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Hi thanks for visiting my QRZ page. My QTH is the town of Flat Rock in  the Mountains of Western North Carolina.  I moved here several years ago from Connecticut, hence the "1" in the callsign while living in "4" land.  You can read my ham radio ramblings at:

http://www.hamsignal.com


 

At present, my interests are in 630M/2200M experimentation and digital QRP communications. I live in an antenna restricted HOA, so my antenna farm is hidden in the wooded portion of my property.  The farm consists of 5 vertical delta loops cut to resonance on the 80, 40, 20, 17, and 15M bands, one experimental magnetic loop, a 160M inverted L,  and a 6 parallel element ( 70' vertical X 200 ft horizontal) Low Band Vertical/Horizontal antenna for use on 630M/2200M and 160M-6M through a remote relay system and several VHF/UHF antennas.  

 

Components of the 630M/2200M antenna. The large coil provides course tuning of the antenna with inductance capability of 1,200 uH.   The small coil in the control box allows fine tuning of  0-100 uH.  The impedance transformer allows selection of 17 taps to convert impedance to 50 ohms on both 630M and 2200M.  10 positions are tapped on the large coil and transformer (not shown) and can be selected from the shack via a remote relaty system   Unlike most stations operating on low bands, I rarely need to go outside to retune my antenna.


The box to the right of the large coil at the top is the relay that switches the 630M/2200M coil out of the antenna while switching in a remote LDG tuner for use of the antenna on 160M-6M.  Note the windings on the inductor coil are seperated by approximately 1 wire diameter for each turn.  I found that this was necessary to reduce stray capacitance and thus the need for inductance to resonate the antenna. When I replaced my variometer with this coil, WSPR contacts went from a daily of 6-12 'spots' up to 70-80 'spots' per night with several European contacts.  On 2200M, I consistently contac stations betwen 1500-2000 km away with an EIRP of 0.4 watts.  My furthest contact to date on 2200M is N6LF at 3200 km.

 

Relays installed to allow tap selection on the inductor and transformer from within the shack.

 

 

For 630M transmissions, I use an ICOM 7200 paired to a Monitor Solutions transverter.  On 2200M, I use a QRP-Labs Ultimate 3S with a 2200M low pass filter.  The signal is attenuated and trnsformed to 200 ohms for use by a Hafler P1500 audio amplifier which generates 153 watts to produce 0.4 watts EIRP at the antenna.

 

Original matching variometer.. It worked, but the tight coil winding was limiting efficiency of the total system, presumably through generation of stray capacitance to ground.  The most expensive part of the system was the bushes to hide the bucket from neighbors' eyes.  The variometer would tune 630M, but not 2200M.

 

 

​After swapping out the variometer for the single loosely wound matching coil, I am being heard by almost all 630M stations east of the Missippi at 5 watts EIRP.

A 3 Band - 2 Trap Inverted L

​The 3 band - 2 trap inverted L can be found on several websites.  They all rely upon traps constructed of coax which tends to be quite lossy. I replaced those traps with 14 ga stranded wire in parallel with 3KV capacitors which is more than sufficient for operation at 100-200 watts. Both were wrapped around 2" PVC pipe.  The 40M trap contains 10 turns of wire and 110 pf of capacitance while the 80M trap contains 14 turns of wire and 220pf of capacitance.  Using a dip meter, each trap was then modified with partial coil turns to resonate in the digital portion of each band of operation.  After this was done, the capacitors and connecting wire were covered in silicon glue on the inside of the traps to provide structural support and protection from the weather.

Starting dimensions for the antenna were as follows:

1st vertical section = 32 ft and connected to the 40M trap.
​2nd vertical section = 29 ft and connected to the 80M trap
​3rd horizontal section = 41 feet and terminated with an insulator

​As this antenna is going to be impacted by the quality of it's radial system, I recommend a temporary placement where the antenna can be quickly raised and lowered because trimming of each section will be necessary to obtain an optimal SWR on each band.  For those who have never done this, trim the 40M section (bottom) to resonance first, then trim the 80M section (middle).  Go back and check/trim the 40M and 80M sections a second time as they will interact somewhat.  Finally, trim the 160M section and go back to the 80M section, if needed, and trim again.  Although in theory, each antenna element length should not greatly impact SWR on the other bands, I have not found this to be the case.  So repeated deployment, taking down, and retrimming are necessary to optimize the antenna for all three bands of operation.

​When finished, my antenna has an SWR of 1.3:1 on 40M and 160M and an SWR of 1.5:1 on 80M in the digital portions of each band.   2:1 bandwidth covers about half of the 160M band, a little less on the 80M band, and almost all of the 40M band.    Note that a reduction in gain relative to non-trapped antennas will occur, but that is to be expected in any trapped antenna.  However, the ability to operate all three bands with one antenna makes a little bit of loss in gain an acceptable tradeoff.

​In WSPR, JT65 and PSK31 testing, this antenna has proven comparable to other antennas I have deployed for 40M (vertical delta) and 160M (non-trapped inverted L). It is superior in preformance to the triple inducted delta loop for 80M (see below).

 

A Happy Accident: Combining the 3 band inverted L and a traditional 160M inverted L

​This antenna system started as a result of a desire to share the radial field between my standard 160M inverted L and the new 3 band inverted L (described above).  What I initially did was add a manual switch to the original inverted L's balun box so that I could toggle between use of my original inverted L and the 3 band inverted L.  On the first evening that I used the three bander in a rough parallel approximation to the 160M L, I noted a BIG improvement in transmission on WSPR on 40M.  This led me to modeling the two antennas when the vertical elements were placed in close parallel proximity.

 

​What I found was a dramatic improvement in gain and directionality with virtually no impact on 160M (just the opposite of what I expected).   The following charts show the parasitic currents generated when the two antennas were oriented in this manner.  Compare them to the charts (above) for the tri-bander in isolation from the 160M inverted L.

 

 

 

Gain Comparison

Band          3 band trapped          in Proximity to Inv l

40M            0.79 dBi                      6.17 dBi

80M           -2.10 dBi                        4.68 dBi

160M         -4.80 dBi                       -4.80 dBi    (retains + 0.79 dBi on original L)

By using the original, ungrounded inverted L as a parasitic reflector, dramatic improvements in gain could be generated on the 40M and 80M bands.  However, the electrical characteristics on the trapped antenna changed considerably once the second antenna was brought into play.  Impedance approximately doubled on the 40 and 80M bands from approximately 40 and 75 ohms to 75 and 135 ohms while the 160M band held constant at 65 ohms.  Because of this change, SWR on the 80M band jumped from less than 2:1 to greater than 8:1 in the modeling (actual results showed a jump to apoproximately 5:1 on 80M).

​This observation led to the conclusion that utilization of a 2:1 balun would result in a much improved SWR on the 80M portion of the tri-band L and little impact on the 40M and 160M bands due to a drop of impedance back to roughly the 1:1 balun values.  However, I did not want to lose the advantage of a near perfect 1:1 match on the original inverted L on the digital portion of 160M.  So, this led to the creation of a manual in-line switching system to swap out the 1:1 and 2:1 baluns along with selection of either the original inverted L or trapped inverted L as dictated by mode and band of communication.

Two balun - Two Antenna Switch Box

 


40M WSPR Contacts with the 2 L antenna design - 5 watts, 1 hour  operation


​160M WSPR Contacts with 2L antenna design - 5 watts - 3 hr operation

The 2 Meter HO Antenna

​This antenna started out as a design by GW7AAV which worked quite well.  However, N1HO pointed out to me that the antenna was horizontally polarized, and what I wanted was a vertical polarized portable antenna to hit a wide range of repeaters in the area surrounding my QTH as well as occasional simplex FM operations.  So, I redesigned the antenna which is basically a common 2 element delta beam with the addition of a director to further improve directivity.  So far, the HO antenna seems to be working quite well both from modeling (4NEC2) and from practical application.  At 28 feet, I can trigger a repeater that is 40 miles due south from my location.   Angle of maximum radiation is 5 deg. from horizontal with a gain of 11.4 dBi.  Resistance at the resonant frequency of 145.75 mhz is 52 ohms (no balun or matching device needed) and the SWR remains under 1.6:1 from 144-148 mhz. F/B ratio is approx 40:1. The schedule 40 pvc joints are all glued into place with the exception of the base joint for each element which allows the antenna to be disassembled or folded as seen below. Here are the specifications and some information about the antenna:

 

 

 


The antenna farm from the road in front of my QTH.  Careful placement of feedlines behind trees and connection points in branch junctions have resulted in an antenna system that is difficult to spot.  When neighbors ask me why I spend so much time in the woods, I tell them I am beautifying to support the HOA  hi hi! 

 

 

N1DAY triple loop (retired).   This design resulted from some modeling I did on loop antennas after developing the two element parallel loop (below).   The modeling showed that gain of the antenna could be greatly varied by spacing of the radiating elements and that as the elements were moved closer together, gain would continually increase before finally dropping like a rock (sort of like the Chinese stock market). It appears that when spaced closely, resistance due to proximity effect kicks in and tanks the antenna perfromance.  So, I built this loop starting on 10" center spacing of the elements, then moved them closer together in 1" increments while measuring RF intensity at 1 wavelength.  Sure enough, the real-world results mimicked the modeling, and gain peaked somewhere between 5-6" element spacing, and finally dropped to almost 0 RF activity  at 4" spacing.  I will be doing more testing in the near future to fully quantify the performance of the antenna.  For now, though, I am having fun making PSK contacts with signals on the waterfall that I can barely see when using my 'go to' 40M skywire loop.

 

Update on the N1DAY parallel conductor loop (retired).

Testing is now completed with the N1DAY loop. At 10' and 67 feet on 20M, the loop is outperforming the MFJ 1786 and a one turn loop made out of 2" copper strap. It also seems to perform as well as my 40 M skywire loop with significantly less background noise Without getting into all the math here, the loop has achieved both an increase in bandwidth and signal strength relative to a single turn loop of the same size.  In the past month, under difficult conditions, I've made numerous contacts to the West Coast, South America, and Europe with the loop.   Measured ohmic resistance is .211 ohms which is much better than I expected.  That in conjunction with the reduction in skin effect tht occurs with multiple loops is giving a very efficient antenna with an equivalent size of 1.42 X the actual area of the loop.  Gain is approximately 13 dBi on 20M.

 

Why does it work so well?   In a nutshell....

- Radiation resistance is a function of enclosed area by each loop - adding loops in parallel causes this good resistance to go way up.

- In parallel -  two resistors of equal value equals one resistor of half the value....  So in a 2 loop system, structural resistance is decreased.

- The spacing and size of the radiators results in the equivalent of a very large diameter tube.  As a result, the skin effect losses at any frequency are reduced relative to the traditional 1" tube.

- Spacing of the flat straps all but eliminates resistance due to the proximity effect.

Taken together - all of these factors equals a much more efficient magnetic loop antenna.

 

 

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My one turn mag loop with an 11' X 2" X .033" flat strap radiator (retired).  This one works from 40-15M and really performs well with a tunable SWR of 1.1:1 on 20m.  Great little antenna for digital operation. 

 

 

 

CQ CQ.....  Radio Dog 1 Barking CQ and listening

 

 
An unexpected visitor while transmitting from my mobile station.

 


N1DAY Mobile QRP

 

 

 

 

Bear Ridge Mountain from my new QTH in NC

Sentell Knob - the view from the deck at my QTH

 

Corn Meal Shoals - just a short drive from my QTH

 

 

 

 

Kipper Snax - Last known survivor of the chipmonk wars.  RIP Kipper - you were one of a kind.

 

 

 



 

 

 

 

8596642 Last modified: 2018-01-22 00:43:35, 19942 bytes

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