from 1961 until 1977. N4DJ since 1977.
Operated from FG0CXV/FS7 in October/November 1976.
Rig is Elecraft K3 and Drake L7 amplifier.
N4DJ HOME PAGE
DXCC DXCC/CW WAS WAC
For thirty years my main rig was a Drake T4XC transmitter, R4C receiver and a Drake L7 amplifier. The old standby rig was a Johnson Viking Ranger II transmitter with a Drake 2B receiver and a homebrew linear amplifier that uses a pair of 813s.
In April 2007 I decided to replace the Drake Twins with a Ten Tec OMNI VI which was factory upgraded to be equivalent to the OMNI VI Plus. I am planning to add some Sherwood mods to the R4C. I have the kits and hope to do the work soon.
In 2012, I decided to upgrade again. The new rig is an Elecraft K3. I have the controls configured very much like the OMNI VI. Having a subreceiver identical to the main receiver seems to be a great thing for 160 meters.
For mobile I use an Icom 706 with a Hustler antenna. At last count I had worked 93 countries mobile.
The Antennas (November 2001 through April 2011)
The 160 antenna was an inverted L. Overall length was extended past a quarter wavelength to bring the impedance up to 50 ohms resistive plus some inductive reactance. I used about 200 MMF of capacitance between the coax feedline and the antenna to cancel the inductive reactance resulting in a near perfect 50 ohm load to the coax.
The 80 meter antenna was a full size half square. It may be the best antenna I have ever had. It was arranged to be broadside to Europe. I could usually work Europe in the afternoons as early as a lot of the W1s! The only other antenna comparable to it is my full size 4 element 20 meter monoband yagi. However, it is in it's original carton in my garage.
40, 20 and 10 meters was covered by three halfwave dipoles connected to the same feedline using small PVC pipe as spacers. KG4ZYY, Richard gave me this idea.
For 17 meters I used a separate dipole. For contest operations I would drop the 17 meter dipole and replace it with a 15 meter dipole.
Click on my "Antenna Projects " below. It has pictures of various antennas and somewhat current projects. I also have a page dedicated to the Half Square antennas I have built (80 and160 meters).
I operated from my Dandy Point location for almost exactly 8 years and 5 months with only wire antennas. Thanks to computer logging it was easy to get a summary of my results with these antennas.
Total QSOs 15,354
Countries by Band
Most DX was worked with about 700 watts output, but I also worked all 50 states running QRP.
My best contest results were: 1.6 million points in the 2010 CQ WW CW contest with over 100 countries on 40, 20 and 15 meters and 1.5 millionpoints in the 2011 ARRL CW DX contest.
ANTENNAS 2011 to 2014
In September 2011, I started up at my new New Kent County location. Along with the wire antennas I had planned to have my 20 meter monobander back in action. It was last up at my first Dandy Point QTH in 1992 on a 70 foot Rohn 45 foldover tower on a Universal self supporting aluminum tower like I had in the 70's and 80's. After three years, I had not gotten around to the tower and made a decision that since I had been doing so well with only wire antennas, I would just stick with them.
I put the 80 meter half square up, first pointed to Japan to see how that would work. The I took it down and rotated it to Europe. I also put up my dipoles for 40, 20 and 10 meters. Right off the bat I beat last years CQWW CW Score with 1474 QSOs for 2,512,036 points and working 100+ countries on 40, 20 ,15 and 10 meters. I thought "The antennas are working good at my new location". That got me started thinking that maybe I did not need the Yagi.
I also installed a bent half square up for 160 meters. A little late for 2011-20012 season's 160 contests, but ready for next season!In addition to the transmitting antennas, I decided to try to make a Beverage work. I ended up with two BOGs or Beverages on the ground and one conventional Beverage. I had a 220 foot BOG pointed North East a 480 foot BOG pointed West and a Beverage about 250 ft long and 6 ft high pointed South. These receiving antennas were just fantastic. In almost all cases on 160 through 40 meters I listended only on the Beverages. Having a K3, I was able to put the South Beverage on the subreceiver and had a switch so that I could switch the other two back and forth on the main receiver. I had it set up so I could be running Europe on the NE BOG and if a station from some South America called I would hear him in my right ear! That worked great, especially in 160 meter contests. See my Beverage Page.
ANTENNAS 2014 to present
I started up operations in Williamsburg, Va in May 2014. I am using an end fed wire, essentially a 160 Meter Inverted L. This is what I have used very successfully on 160 meters in the past and with an L network tuner I can load it on all bands. I also hope to put up a dipole for 20 and /or 15 meters. It all depends on how the Inverted L works on those bands. For contesting, having an antenna with a major lobe into Europe is a must. So far the antenna is working well.
I also am an amateur photographer and will have some of my photographs on various picture pages. One of my photos was the cover of CQ Magazine for July 1977.
Contesting Some of the highlights of N4DJ/WA4DUS contesting over the past 49 years.
Top Band at N4DJ Pictures of antennas and station 1964 to 2011
OSCAR from FS7 This is an historical note about W4PRO, W4GSM and N4DJ (then WA4DUS) DX pedition to FS7 in 1976. We were FG0CXV/FS7. Did we work you?
Recent Satellite operations
TEN METER BEAM Information on a two element 10 meter beam I built.
Virginia Tech Amateur Radio Association Pictures from 1966 through 1970
Antenna Projects Recent antenna projects here, as well as some past antennas.
Half Square Antennas 160 and 80 Meter Half Square Design
Baseball & Softball Pictures
My son Chip (KC4RKO) finished his first feature film as a writer and director. Check out the website for his film "In The Pines" Chips new film In The Pines
Visitors since 8 September 2008
2015 N4DJ station Elecraft K3 and Drake L7 Inverted L for 160 plus dipoles. One short Beverage so far.
80 Meter Half Square Antennas by N4DJ
In order to work DX you need an antenna with low angle radiation. The more power you can focus at the low angles the better your DX results will be.
The problem with horizontal antennas on 80 meters is that you have to have them really high to get low angle radiation. An antenna only a half wavelength high has most of its radiation at 30 degrees. Having the maximum radiation at 15 degrees would be much better. With a 80 Meter dipole to even get the maximum down to 30 degrees you need the dipole up at about 130 feet. Below are the elevation plots of a 80 meter dipole at 60 and 120 feet above ground. The green dot is at an elevation angle of 15 degrees. All gains are referenced to an isotropic antenna. Note that the antenna at 120 feet has almost 6 dB more gain than the one at 60 feet. Actually these plots show 5.5 dB. Even though most of us think of 120 feet as really high, on 80 it is like having a 10 meter dipole up at only at 16 feet! 120 feet is just not very high in terms of a wavelength when the wavelength is in the neighborhood of 260 or 270 feet.
Notice the gain of the 60 foot high dipole is negative - .86 dBi. I like to reference everything I do to dBi if possible. 0 dBi being the signal level if all your power was being radiated equally in all directions. The gain of the 120 foot dipole is a respectible 4.7 dBi.
Vetrical antennas, in general, are not dependent on height above ground to obtain a low angle of radiation. The quality of the ground under and around the vertical is important. Another factor we need to be concerned with in the performance of a vertical is that of a radial system to reduce the ground loss. In most verticals the ground makes up half the antenna and unless you have a good radial system you can lose a lot of your power in the ground resistance. One way around this is to use a vertical antenna that does not require the ground to make up half the antenna. While a 60 foot vertical on 80 requires a good radial system, a full size vertical dipole does not. Of course, a full size vertical dipole requires a support over 120 foot high! I have found, what I think is a better way to go on the low bands.
A Half Square antenna solves many of the problems associated with needing excessive height and excessive radial sysyems on 80 meters. While full size half squares on 80 requires about 75 feet in height, bent versions can easily be constructed with minimal reduction in gain from the full size version and still be better than a dipole at 60 or 120 feet. Below are elevation plots of a full size 80 meter half square with the top at 75 feet and a slightly bent half square with its top at only 55 feet.
The gain at 15 degrees for the full size half square (top at 75 feet) is 6.2 dBi, while the bent half square (only 55 feet high) is 5.8 dBi. The bent half square is only about .6 dB down from the full size version.
Gain of full size half square vs bent half square:
The next plot shows how it compares to a 80 meter dipole at 120 feet.
Not too bad! At an elevation angle of 15 degrees the bent half square is actually better than the dipole at 130 feet!
Since 120 feet is a bit high for most of us, I compared it to a more reasonable height of only 60 feet. See the next plot below:
At an elevation angle of 15 degrees, the bent half square (55 foot high maximum) has a gain of 5.86 dBi. The dipole at 60 feet has a gain of -0.83 at the same angle. The bent half square is more than 6 dB better!
The EZ NEC diagram of the bent antenna is shown with all the wires numbered.
The lengths for the wires are as follows:
Wires 1 & 6: 15 ft
Wires 2 & 6: 50 ft
Wires 3 and 4: 65 ft
The EZNEC wiring table as used in modeling my N4DJ Half Square
I used this antenna on 80 meters for just over 7 years. The maximum height was 55 feet. The ends were only bent in about 15 feet. In my case hanging the half square between two pine trees allowed me to have an antenna that was probably better for DX than a dipole at 120 feet. Performance of this antenna was exceptional. I worked over 140 countries with it on 80 meters. I am not 100% sure, but I think it should out perform a "4 Square" array in two directions. However the 4 square has the advantage of being unidirectional and being able to switch the pattern. It is also a lot more complicated and involves extensive radial systems.
How do these antennas stack up against a full size quarter wave vertical on 80 meters? Well I always thought that a full size vertical would be a great antenna. I have had a couple of 70 foot towers shunt fed for 80 meters and also with extensions out the top to get me to a physical height of about 108 to 110 feet. With some top loading I had about the equivalent of a quarter wave vertical on 160. I have also operated with 135 foot verticals held up by balloons. These full size verticals were good antennas at the time. However, I think it is safe to say that a good quarter wave vertical will probably have a gain less than 1 dBi , if that high. Of course the pattern should be omni directional. That is both good and bad. Good because it covers all directions and no nulls in the pattern and bad because it covers all directions with no nuls in the pattern!
The ultimate in vertical performance would be if it were over salt water, so I will include a plot for this case. Note below that the gain at 15 degrees is 5.02 dBi.
Now lets compare the N4DJ as built half square to this "ultimate" vertical over seawater.
Note that until the elevation angle gets down to 9 degrees, the half square is still has the most gain.
Since a full size quarter wave vertical is beyond the reach of most of us, I will do a more realistic comparison to a full size vertical using four elevated radials over very good ground.
In this case the full size vertical has a maximum gain of 2.49 dBi at 17 degrees versus the 5.94 dBi of the severely bent half square. It is clear that the bent half square should be 3 dB better than the full size vertical, even more if the ground is not so good.
This is the plot of my 80 meter Half Square. The favored directions are shown in green.
The SWR curve should also be noted. On 80 meters the SWR rises quite fast either side of resonance.
With the feed at the top corner, a symmertical antenna can be operated at any frequency in the band.
Although the 2:1 SWR bandwidth is only about 80 kHz, operating with a high SWR does not seem to affect the performance at all. If the antenna were to be fed at the bottom of one of the vertical legs, such would not be the case.
No doubt that arrays of two or more full size quarter wave verticals will out perform the bent half sqaure, but the effort and expense to install such an array is usually beyond the reach of most of us. The cost of a bent half sqaure is essentially the cost of 260 ft of wire and a few insulators, providing of course you have a couple convinently placed tall trees! Another advantage of the half square is that it can be fed directly with coax. On my 80 meter half square I usually add and remove short extensions to the bottom of mine prior to a DX contest to adjust it for CW or SSB. For CW a I add a few feet to the lower horizontal wires to get the best SWR around 3525 and remove it for SSB so that it is resonant around 3795. I have found that it works just as well on 3795 when tuned for 3525, the SWR at the amplifier is just higher than most of us would like. However on 80 meters the coax loss is very low to start with and the additional loss due to operating off frequency with a high SWR (in my case) is about 1 dB. I figure that brings my 80 meter half square down to being only as good as a dipole at 120 feet! I can live with that.
A couple last notes. I just put this antenna up at my new location. Thanks to a suggestion from Ted, W3TB, I am working on a variation to the design that will allow switching the pattern approximately 90 degrees. This will require an additional 195 foot of wire and a switch. I also plan to put up a "bent" 160 version and there is also the possibility of combining an 80 meter version with a 160 version with some common wire and a common feedline.
I also was fortunate to attend a forum by W3LPL at the Virginia Beach Hamfest/Roanoke Division convention September 17, 2011. He has a two element Quad with the bottom at about 100 feet. I plan to post an EZNEC comparison of the two antennas shortly. Preliminary modeling with EZNEC indicates that my Half Square may be 5.7 dB down (at an elevation angle of 15 degrees) from a Quad with the bottom at 100 feet. It may be possible to close that gap somewhat with a parasitic reflector added to the half square. That system may only be 3.5 dB down. I think it is worth trying.
It appears that a good 80 meter antenna can be had with out extremely tall towers and lots of expense, however it may not be easy to reach the level of extremely high quads and Yagis!
I recently did a program on the Half Square at the Williamsburg Area Amateur Radio Club and also for the Central Virginia Contest Club. Click on one of the following links for the Power point presentations.
Beverages at N4DJ
N4DJ BOG Beverage on ground
(This page was last updated January 26, 2014 with the addition of a section titled: The N4DJ NorthEast BOG )
My experience with a 300 plus foot conventional beverage in 2003/2004 was not very good. One possible issue was that I lived on a salt marsh with very good ground. In fact at least once a year, sometimes more, the salt water covered the ground under the beverage. I am not convinced that was the complete issue. Second, I wound the transformer per the UN-UN design in the 1988 edition of ON4UN Low Band DXing (Chapter II, page 122). I suspect that may also have been part of the problem. I do know that I wound at least two of those transformers and used them at my waterfront QTH without any real success. I also used one of them in 2011 here at my New Kent QTH with poor results. Same results, same transformer, different location. I now think using a not so good transformer over excellent ground compounded the problem.
This year, I wound a new transformer using the FT-140-43 core. One of several I had bought in 2003. Results were like night and day! The new transformer used two windings, one on each side of the toroid. I used 11 turns on the primary and 20 turns on the secondary. I was shooting for an impedance ratio of about 3.3, thinking I needed to match a BOG impedance in the ballpark of 150 to 200 to my 50-ohm cable. (it turned out that this impedance estimate or guess was low)
The results in the CQ WW CW contest were good. It was all I used receiving on 160 meters and 90 percent of the time on 80 meters. I did not use it as much on 40 meters. I spent a lot of time, especially on 160 and 80 meters, comparing it to my transmitting antennas. The signal was almost always just as readable on the BOG and with less noise. Although I only worked 12 countries on 160 and 44 countries on 80, what I did work I heard really well. During the ARRL 160 meter contest, it was the main receiving antenna throughout the entire contest. I was amazed at how strong the European signals were on just a wire on the ground! Since the BOG was still un-terminated, I was able to use it for just about all my almost 800 plus QSOs. I could hear to the West, maybe even better than to the North East.
I wound two new transformers with the BN-73-202 cores. Both of them were 4:1 impedance transformers. Since my antenna is a BOG, I expected the input impedance to be low. I was not sure low at the present time. I wound the transformers to match 50 ohms to 200 since 200 ohms seems to be the estimated BOG impedance that keeps popping up.
Summary of test results using my old MFJ 259B:
Load = 100 ohms Expected SWR 2 measured SWR = 2
Reconfiguring of the un-terminated BOG to be a terminated N/E BOG
Measurements at the feed point of the NE Beverage December 22, 2012:
From 1740 to 1996 KHz the SWR was flat at 1.9:1. At 1997 it came up to 2.0, rose to a maximum of 2.6 at 2460 then dropped to a minimum of 2 at 3298. It again peaked to 2.3 at 3963 with another minimum at 5140, this time the minimum was 1.6.
Length of coax to the NE BOG:
December 23, 2012. I am easilly working European stations on 160 listening on the BOG that would be very hard copy on the transmitting antennas. One of them, YL2GB on SSB had me listen for his friends, some of which were no copy on the inverted L/bent half square transmit antenna.
In the next week or two, I plan to add another BOG with a feed point about 100 feet from the shack, and run it in a Westerly direction. Aside from helping hear the west coast and the Pacific, it will give me a way to check the front to back of the BOG without actually rotating it around. That would take too long. Reminds me of rotating my full size 80 meter half square. When I put it up it was on JA. Worked great to JA on 80, but before the next contest I decided I needed it on Europe. Took me four hours to rotate it. It's going to stay on Europe for more than one reason! I do not plan on rotating any beverages.
From reading what I can find about BOGs, it may be that I accidently hit on a good length due to the velocity factor of the antenna being on the ground. I can get up as much as 500 feet to Japan, just will take close to 500 feet of coax to feed it. Easier to do and with less coax will be one running SW or West. In fact one about 400 ft long running to KH6 should be fairly easy. The front lobe seems to be pretty broad, so I may only need one westerly BOG.
I will get as much done before the CQ 160 contest in January as possible.
January 2, 2013
Today I put up..I mean put down another BOG. This one was run to the West, approximately 280 degrees. The length is about 480 feet. For today it is unterminated. The feed point is not as far from the shack as I would like, but I ran out of coax and drove the ground rod at that point. I expect that this one will be mostly for test purposes. Time will tell. It is parallel to the property line. I expect I will run a permanent Beverage closer to the line and starting a bit farther from the house. Not knowing the velocity factor of this BOG, I am not sure if I exceeded the maximum effective length for signal strength or not. The BOG is fed with a 4:1 impedance transformer that I wound on a binocular core (BN-73-202).
This will now give me two BOGs that I can compare and get some idea of actual directivity. Most of my operating is with an Elecraft K3, so the S-meter readings are from "bars" being lit up on the display. Readings made with the R4C analog meter will be noted as taken with the R4C or in some cases the OMNI VI which also has an alalog meter.
This afternoon, I tuned in a VDOT station in Richmond on 1620KHz. The station was 3 S-units stronger on the new BOG than on the NE BOG. That is a good sign.
I did notice that the daytime background noise on 160 and 80 meters was stronger on the new BOG. I will call this the West BOG or W BOG from here on. Actually untill I terminate it, it is really a East/West BOG.
Also this afternoon, A station on 1690 was S8 on the NE BOG but dropped in the noise with the new West BOG.
Sunset at 5:01 local time.
At 1015Z or 5:15 local time, getting dark, a two stations can be heard on 1650 with the W BOG, when switching to the NE BOG, a different station dominates in French! I can only assume from Canada.I can copy a english sportscaster talking on the West BOG and a strong French speaking station on the NE BOG. Definate directivity!
5:31PM EST (1031Z) W1AW in 1802 KHz Strength on the NE BOG is exactly S-9. On the West BOG signal drops to S-5. same as the NE BOGSwitching at this time shows consistant 4 S-unit difference in favor of the NE BOG. The NE BOG is pointed almost directly at W1AW.On my transmitting antenna (Inverted L array) strength is almost 20dB over S-9. Strength on the Bent Half Square alone is the same as the NE BOG!
5:47 PM EST HK1R weak but about 2 S-units better on West BOG. Not moving meter on NE BOG. DK1NO calling him is best on NE BOG.
Station in Illinois was 4 S-units better on West BOG. West Virginia was 3 S-units better on West BOG. Station in Chappel Hill, NC was 3 S-units better on West BOG.
All signals up the East coast are at least 3 S-units stronger on the NE BOG than the West BOG.
MD0CCE could be copied on the NE BOG in the clear, on the transmitting antenna in the noise and not at all on the West BOG. This is good!
At 7:30 PM EST WWV in Ft. Collins, Co. was copied at S-5 on the West BOG and bearly detectable on the NE BOG. Audio was Q5 on the West BOG, no copy at all on the NE BOG.
So far it looks like things are working as expected.
January 4, 2013
I terminated the West BOG with about 330 ohms of resistance. The SWR is now almost prefrctly flat across the 160 meter band. 2:1 at 1800 KHZ to 1850, then 1.9:1 from there to 1.96. Again 2:1 up to 2300 KHz.
At 5:00 PM EST the Richmond VDOT station on 1620 was still 3 S-units stronger on the West BOG than the NE BOG. A station on 1650 was a solid 10dB over S-9 on the NE BOG and dropped to S-7 on the West BOG.
On 1660 I hear a sports station on the West BOG and switching to the NE BOG I hear WWRU a Korean language station in Jersey City, N.J.
At 5:30 PM EST W1AW is 4 S-Units stronger on the NE BOG. S-9 on the NE BOG and S-5 on the West BOG. On 40 meters W1AW is only 5 dB stronger on the NE BOG. On 80 there is also about 5dB difference.
Background noise is still stronger on the West BOG by about 1 to 2 S-units on 160, and 1 S-unit on 80. I can not detectany difference in the background noise on 40 meters, it appears to be the same on both the West BOG and the NE BOG.
Even with the increased noise on the West BOG, I can copy some stations on it that I can not hear at all on the NE BOG.
One station in Stafford, Va was identical on both antennas. According to the map, his bearing from me was 337 degrees. According to the EZNEC plots I made of the West BOG and the EAST BOG the bearing where they should be the same is about 344 degrees!
Below is an EZNEC plot of my European (NE) BOG and my West BOG. The elevation angle is 20 degrees for both plots. The green dot is at 244 degrees. I have the plots rotated so they point in the correct directions, North being straight up.
In the above plot, the West BOG is 480 feet long and the NE BOG is 220 feet long. In addition to the station at 337 degrees being the same on both antennas, yesterday I was listening to two stations, one at 339 degrees and one at 356 degrees. The one at 339 degrees was at least 1S-unit stronger on the West BOG, while the one at 356 degrees was about 2 S-units better on the NE BOG. This seems to be pretty close considering an S-unit is about 5 dB and I am using a K3 with "bars" for an S-meter!
Below are two tables where I calculated the length for maximum signal for a 160 Meter BOG and a 40 Meter BOG. The 40 meter max length is reached with quite short lengths. So far I have not tested the BOG much on 40 Meters. The West BOG does still seem to give the strongest signals from stations to the West. I am not sure how fast the signal will actually drop off past the maximum signal length. Maybe further testing on 40 meters will give an indication.
Table I (for 160 meters)
Table II (for 40 meters)
January 6, 2013
I changed the 4:1 impedance transformer on the West BOG to a 7.56: 1 impedance ratio. After testing several different ratios I zeroed in on 7.56 to give me the best match.
The SWR measured at the Receiver is 1.1 to 1. SWR is flat at 1.1 from 1.76 to 1.95. In fact the SWR is 1.2 or less for the range of frequencies 1.76 to 7.0 MHz. The length of coax to the receiver is close to 50 feet.
This is a table of SWR readings I made at the 50 ohm port on the transformer enclosure for my 480 foot West BOG. I wound six transformers and measured the SWR with each one of them in the circuit. The termination resistor in all cases was 330 ohms. These readings were taken with the transformer connected with clip leads. The SWR with the 7.56 transformer installed permanently dropped to 1.1 to 1.
These are my Beverage boxes to house the impedance transformer and the termination resistor.
The transformer is wound on a BN-73-202 binocular core. The box is a little large for such a small transformer!
Looking along my West BOG. Light orange wire can just be seen on the ground.
This is the feedpoint of my NE Beverage.
Measuring to see how far I can extend the NE BOG. I can go from 220 ft to about 450 ft.
Layout of my two existing Beverages or BOGs.
Click to see a video where I switch from the NE BOG to the West BOG: Listen to the Beverage
January 9, 2013
The BOGs are impressing me.
Things I need to do.
I want to change out the impedance transformer on the NE BOG. It is a 4:1 impedance transformer. My first guess was the impedance of the short BOG would be in the 200 range. Since the SWR turned out to be 2:1, (just like the West BOG with a 4:1 transformer), I plan to try a 7.56:1 transformer and see how close I come. In my experience, having a 1:1 SWR on the BOG instead of a 2:1 does not really affect the performance. Note that my comments on SWR apply to using single antennas and not connecting them in a phased array where SWR on the line would be an issue.
Since the 220 foot BOG is entirely in the woods, I could extend it another 200 feet or so across the back yard during the winter. I would like to drive another ground rod and put a terminating resistor at that point so I could simply disconnect the antenna from the resistor at the 220 foot point and run a piece of wire across the yard and terminate it at maybe 440 feet. When it is time to mow the lawn, I can roll it up and put it away untill next fall. Thus keeping the 220 foot BOG year round.
Looking for more coax. I need to run a South Beverage. This week I had to listen to VP2M and KP4 on the transmitting antenna. Now knowing what the BOG can do, I am anxious to have one pointed South!
When I do get all that coax, I then need to run one toward JA and KL7!
Not sure much can I get done before the CQ 160 contest.
Next years project will probably be to raise the BOGs to 7 or 8 feet and see what happens. From my EZNEC modeling things may get even better!
January 10, 2013
I ran a wire through the woods to the South in case I am able to get enough coax to connect it before the CQ160 meter contest.
January 12, 2013
I just got a 1000 foot roll of RG-6 quad shield coax and some waterproof connectors. Looks like this week I may get a south Beverage. With a 1000 foot roll, I may be able to make the South Beverage at least 300 feet maybe even 400. If I have enough left from the 1000 foot roll I could even get a JA/KL7 Beverage up. I plan to put these next two Beverages at about 7 to 8 feet high.
January 15, 2013
It's been raining the past few days. I have wire, coax, connectors, insulators, transformer and a 450 ohm terimination resistor ready for the rain to stop. In the meantime, I counted my 160 DX QSL cards. Adding the LOTW confirmations and the QSL cards gives me 97 countries confirmed on 160. It looks like, after 50 years on 160, I will soon make my 160 Meter DXCC! I have 122 worked.
Today using the MFJ 259B at the receiver, 50 foot of coax to the feedpoint of the West 480 foot BOG, I am measuring a perfect 1:1 SWR from as low as the MFJ will go (1.74 MHZ) up to 2.15 MHz. The SWR is 1.1to 1 across the entire 80 meter band. This indicates the impedance at the primary of the 7.56:1 transformer is 50 ohms. With an impedance step up ratio of 7.56 the impedance of the BOG should be 378 ohms. This after a good two days of rain.
As a check on the MFJ, I connected a precision 1% 51.1 ohm resistor directly across the connector and measured 51 ohms from 1.74 to 15 MHz.
Measurements made in December on the NE BOG, 200 feet long with a 4:1 impedance transformer (I have not taken the time to change it out with the 7.56 transformer yet) show the SWR to be 1.6 to 1 across the 160 meter band and 1.3 to 1 across the 80 meter band at the receiver (coax length about 500 feet) At the antenna the SWR was measured to be 1.9 to 1. As a result the impedance the antenna itself should be 50 X 1.9 = 95 and then 95 X 4 = 380. This number is very close to the 378 I came up with for the West BOG.
January 20, 2013
I connected the South Beverage today. First as an unterminated beverage to test it. Comparing to my West (W) and North Easy (NE) Beverages (actaully BOGs), I found that I could hear the Washington DC station on 1500 KHz better on the bi directional South Beverage. This was expected. So far so good. Checking on the VDOT highway station in Richmond on 1620 (due West) I found the signal strength was the same on the S Beverage as on the NW BOG, about 15 dB down from the West BOG. Listening to 1490 in Hampton, I was now able to copy that station on the South Beverage and not on the W or NE BOGs.
I then went out and connected the terminating resistor (470 ohms). I immediately noticed the station on 1500 in Washington DC went down on the South Beverage to now be the same strength as on the W and NE antennas. I noticed 10 dB decrase, but as the signals were getting stronger as the sun goes down, I think the front to back may be much more than 10 dB. It will be interesting to listen on 160 tonight.
At 2247 UTC (5:47 Local) I worked HK1R on 160 Meters. He was 3 S-units stronger on the South Beverage than on the NE Beverage! My EZNEC plots indicate there should be a 15 dB difference between the NE and S beverages in that direction. It looks like everything is working as it should.
Below is the layout of my three Beverages as of January 20, 2013.
Below is the EZNEC plot of my three Beverages. Note that HK1R is almost due South at 175 degrees and the difference between the NE Beverage (Red) and South Beverage (Blue) is 15 dB.
January 28, 2013
The 2013 CQ 160 contest is over. The beverages made a big difference. Switching to the right beverage meant the difference in making a contact or not. I owe most of my European QSOs to the NE Beverage. There were many stations that called me that I would never have heard on the transmitting antenna. They only could be copied on the NE BOG.
Several times as I switched form NE to W or S I heard stations calling me only on one of the Beverages. If a station was weak, I would switch the beverages and it would make a 2 or 3 S unit difference on my K3 meter.
Next I will change the coax to my NE Beverage from RG 8X /LMR 400 to RG-6. I can use the 500 foot of 50 ohm cable for something else. The RG-6 is cheaper. I also need to move the feed point of the West BOG out of the back yard lawn area. I will also feed it with RG-6 instead of RG-8 type of coax. The RG-8 is old, so I may even improve things with the new RG-6.
January 30, 2013
The subject of connectors has come up several times in the past couple months so I thought I would address it here.
To save time, if you do not read any further, the bottom line, if you want a long lasting connection, is use the best connector you can get with possibly an o ring or something to seal the threads, dielectric grease/filler, like STUFF (not conductive grease), torque to about 20 to 30 in-lb, wrap with self-fusing tape.
Slightly more detail:
My recommendation is to beware of any "waterproof" claims when you buy connectors. I think of waterproof claims like I do dB gain of an antenna. What is the reference?
I always try to never let the "night air" get on my connectors with out first taping them.
I found this list of products that can be used as a guide.
Frank, W3LPL, provided this link for STUFF: Link to Stuff
February 4, 2013
Thinking about the impedance of the West BOG. It is 480 feet long and I am feeding it with 50 Ohm coax. I plan to switch over to 75 ohm coax. I determined that the best impedance transformer was the 7.56 :1 ratio with 50 ohm coax.
Since I recorded all my SWR readings with seven different impedance ratios and plotted them on a graph, I should be able to determine (or guess pretty close) the actual impedance looking into the BOG wire.
Looking at the graph it would appear that since I got the same SWR with the 7.56 and the 9 to 1 ratio transformers, the ideal ratio might be in between these two values. If that is indeed the case then the ratio would be maybe 8.25:1.
These readings were all taken at the feed point of the BOG before the 7.56 transformer was installed permantly. Based on this information the input impedance of my 480 foot BOG would be approximately 8.25 times 50 or 412 ohms.
So to match 412 ohms to 75 I would need a transformer with an impedance ratio of 5.49. That would require a turns ratio of 2.34.
So how close do I need to be? I was using a ratio of 7.56 with 50 ohms, that equates to 50 X 7.56 = 378 and I got a good match. With 75 ohm cable a ratio of 5 would give me about the same thing 75 X 5 = 375.
It looks like ratios of 5 and 5.44 will be easy to get.
Here is a chart showing which ratios are easy to obtain (note that primarys using 2 or 3 turns is probably best with binocular cores):
My plan is to first measure the SWR at the feedpoint and record that, change the coax, measure the SWR with the existing 7.56 transformer and then change the transformer to probably the one with a 5.06 ratio.
Once I have changed the coax over to 75 ohms, I will have to use a 75 to 50 ohm transformer at the MFJ 259B to be sure of correct readings (or at least the most accurate readings my instrumentation is capable of giving me)
I think I have the answer to my original question which was "What is the impedance of a BOG at my location?"
The answer is pretty close to 400 ohms for a 480 foot BOG terminated with 330 ohms.
February 5, 2013
Just finished replacing the 50 ohm coax to the NE BOG with 400 foot of RG-6. The 50 ohm coax will now go back to the 15 meter wire Yagi .
A quick check of the usual daytime broadcast stations indicated the antenna is still working. It's 3PM local time and I hear a station broadcasting sports in English a solid S7 on the west BOG. Switching to NE, I only hear the station in Jersey City broadcasting in Korean around the S3 level.
Measurements on NE BOG:
Using my MFJ 259B with a 50 to 75 ohm transformer (4 turns to 5 wound on a binocular core, actual ratio 1.56:1 so its really a 50 to 78 transformer) connected to the RG-6 feeding my NE BOG I get an SWR of 1.0 from 1.74 MHz to 2 MHz where it jumps up to 1.1 all the way to 7 MHz. Then the SWR is 1.2 from there up to 9 MHz. With the instrumentation used I could not get any closer!
To summarize the NE BOG: 220 feet long on the ground. Fed with 400 feet of RG-6 Quad sheieded cable. Terminated with 160 ohms. 5 foot copper clad steel ground rod at both ends. Transformer is 4:1 impedance ratio. Four turn primary and eight turn secondary #22 wire on a BN-73-202 binocular core. It looks like the input impedance of this BOG is very close if not exactly 300 ohms.
February 19, 2013
The BOGs and Beverage worked really well in the ARRL CW DX contest this past weekend. I was able to work 114 QSOs in 48 countries on 160 meters. I spent a total of about 7 hours on 160, almost all was on Saturday night. The Beverages also worked very good on 80 meters to the tune of 53 countries. All 160 and 80 meter receiving was all done on the Beverages.
Heard real well in the CQ 160 Phone contest. Many times a W1, 2 or 3 would call and I had trouble getting their call listening on the NE Beverage. Turns out they were in Florida and switching to the south Beverage brought them up to Q5. Worked 29 DX stations on SSB in 19 countries. I worked 530 QSOs overall in the contest. All of my receiving was done with the three Beverages.
February 25, 2013
Measured the velocity factor in the area of my North East BOG today, as best I could. I did not use the best method, but I think it got me very close. I took a 40 meter dipole that was 65 feet 4 inches long. I will use the number 65.33 in my calculations. This dipole is normally resonant somewhere in the 40 meter bandwhen up in the air. By putting it on the groundjust like my Beverage on the Ground (BOG )the resonant frequency will go down. Note: do not try and tune a dipole on the ground, because when you raise it to a normal height it will be resonant at a much higher frequency.
By measuring the resonant frequency of the dipole on the ground with my MFJ 259B analyzer I read about 5.7 MHz. I moved the dipole around and took several measurements. In the woods area where I have my NE BOG, I got readings all very close to 5.7 MHz.
To calculate or estimate the velocity factor I determined the free space wavelength of a half wavelength at 5.6 MHz. 491.8 / 5.69 = 86.43 feet
Since the length of the wire was 65.33 feet, the ratio of 65.33 to 86.43 is the velocity factor. 65.33/86.43=.756 So the velocity factor is .756 or 75.6%.
It would have been good to have the dipole a full 220 feet so I would only need to take one measurement. This would have meant the antenna analyzer would have to measure a reasonant frequency in the neighborhood of 1.2 MHz. My MFJ will not read that low. The best that can be done with the MFJ is to have a dipole about 204 feet long. In that case with a 75% velocity factor you would measure a resonant frequency of about 1.808 MHz.
The calculation than would be something like 491.8/1.808= 272 then 204/272=.75
I think this method will give you a good idea of the velocity factor you have at your specific location. One good thing is the Beverage lengths are not all that critical.
Here is a link to a video of this process at N4DJ: Measuring Velocity Factor
As additional information I am adding a chart of the measurments I made on my 40 meter dipole at various other locations and will update the chart as I take more measurements.
I wish to note that knowing the velocity factor makes Table I (for 160 meters) above more useful. Do not take the maximum lengths in that table too literal. For example with a velocity factor of 75 percent, the table shows different maximum lengths that relate to each arrival angle. Going longer that length is not very noticable. Going longer will tend to reduce interference or signals from higher angles. Going shorter will tend to raise the angle of maximum signal. The pattern is somewhat broad and forgiving. It is best to model an antenna to see the effect of extreme deviations from lengths given in Table I.
I will add some elevation plots of various length BOGs soon.
The N4DJ NorthEast BOG
I thought I would condense the information on my NorthEast BOG. This is what works for me at my particular location. I think it would get anyone in "the ballpark". From my experience, with a single wire beverage or BOG being " in the ballpark" will work quite nicely. If for some reason you are not "in the ball park" the Beverage seems to just not work at all. Single wire Beverages seem to be very forgiving if you vary the termination resistance and even the transformer ratio. The exact termination value will affect the front to back and the angle of the null off the back and sides. I have some EZNEC plots of my BOG with different termination resistances. The model indicates that values such as 450 and 470 are "out of the ball park" for BOGs. Values from 160 to 300 are "in the ball park". From the EZNEC plot below, the 161 ohm and 200 ohm terminations really pull the back of the curve in tight. The 100 ohm termination is slightly better at the higher angles, but not at low angles. Remember we are looking at directivity and not gain off the front as would be normal with most antennas. The 450 and 470 ohm termination curves shows poor front to back. Naturally if your noise was arriving at only the 55 degree angle, you would want a termination value closer to 100 ohms. I chose 161 ohms for my North East BOG. Sometimes its better to be lucky than good. I actually picked the value before I did the model. EZNEC just confirmed I had a good value. Probably anything from 150 to 250 would give very similar results.
The North East BOG is simply an insulated wire strung on the ground as straight as I could roll it out. Slight deviations are not a problem, neither are slight up and down or rolling hills. One way to look at it is to measure the straight line distabce from the two end points. The "effective" length is that distance. Even if the wire makes a "S" shape in between. It is not the length of the wire along the curve that matters, but the length of the path that the incoming signal takes going from one end to another.
The termination end of the BOG is simply connected to a ground rod through the resistor. Short leads, non inductive resistor. That means not a wire wound resistor! We do not want any inductance in series with the BOG. That would complicate the EZNEC model too much for me.
The feed point needs about a 4:1 impedance transformer. I am using 75 ohm RG-6 coax. 75 times 4 gives me 300 ohms. The actual turns ratio is 2:1. I am presently using BN-73-202 cores. These are binocular cores. I also have had good luck with standard FT-140-43 toroidal cores. I think the most important thing is to not ground the coax near the antenna. The antenna wire is grounded through the high impedance side of the transformer to a ground rod. The low impedance side of the transformer is connected to the coax. Do not ground the shield to the ground rod. There should not be any direct connection between the primary and secondary. I once tried using an autotransformer circuit and it seemed to put me "out of the ballpark". Those beverages were useless. I can not be certain but I suspect the transformer.
When winding the transformer, I do not worry about exact ratios. The primary can only be 2, 3 or 4 turns at most. A 4 turn primary is a bit much. (Note: I am not sure why I wound a 7.56:1 transformer. That was not necessary and it was too hard to fit the wires in the core! ) With a BOG the impedance should usually be between 300 and 400. So with 50 ohm coax you need a ratio of 6 or 8. With 75 ohm cable you need a ratio of 4 or 5. these are just ball park figures. In practice you only have certain ratios you can wind. Considering we are looking at only the range of ratios from 4 to 8, a binocular core with a two turn primary will only yield ratios 4, 6.25 and 9. Add to this a possible three turn primary and your choices increase slightly to : 4, 5.44, 6.25, 7.11, and 9. I think 4 and 5.44 will work fine for 75 ohm cable, 7.11 and 9 work for 50 ohm cable, with 6.25 being fine for either.
I changed my cable from 50 to 75 ohms this year on my west BOG. I have not yet changed out the transformer. My west BOG has been working just as good as it did last year, consequently there is no reason to replace the 7.65:1 transformer with a lower ratio. It does not seem to be broke, so I am not going to fix it!
This is an EZNEC plot of a 200 foot North East BOG. This plot shows signals off the back and sides are down more than 10 dB at a 20 degree elevation angle. Depending on the exact termination resistance the rejection off the back and sides can be 10, 15 or more dB. It can be hard, if not impossible to figure the exact termination resistance. The ground resistance, whatever that may be, is in series with the physical resistor. So if the resistor you pick is 160 ohms and the ground resistance happens to 30, the total is 190 ohms. I always assume the actual total resistance is going to end up a bit higher than the value of the terminating resistor. So even though I used 161 ohms as a termination in EZNEC, we can be confident that the real value is a little higher. With all the unknowns involved it is not necessary to try too hard to calculate exact values. That's why I say just get in the ball park! From the performance of my BOG, I think I must be pretty close to the plot using the 161 or 200 ohm termination, probably right between the two curves. I also have plotted values for all three of my Beverages and have very good correlation between what EZNEC predicts and what I can see and hear on my receiver. As an example, using EZNEC plots, I can see that in one direction the signal from the West BOG and the NE BOG should be the same. That is the direction where the curves cross. When switching the BOGs on a broadcast station in that direction there is usually no difference in signal strength. Doing many such tests as this I have developed a high confidence in the EZNEC plots. Obviously results vary from day to day and hour to hour depending on the height of the ionosphere, etc. making the exact difference in strength vary at any given time.
As I write this I just finished the 2014 CQ 160 CW contest. I made 707 QSOs. All receiving was done on either a BOG ot Beverage.
Summary of New Kent BOG/Beverage Antennas
I ended up with two BOGs and one conventional Beverage.
The North East BOG was 220 feet long on the ground. Fed with 400 feet of RG-6 Quad sheieded cable. Terminated with 160 ohms. 5 foot copper clad steel ground rod at both ends. Transformer was 4:1 impedance ratio. Four turn primary and eight turn secondary #22 wire on a BN-73-202 binocular core. It looks like the input impedance of this BOG was very close if not exactly 300 ohms.
The West BOG was 480 foot long. Fed with RG-6 coax. Terminated with 330 ohms. 5 foot copper clad steel rods at each end. Transformer was 7.56:1 impedance ratio. BN-73-202 binocular core.
The South beverage was between 220 and 300 foot long and 6 foot high. Terminated with 470 ohms.Transformer was 9:1 impedance ratio. BN-73-202 core.
December 4, 2014
Put down my first BOG at my new Williamsburg QTH. The transmitting antenna is my 160 meter inverted L.
The BOG runs North East and is about 100 ft long. I expect it to be as good on 80 meters as my 220 foot NE BOG at my new Kent QTH was on 160. The 160 meter performance on a 100 ft BOG is not expected to be as good as the 200 foot length, but I plan to give it a try. So far it does receive quite well on 160, 80 and 40 meters. At the present time I can only compare it to my inverted L. On the broadcast band, where it is extremely short, I was able to copy a station to the NorthEast better on the BOG than on the Inverted L. I could hear two stations on the inverted L, neither clear, and switching to the 100 ft NE BOG I could clearly copy the station to the NE. That is very encouraging. EZNEC plots show there is a small front to back on 160. Plots for 80 and 40 meters show a very good pattern. I think it is possible that this 100 ft BOG will actually be better on 40 meters than the 220 foot one at New Kent.
This weekend is the ARRL 160 contest and I hope that the NE BOG will be helpful in copying stations to the NE. I have it connected to a switch where I can connect it to either the AUX input on my K3 that goes to the SUB receiver or the Receive antenna input where it can be used on the main receiver. The normal mode for me is to connect it to the AUX input (sub receiver) and runboth receivers in diversity mode. This way I have the main receiver with its antenna (inverted L at the present time) in my left ear and the sub receiver with its antenna (NE BOG) in my right ear. I hope to eventually have another BOG or two, in that case I would have the NE BOG always on the Sub Receiver and the main receiver would be switchable among all the other antennas. Last year I had three receiving antennas, NE BOG, West BOG and South Beverage. All low band receiving in contests was done with these antennas. The NE bog on the sub receiver and the West and South antennas were connected to the K3 main receiver with a two position switch.
Due to time constraints, I used the same terminating resistor and transformer that I used on my 480 foot west BOG last year. Termination is 330 ohms and the transformer impedance ratio is 7.56:1. I have every intention of changing the terminating resistor to about 150 and the transformer to 4:1 after I use this antenna a while.
The short 100 ft BOG receives quite well on 160 through 40 meters. I need another BOG in a different direction to be able to do a good evaluation. However my three receiving antennas (two BOGs and one Beverage) at my last location performed exactly like the EZNEC modeling predicted. So I will start with modeling the antennas.
First off I know that my present NE BOG at 100 feet is less than half of my 220 foot NE BOG. Logically I would expect the 80 meter performance of the short BOG to be similar what the longer one was on 160 meters and for the new short one to be on 40 like the longer one was on 80. I also know from my calculations that 220 was on the long side for 40 meters. My table II (for 40 meters) above indicated 105 feet was the length for a zero angle and 89 was the number for a 20 degree wave angle. I am expecting my 100 ft BOG to be really good on 40 Meters and just as good on 80 as I experienced my 220 ft BOG on 80. Time will tell.
40 Meter BOG
Modeling the 100 foot BOG with the 330 ohm termination on 40 Meters was a bit of a surprise. I knew that a 100 foot BOG would be a great length on 40 meters. What I did not know was I accidentally used a very good termination resistance. The 330 ohm termination just worked out to be almost exactly what I would want! Although the null is deaper with a higher termination (900 ohms in the plot) the 330 termination has a better front to back. Lower terminations arejust not as good.
Here is the elevation plot:
Here is the azimuth plot (note the 330 ohm termination looks to be the best) :
Both plots look quite good.
The 220 foot BOG worked really good on 40 at my last QTH, so here is a 40 meter comparison of the old 220 ft BOG and the new 100 ft BOG:
It appears that the 220 foot BOG has more gain at a lower angle, but gain on a receiving antenna is not that big of a deal. Over all, the 100 foot BOG may not look quite as good, but still a very good pattern. It does have a null off the back that is better than the 200 ft BOG.
N4DJ Station 2011 OMNI VI (Mod 3) and Drake L7 Wire antennas with 3 beverages
1990s Station Drake C-Line and Drake L7 is the main rig. Full size 4 element 20 meter monobander on 70 foot Rohn 45
6191000 Last modified: 2015-07-16 00:22:59, 92986 bytes
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