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... my inventions are to save humanity not to destroy it ... Guglielmo Marconi

 

First of all many thanks for visiting my page

 

I am on air since 1978-79 (I was about of 13 years old on 11m band) driven by love for adventure, travels (unable to experience them in practice at that time) and incredible curiosity for the world.

Later on this passion developped driving me to become Dr in Electronic Engineering in Communication and Broadcasting. I always kept my radios while my job moved me across many places, cultures and experiences abroad (and keep ongoing this way). Radio was left apart for a while until switching it on again the passion came back or (may be) better to say never left in reality.

Today -as always- I have more projects in mind than time to turn them in to reality.

Due to my job I am living and working abroad on stable basis, therefore I am able to activate my station just during limited periods of holiday every five months as an average.

This is the reason why every time I am back to my home land I like to put in practice new projects, execute new upgrades or test new antennas what I had time to elaborate in detail from far distance.

 

My personal rules to have fun

1) Excellent installation (as much as environmental constraints allow us to do) and perfect tuning of antennas, I am active in HF in this moment

2) Power: 100 to 200 W max, if I need more It mean I need to work on my set up and/or installation

3) Listen carefully and place the call at the "right time" with 100-150 Watts; proper timing call is worth more than 1 KW

4) High power is polluting the world, wrong behaviour even more; code of conduct first

5) My shack: simple, high tech, minimalist and essential: only the necessary components, Web integrated; nothing else

 

The world from my antenna:

 

 

Current set-Up:

Radio: Main: Icom 7851 and 7700 HF + 6m, 200W;

Backup: Icom 756 HF + 6m; 100W SSB 50W AM

Microphones: Heil PR40 combined to IC7851, Heil PR781 coupled with IC7700, Icom SM20 coupled to Ic756

 

 

The match between these two components appear to be really greath; in the setup for my voice (suggest to test on the dummy load the effect in your case)  I use for:

- Heil PR781: Bass: - 2, Treble +4 

- Heil PR-40: Bass +2, Treble +5.

In both case mic gain is kept nearly at 3 o'clock, compressor at 12 o'clock (You have to see 8d to 15db occasional max peaks while speaking) and drive knob placed to keep the ALC needle in the range of the middle - upper side of the range and always well below the edge.

In these conditions get alway excellent feedback on radio received quality and even some video clip by return to let me ear the strenght and clarity of the voice.

Time after time I understood we just need not to follow the temptation to pump up the mic gain and compression staying well below the alc red zone to obtain very good quality.

I like very much the IC-7700, I love the commands layout with everything intuitively available, reasonable low complexity and extreme effectiveness.

I am very satisfied with selectivity and sensibility performances of this radio which, despite the wide usage of DSP algorithms, is always capable to provide a very natural sound free from metallic effects or synthetic non natural feelings. You can shape the filters exactly as You like with unlimited combinations in a straight and intuitive way focusing the signal You want to ear on the spectrum and klliing anything else. Any noise can be effectively reduced any splatter can be heavily limited not to talk about the notch filter which is litterally outstanding. There is a lot to say about this radio which has an incredible potential.

If You really learn how to use it at a full extent you will hardly change it.

 

Antenna system:

Quick spotting: Vertical antenna Cushcraft R8,

DX: 3 element Ultra Beam UB50 6-40m

Low Bands: various wires in multiple shapes across 40-80 and 160m:

  • 40-80m Alpha Delta DX-DD,
  • Alpha delta DX-LB 40-80-160m.
  • Homebrew full size dipole for 80m (details on project, simulations and test below)
  • Double Zepp (doublet): 10-80 m (project and simulations below)
  • Inverted L for 160m band (details on project simulations and test below)
  • Pennant receiving antenna for 160m band (construction is almost...done)
  • Fan dipole 10-15-20-40-80m, multi resonant dipole; testing and comparison with Cushcraft R8

 

New Projects; simulations, planned developments and practical test of new builded antennas

Antennas; definitely attracted me since early childhood; I like to investigate and try new ways to achieve better performances despite typical constraints by environmental conditions.

I am always studying new options and ideas to cover in a more efficient ways HF bands and at the moment I am engaged to elaborate for my specific location new solutions for radiation systems enabling me to be more effective less visible and more sate with respect of the risk coming by weather conditions.

At the moment I am simulating or testing the below antennas against the Cushcraft R8 or full size dipoles as reference:   

  • Inverted L antenna for 160m band (for 160m and usable across 10-80m bands)
  • Doublet inverted V antenna feed by 450 Ohm ladder line (10-12-15-17-20-30-40-80m)
  • Horizontal Delta Loop: a mega delta loop with 55 to 56m side lenght (10-80m)
  • Vertical dipole feed by 450 Ohm ladder line (for 10-12-15-17 and 20m)

 

Cushcraft R8

This vertical resonant multiband antenna is nicely performing from 6 to 20m and is a reasonable player in 40m (you can't ask so much to a multi trapped small size vertical..); in other words it is allowing to jump immediately and listening on a certain frequency. It is OK for quick hunting and non extreme DX with the radio power and is offering a nice solution in all cases it is not necessary to point the beam

In 40m band I experienced the wire dipole to be superior in performance almost in all azimutal directions despite a slight directionality ("bean" radiation pattern) of the inverted Vee configuration (right picture). The R8 is an easy reference while testing the performances of antennas what I am usually building

 

Alpha Delta DX-DD dipole:

I am very satisfied; it is a true performer in 40m despite not being installed in absolutely excellent contitions.

Always very strong signal (continental level) TX and RX and greath feedback in DX outside Europe; in these cases with 400 to 500 W It is possibleto reach almost every country in the world.

The inverted Vee dipole is installed with the apex below the ground plane radials umbrella of Cushcraft R8. Despite that the dipole is clearly overperforming the R8 by 2 S points as an average being less noisy too.

From a number of signal report and tests with SDR stations the alpha Delta was in all cases showing better performances in comparison to the vertical.

About 80m the two resonant coils are in facts quite efficient which is turning in to a sharp spot of about 40Khz maximum; out of this window the antenna it is not usable so -be aware- You are going to be just present in a 80m frequency slice not to generate unreasonable expectations.

Afterward I upgraded the wire system to an Alpha Delta DX-LB to test the 160m.

 

The Alpha Delta DX LB Dipole

Initially I evaluated the extra money to buy the DX LB not worth the additional value Vs the DX-DD in view of the expected performances obtainable by such a short wire; after some time not being able to operate in 160m I became very curious to taste this special band and once by chance I had an unexpected opportunity I bought this dipole and mounted as inverted vee with apex at approx 14m above ground;covering the whole 40m like the DX DD with same good performances.

In 80m tuning was made by acting on the wire and resonance obtained across 3640 -3680.

With radio tuner it is possible to cover something more, on the other side, being the SWR curve very sharp (in my installation conditions) I can enlarge the operating range just about 10KHz more so that finally the covered band is about of 50 KHz maximum.

I rather focused my efforts in 160m to make the dipole resonant over the whole phone range (below see the picture showing the two resonant coils for 80 and 160m).

In 160m the dipole is capable to work in a 10 KHz bandwidth and I tuned It between 1840 and 1850 which is the phone slice according to the band plan in Italy. In this thin range the antenna is perfectly resonant and do not require tuning support to work. I had nice contacts at continental level with 150W (typical noise at S7 to 8) without extraordinary propagation conditions; I am going on with tests with interest in this very special band hoping to get advantage of better propagation conditions.

I also tested the wire with some power in 160m and the antenna is sustaining the challenge with no problems at all showing strong signal around Europe (warning my ROS during test in QRO is 1.1-1.2 across the phone range).

Humidity and rain are definitely affecting ROS; the antenna is clearly influenced by the increased capacitive coupling once ground is wet and resonance is lowered by 20 to 30 KHz with rain in my specific installation conditions.

In my opinion not having the possibility to install mega loops or other antenna systems requiring necessarily wide spaces the AD-LB may deserve a trial and offer a reasonable performances in limited spaces if you are able to put the apex at least at 15 m above ground level. I believe by moving the apex up to 30 or 40m the performances would surely improve, in my case I cannot reasonably ask more, this antenna allowed me to be present with good satisfaction in 160m.

A general comment about all Alpha Delta dipoles: They are very well build with strong materials and without BalUn; By removing the original central unit and replacing it with an high quality low loss 1:1 BalUn the performance improved in terms of signal noise ratio. As well, especially in 160m, transmitting with 500Watts I could avoid to loose my WIFI internet connection due to -most probably- common mode current radiations returning through the long coax cable..

After some time, suffering the technical compromise, these honest dipoles pushed me to improve the performance of my station evaluating alternative solutions aiming to

  1. enlarge the bandwidth in 80m and to

  2. better perform in 160m.   

 

Building a full size dipole antenna for 80m band

Alpha Delta DX LB is definitely touching 80m and 160m (=the portion of 160m interesting to me) BUT the point is always with the bandwith in 80m.

These dipoles allow very reasonable performances on the other side especially in 80m the band is definitely too tight (=just 40 Khz typically).

Therefore the need to do something better with smoother SWR curve by building a monoband full size dipole. It will be 40m overall with the aim to achieve 120Khz bandwidthwith ROS below 2 which would enable me (with tuning support) to operate over 140-150 Khz as a target: let's see what can be done.

I selected and procured the ingredients from far distance to build my monoband full size inverted Vee dipole for 80m:

  • 41m heavy duty top quality wire with central steel core and silver-copper litz external diameter of 2.1 mm: HFW-2 heavy duty wire
  • Ceramic isolators
  • inox steel hardware as necessary to lock the wire without mechanical stress
  • Balun 1:1 by Kelemen 2KW rated (BalUn is fundamental for the proper bahaviour of the antenna!)

 

 

 

 

 

 

 

 

 

 

 

 

by simulation each arm is expected to be phisically about of 19.03 to 19.05 m long (we'll se what the analizer will tell while carefully matching the resonance).

Estimated expected gain in my installation is 3.4dbi at 33 degrees and 6.9dbi at 90 degrees.

 

 

 

Let's see the expected bandwidth with apex at about of 14m-15m, in theory and practice:

In theory would be about of 60Khz and bandwidth with SWR< 2 of more than 120KHz

Realisation in practice: First of all the estimated lenght the calculated estimated wire lenght turned out to be very precise at resonance and finally I fixed the arms exactly at 19,04 m

Resonance and Bandwidth: With antenna analizer antenna has been tuned with center resonance at 3.706 MHz and SWR is below 1.5 within more than 100 KHz: (105KHz in practice)

Within 3,6-3,64 Mhz and 3,75-3,8 Mhz the radio tuner is matching perfectly the antenna wich is operating fully across 3,6 and 3,8 Mhz or the whole 200Khz SSB range according to the band plan here in Italy.

Tested in QRO with the Expert 1KFA across the 200Khz and the dipole is behaving perfectly.. Here is the picture of my new dipole mounted below the Cushcraft R8: Nearly impossible to see it!

The dipole is basically INVISIBLE and we all know the best antenna is the one that neighborhood simply do not know it is existing.

Concerning performances to tell the truth the antenna is behaving above my best expectation with ceramic isolators at approximately 5 to 6 m above ground.

The Kelemen Balun is doing a really good Job (tested with challenging QRO) and it is really low noise too. The noise floor -in facts- is on a level of maximum 3 almost always and less frequently 5 S points,

Received signal very very strong; almost always above 9 + / 9+10 tipically and more. I have got also very strong signal reports above S9 everywhere in Europe with the power of the radio.

On 27 April I had very nice DX and worked W1AW/P1 with 150 Watts of the radio, Virgin Island, Asiatic Russia; 

What to say more, I am reasonably very satisfied for the time being and look forward to continue in testing activities.

All in all If You have the space the advantage of the the full size dipole against a trapped shortened one in 80m band is evident; bandwidth would be extremely limited by traps and the antenna rapidly unusable outside the 30-40KHz of coils resonance.

Inverted L antenna project for 160m band

To achieve better results with respect to the AD DXLB I think to the best solution I can afford by space limitations and no need to invent here considering the experience and the suggestions of many successful OM on the king band.

I started to modell a quarter wave inverted L with a vertical development of 16 to 20m (using the 20m pneumatic column to pull it up) and using as ground plane the house roof (approximately 400 square m fully copper made roof).

At the moment I am optimizing by computer simulation the wire lenghts and comparing this option with a wire-made vertical and in both cases I assume to utilize as ground plane the entire copper roof of the house.

Option n.1 Inverted L having vertical development of about 15 to 17 m

 

For the inverted L I would use the usual antenna wire applied to the column while the horizontal portion would be placed in direction to one of the surrounding trees studying the best possibility available.

Copper roof as ground plane

I would use an heavy duty 1:1 Un-Un (like the DXE-VFCC=H05-A) to connect the antenna hot pole and ground plane respectively to 3-4 m of coaxial cable long enough to reach the antenna tuner (Palstar HF Auto) right in the attic below. 

The key of everything is that tuner will match the antenna load through a very short low loss coaxial cable which will make negligible the losses by experimenting the antenna behaviour over the whole Ham radio frequencies from 10 to 160m

As always the most important point: I expect this antenna to be almost completely invisible!

 

Expected performance of inverted L for 160m on other bands

As we all know there are a couple of point with such kind of antennas to be taken in to consideration; the first is to keep to a reasonably high level the impedence not to make the tuner job inefficient and difficult; the second is to try to make the vertical section of the L shape as long as possible to allow the lowest take off. 

After some practical evaluation of existing constraint I wanted to stretch the overall radiator lenght to about of 51m which is allowing to achieve the load above 22 Ohm whith a Vertical section of about 16.5m and Horizontal-sloping of about 35 m. The ground plane surface of the roof It has been modeled by a number of wires reflecting the shape and the size of the copper roof which is a simplified model of the copper roof surface in the reality.

In that respect I do expect in reality to have a much more efficient ground plane with respect to the simulated condition.

Following the resulting antenna simulated by MMANA-GAL

 

 

By simulating across 10 to 160m I found out following radiation pattern as a result:

 

 

 

 

 

 

 

 

 

 

 

 

Well; in few words by tuning this inverted L It seems It would be throretically possible to obtain an interesting multiband vertical-horizontal antenna able -in more that one band- to outperform the Cushcraft R8 trapped vertical.

I will take the Cushcraft R8 as a reference (except for 160 and 80m obviously) during experiments and I am very curious to see the outcome.

 

Dreamer Option for 160m band is a vertical optimized to have a reasonably low take off angle.

The vertical thin cable vould be about of 54m (HFW-2 is 22g/m therefore 1,2 Kg in total for the cable weight plus ceramic isulator ...).

I vould need a nitrogen balloon of about 4 to 5 cubic m to elevate the vertical wire and the advantage in theory It woul be not negligible; 1dbi gain at 17degrees of take off and better performances below 30 degrees elevation with respect to the inverted L as it is possible to see from simulation and related comparison by overlappint the related radiation patterns.

 

The coaxial cable would pass through an automatic tuner close to the antenna feedpoint connected using a choke (like the DX Engineering DXE-VFCC-H05-A) to feed the vertical wire radiator and connect the ground plane (=copper roof).


My Inverted L Antenna for low bands: test on air

To make a long story short I discovered too late I could transform my whole house in to an extremely efficient and stealth antenna for 80 and 160m bands !!

Below You can see the practical implementation of the Inverted L antenna as described and simulated before.

The wires lenght resulted slightly different as I could get advantage by some minor difference with respect to the estimates made and overall radiator development resulted to be about of 52m.

The bottom ceramic isulator is kept in position by three non conductive wires and antenna is connected to the hot pole of the vertical feed line current choke while the ground is connected through a braid to the wide copper roof.

Please disregard the naif positioning of the DX Engineering UN UN in the below picture; it was just a temporarily test set up!

 

Herewith some preliminary results which will get advantage by further extended verifications and test.
First of all I tuned the antenna on lower bands 40-80 and 160m. It has been very easy and straightforward to achieve the resonance (I didn't took to much attention to other bands so far but I have to say it is also tuning everywhere except 20m) and I am happy to share the obtained results

Inverted L in 40m Band Vs Cushcraft R8:
The inverted L is showing generally an advantage by 12 to 15 db in RX and TX against Cuscraft R8 almost in all cyrcumstances.
In some case the gap is a bit lower probably when signal direction falling in to the minimum gain spot of the multi-lobated Inv.L radiation patern Vs the uniform omnidirectional radiation pattern of the Cushcraft. All in all the inverted L seems to be definitely a more efficient solution in 40m band with respect to the R8. The disadvantage: Inverted L is not an isotropic (=omni directional) radiator showing some weak spots at both Rx and Tx.

Inverted L tuned on 80m Band Vs full size resonant dipole:
Results here are controversial but substantially in line with expectations out of simulations.
For some azimutal direction the Inverted L seems to overperform the dipole by 2 to 8 db; (by tests through the MDS receiving sites  distributed across Europe). This situation is probably reflecting the advantage that the Inv.L antenna is offering over the two max gain lobes (the Inverted L is showing two main lobes perpendicular to the geometrical plane defined by the wire) . For instance
experimental results seems to show higher performances between 310 and 320 degrees against the dipole which is exacly the direction of UK in my case.

In other cases the Inv.L is below the dipole by 2 to 5 db especially when received signal is coming from side directions with respect to the main gain lobe. This is also consistent to the directive behaviour of the Inv.L against the omnidirectional radiation pattern of the dipole which is also giving  his maximum gain on higher elevation angles (=more effective on the shorter distance bounces below 6-800km).

One thing it is absolutely sure: inverted L is definitely more noisy than the dipole in 80m band and this is a fact.

Depending upon cyrcumstances I found a typical noise floor of 5 to 7 points with the Inv.L Vs the 3-5 as an average of the dipole and i found the dipole in more than one case more effective in receiving some weaker signal with more clarity and strenght as far as radio read-ability and quality of the correspondent is concerned.

Inverted L tuned on 160m
My only reference until now was an Alpha Delta DX LB dipole in 160m band and also need to clarify that, as it frequently happen to many of us, the antenna was placed low above the ground (=apex at 16 to 18 m) which is typically associated to an omnidirectional baloon-shaped radiation pattern with a maximum gain at 89 degrees above the horizon.

The noise level is always relevant on this band and I found no significant differences between the two antennas from this point of view.
A relevant difference was found in TX performances; here I have been really impressed by the effectivemess of the inverted L
In the past I usually operated with the amplifier on 160m while with this antenna I had the chance to communicate with UK, Russia with just 150W of my radio with 10 and 20 db over 9 report.

Before I could barely float above the noise floor typically at 8 or more frequently at 9 with 400-500 watts and had difficulties to be understood also.
Therefore in 160m the performance of this antenna is definitely superior with a consistent and clear gap with respect to the dipole.

I guess this result is also possible thanks to the wide copper surface of the roof which should work as an extremely effective ground plane allowing the antenna to become really performing and efficient.

Extensive test sessions Dec-2014 / Jan-2015 at Low bands:

During my holiday I had the chance to widely test the inverted L with 450-500 W over the 80 and 160m band across a three weeks period. With this antenna I tried on purpose various contacts in QRP (5 to 7 Watts) on continental level in 80m and I have been surprised by the very good reports obtained in a range of 1.000-1.500Km what I associate to a reasonably high efficiency of this wire radiator system. I also tested in detail the resistance of the groud plane (copper roof surface) which turned out to be in facts fully short cyrcuited copper layer (at 25 m distance from the base of the vertical section of the wire the copper surface is showing 0.1-0.2 Ohm resistance).

With 450W in 80m I connected everything what I had the chance to receive from Japan to New Zealand Asiatic Russia USA and Caribbean while in 160 m band beside Europe and middle East contacts I could get LOTW confirmations from USA stations. In this last case the noise and the absence of adequate receiving set-up has been a severe limiting factor not allowing me to detect the presence of signal below the thick noise layer.

In conclusion I can say that this inverted L is definitely a very good transmitting antenna (of course It is depending upon the specific installation) for low bands, at the same time, a reasonable set up for 80m -not to talk about 160m- band cannot be rated as satisfactory without a very well studied receiving system which is undoutably the weak area of my set-up at the moment: I will focus toward this in near future aiming to identify a compact but efficient solution for a receiving system for 80 and 160m bands.

 

We are coming to the pennant RX Antenna: 40-80-160 m bands

Nothing to say and nothing to invent, the pennant antenna is a triangular toop closed on a 880 - 900 Ohm non inductive resistor load; I used the below configuration placing the load on the vertical section (the base of the triangle) and feed point at the apex. Peak of Rx gain is toward the feeding point; this antenna has a typical cardioid sensibility pattern

 

 

 

 

 

 

 

 

 

 

 

 

I closed the loop on a load made by (see above right picture) four 220 Ohm ceramic resistors in series (type OY221KE).

As It is highlighted by more experienced OM since many years the usage of ceramic resistors It is absolutely preferred instead of carbon based resistors.

Ceramic composition allows better reliability and more robustness in case of static overvoltages along the wires which is an even more frequent and typical risk in case we build long beverages.

The RX loop is pointed to USA at the moment (during testing and fine tuning) .

You can easily build the matching trafo at the feedpoint; to do so You may easyly proof by very simple calculations that the conversion factor between primary and secondary of a trafo for the impedence is a quadratic law of the winding ratio. In this case willing to match 50 Ohm to  880 Ohm ( 880/50 = 17.6) the ratio is about of 1 to 4. So You may first of all make 2 or 3 rounds to connect the 50 Ohm coax side and -respectively- 8 or 12 that will be connected to the antenna side. 

I did it winding around a binoculaf ferrite (BN-73-202) 3 rouds toward the 50 Ohm coax side and 12-13 turns on the ~900 Ohm antenna wires. You have to measure the result and eventually increase by one the turns if it is necessary. Below the prototype version in a temporary installation for measurement tuning and first tests

This period of the year (April-May) the 160m band is not very populated like in winter season, on the other side I will continue the test activities to optimize the installation and therformances of this receiving loop and will select an appropriate preamplifier (actually not involved in the preliminary phase of the project) to further improve and tune the performances.

 

Doublet antenna project for 10 to 80m band (double Zepp)

The doublet antenna, also known as Double Zepp antenna, is within the easyest and oldest antennas developped in the history of radio. A number of versions came out in the years by cutting in to specific lenght the feed line and the arms trying to find compromise resonance in OM frequency window (G5RV for instance but You have in practice to use a tuner). Someone else claim to have discovered some magic lenghts to optimize radiation patterns toward low take off angles; well what to say, by my side simulations are telling It is rather useful to follow the original recipe to build this antenna: just cut the arms as long as You can, place it as hight and free as You can afford and avoid critical lenght for the feeding line (to avoid critical impedence values for the tuner across the bands of interest).

This antenna is -by definition- non resonant and must be conveniently feed by a ladder line to make SWR losses negligible while a (balanced) tuner is applied right to the base.

Since I do not own a tuner with balanced output I use an heavy duty external 1:1 current balun to couple the antenna ladder line (450 Ohm) to it trough a short low loss coax cable guided throug the wall.

The architecture in my case is driven by the space available in my property so I decided to elevate a ladder line for about of 16,4m eight above the roof and then pull two sloping arms of about 22m each.

At the base the ladder line is connected to a balun (I selected for instance the DX Engineering DXE BAL05H10AT) and then a coaxial cable (just about of 2 to 3m low loss Ecoflex 10) what I use to access the tuner in to the attic (Palstar HF Auto).

The tuner is working in automatic mode right at the entrance of the coaxial cable in to the attic and then a 25m long low loss (Ecoflex 10) cable is connecting the tuner to my radio.

In this way the radio see constantly a perfect match trough all the HF bands 10 to 80m; the nominal insertion loss for this tuner is declared to be in the range of some fraction of db and the 2m of low loss coax to the balun, the balun itself and the ladder line would increase further the losses. All in all I estimate in worst case the losses between 1 to 1.5 db across the whole HF bands as a worst case from 80m to 10m depending upon the mismatches challenges the tuner will face with. Considered that simulations are showing impedence values never below 48-50 Ohm through all the HF band, based on lab test made by ARR I do expect this system to be reasonably efficient (power losses not above a few percentage points in worst case).

Below You can see the picture of the architecture of this project:

The natural question mark at this point is linked to predict how good this antenna may behave across HF bands and It is coming without saying that I had a lot of fun simulating the performaces of this antenna across the 10 - 80m.

As always I take a lot of time evaluating upfront distances inclinations and theoretical point to hook the wires (thanks to Google map by the way) so I am able to compare -by simulations- various scenarios prior to start the assembly preventing  inconvenient surprises in the middle of the activities.

Note: I use as antenna wire the HFW2 cable and I like to share with You the results (by MMana Gal) which seems to be quite interesting in perspective of future experimental tests in practice.

As You all know better than me these patterns represent just an approximate picture of the real performances, given the relevant number of simplifications of the model wrt the specific environmental conditions.

The doublet is substantially omnidirectional in 80m band where is giving lower take off and higer gain (due to the higer position of the apex) in comparison with the full size dipole (also due to higher apex positioning) and I am very interested to see in case this will turn in to tangible improvements (the full size resonant dipole estimated gain of 6.9dbi at 90 degrees and 3.4dbi at 33 degrees) .

Here there is no match with the inverted Vee AD DX DD in the sense that doublet -thanks to a more favorable installation- is expected to perform better in gain and elevation, on the other side, the UB 50 is the absolute winner and gave proof already of excellent DX capabilities in 40m band with the power of the radio.

 

 

 

 

 

 

 

As we can see this antenna is offering quite some interesting performances in theory especially in some of the HF bands where simulations are telling it is absolutely worth to give a try on the real field to this simple wire.

I am going to test this architecture and will report my experiences.

 

Horizontal multiband (BIG)delta loop antenna:  

This one is most probably an antenna I will be unable to test due to his huge size which would make the installation impractical in a typical residential area.

It would require a country side open area to be installed properlyusing tall trees.

The architecture is in facts very simple with each side  of the triangle of about 56.4m lenght.

With approximately 170m antenna wire a balun and an automatic tuner we may have more than just areasonable suspect that this is an outstanding TX antenna.

(Simulations are showing an SWR level reasonably low assuming to use a 4:1 balun choke across 10-80m, so probably a tuner may not be absolutely necessary)

I am saying TX and not TX/RX because based on what I can see from rough simulations about 360 degrees gain figures the noise level will be quite high trying to listen a specific station.

Let's have a look and some remarks by simulating the performances across HF bands.

The antenna is suffering being simulated assuming a 20m agl installation

The maximum Gain in 160m band is 8.4 dbi @ 89.4 degrees so we are heating up the clouds -on the other side- It was largely predictable given the limited altitude of the installation.

 not a big deal with respect to the inverted L which is remaining the clear winner on the Top Band with 1dbi @ 20deg.

small directional behaviour with interesting gain figures.

interesting gain figures with a multi lobes pattern having maximum gain @ 29 degrees take off. (figures written in the drawing related to the jellow take off mark line)

Now the performances in 20m band

In 20m the antenna is behaving like a set of beams pointed at 360 degrees with a take off lower than 14 degrees and nearly 14dbi peak gain. Gain figures in the drawing are related to the jellow take off line.

 

 

 

 

 

 

 

 

 

On this band the loop is showing a true high gain flower with a low 10 degrees take off (marked with a jellow line)Peaks of 14.7 dbi (front) and 10.7dbi (back) with multiple lobes 6, 7 and nearly 9 dbi

 

 

 

 

 

The gain figures in above 15m radiation pattern are associated to the jellow line take off (9 degrees); multiple beams radiation lobes well above 10 and 11 dbi with a peak of 13.2 dbi and secondary lobes with 8 and 9 dbi peak gain combined to a low take off angle.

 

In 12m band above marked gain figures on the drawing are reflecting jellow line take off elevation of 7.5 degrees.

 

Some Remark:

After this sequel of theoretical simulations we may summarize the results obtained assuming to operate in HF bands using and inverted L, a doublet or an horizontal loop:

First of all I have to say that this sort of horizontal Mega-Loop seems to be a really amazing TX antenna and It is the clear winner between 10 to 80m behaving in more than one band as a true nest of beams pointed at 360 degrees.

As a side effect we may unfortunately expect this antenna to be terribly noisy by which the coupling with reasonably good directive Rx antenna would be a must.

The inverted L is doing the Job in 160m band and despite the non isotropic behavior (is showing a multi beam pattern) I guess may probably outperform the Cushcraft R8 in more than one cyrcumstance; I look forward to test this during practical sessions.

What is really making me absolutely curious is the performance of the non resonant inverted Vee doublet. In case theoretical simulations would be reflected in the pratice of my specific installation at a reasonable degree we may expect to have a really serious multiband quasi omni directional (it is multi lobated pattern in facts) with performance indicators (=gain / take off angle) really interesting despite the relatively easy and simple construction.

It is true; We have to highlight that to make this non resonant doublet system working a well made (=based on big rolling variable inductors and capacitors) tuner placed very close to the ladder line feed point is needed (need to be full automatic probably) and an external balun is needed which will make the resulting system NOT a very cheap one.

We will see; I need to find out real performances in practice by real time switching in TX and RX the doublet and the Cushcraft R8 taken as a very popular reference.

 

 

Vertical dipole 5 HF band coverage: How to cover 10-12-15-17 and 20m band without ground plane or radials ?

Today I like to share another project which is another basic antenna extremely simple and easy to make.

We just need to procure as key ingredient for our scope:

- approximately 10m of the best quality copper wire (extremely strong mechanical characteristic not needed in this case for obvious reasons)

- ladder line 450 Ohm (in my case I needed approximately 25-26m); a

- fishing pole or alternatively a spiderbeam like fiberglass pole (this last one is probably more robust for long term fixed installation),  

- the usual 1:1 heavy duty balun (if Your tuner is not balanced), I use a DX engineering DXE BAL05H10AT

- a few m of coaxial cable (as short as possible to connect the feedline from the balun to the tuner inside the attic)

- an auto tuner (I use a Palstar HF Auto) by which a coaial cable is going to the radio at the shack (It is approximately 25m line in my case) .

In my case I assumed to place the vertical fiberglass pole at the place of the Cushcraft R8 currently mounted on a 12m metal pole.

The fiberglass pole is going to sustain the vertical dipole wire and ladder line is moving dovn almost 45 degrees wrt the vertical.

Below -as usual- the architecture of the antenna system in my specific case

with a phisical lenght of approximately 10m (5m + 5m) this antenna it is in principle able to provide reasonable performances between 10 to 20m covering 5 HF bands.

The base of the fiberglass pole is mounted over the 12m metal pole above the roof (plus 5m-6m above groud level).

Let's see the results of simulations; In each band I evaluated the estimated rough maximum gain in above summariized conditions (5+5m arm lenght) and associated take off assuming to keep the lenght of the dipole of about 10m; radiation pattern are referred to this dimensions.

I also compared the gain assuming to increase the dipole lenght from 10m to 12m (=arms of 5 and 6 m lenght) and reported respectively the two plots on the right side to see in case increasing the dipole lenght would bring an advantage.

10 m Band: 5dbi at 6 degrees

 

It is interesting to observe the gain sensitivity wrt the lenght of the vertical radiator lenght in 10m band; by increasing the arm lenght from 5 (red plot) to 6m (black plot); increasing the total lenght to 12m; the gain is increasing by 0.51dbi while take off elevation is theoretically unchanged.  

12m Band: 5.77 dbi at 6 degrees

In 12m band beside radiation pattern I simulated the plot comparing two lenght (respectively 5m in red and 6 m in black).

It is turning out that the vertical dipole 12m long would apparently have a maximum gain of about 6.19 dbi at 7 deg take off Vs the 5.77 dbi of the dipole 10m overall at 6degrees take off.

When we are able to increase by 1m each arm we would apparetly get a theoretical advantage of about 0.4 dbi

 

15m Band : 4.3 dbi at 8 degrees

In 15m band the advantage of lenght increase from 5 to 6m is just 0.29 dbi with same take off.

 

17m Band : 3.43 dbi at 8 degrees

Interesting result in 17m band: in this case trying to increase the vertical dipole lenght in my specific conditions (specifically simulated model and feed line lenght) do not bring an advantage and gain is degradated by 0.33 dbi with no change at take off angle.

20m Band :  3.22 dbi at 11 degrees

 

In 20m also seems to be an advantage to increase if possible the vertical dipole lenght wich would bring a non neglible theoretical gain advantage of about 0.63dbi with same take off.

 

Few conclusive remarks on vertical dipoles prior to field test.

There are undoubtedly a number of advantages by thinking to build such kind of antenna: It is very simple to make and light weight (which is making the installation less problematic and easy) and do not require radials to be an effective radiator.

As far as performances are concerned this antenna is offering an average very low take off across all covered bands by which we may expect excellent results in DX activity.

When we consider the relatively low cost (if You own a tuner already) with respect to commercial vertical antennas the vertical dipole radiator appear to offer a really competitive solution.

It is covering five bands from 10 to 20m with take off angle (below 10-11 deg in all cases) and an estimated minimum gain of 3 dbi in 20m; 3.2 bdi in 17m; 4 dbi in 15m; 5.5 dbi in 12m and 4.8 dbi in 10m assuming to reduce by 0.1 or 0.2 dbi the tuning plus balun losses.

By having the oportunity to make the vertical dipole a bit longer (tested 10 and 12m) this bring an advantage in gain in the order of 0.3 to 0.5dbi in case of the geometry I have simulated.

Nice theoretical results; It would be interesting to verify in practice having enough spare time to do it.

 

Fan-Dipole antenna

While the doublet has the advantage to work across all ham bands It cannot be underestimated the fact that we need a balanced tuner and in addition a twin leads line need to be used which is also requiring some attention and it is not always practical/easy to handle in all cyrcumstances.

In following notes I will summarize the results out of some testing session using a fan dipole multi resonant antenna --- to continue. 

 

The ULTRABEAM UB-50 antenna, comments by user 

This unbelievable antenna is working as full size 3 elements between 10m to 20 m with continuous frequency coverage.

With two additional passive elements for 6m is working as a 4 elements in 6m.

It is also allowing to cover 30 and 40m as bended full size dipole; basically there is no significant performances drop with respect to a full size rigid horizontal resonant dipole.

Until the installation of the UB 50 I was generally operating with the 200W of my radio and engaging the amplifier for some test; since I have this antenna my amplifier (Expert 1K FA) is always switched off.

Image of my Ultrabeam UB-50 on a 22m telescopic pneumatic column (2.5m massive alluminium mast) mounted on the roof resulting approximately in to the capability to elevate antennas nearly at 30m above ground level.

Interesting is also the capability to retract the structure in a way that nobody can see the antennas in case the station is not active but even more It is full safety "storm proof" solution when I leave for long periods abroad (almost constantly).

Also I like to test the performance in various bands by tuning the elevation (AGL) of the antenna according to the frequency of operation and the results are sometimesinteresing and showing how a perfectly (elevation above ground) tuned antenna installation may guarantee excellent performances.

On the very top of the mast there is a Sirio Gain Master antenna which is barely visible in the above picture (7.2m tall!); elevated at 29.5m above ground level). You may better see the detail in the zoomed picture below:

 

This antenna I wanted to test just as pure curiosity as I like very much to try in practice and compare.

It is a vertical dipole covering 10m band completely and 12m (this last band with tuning support).

The Gain Master vertical -may be due to the good installation conditions (=nearly 3 times the wavelenght of operation) is performing quite well.

It is interesting to switch -during DX sessions in 10m-the Cushcraft (which is installed at approximately 13-15m below) theGain Master and the UB50.

I made many tests and results are controversial concerning the performances of the two vertical. I suspect that the different take off (probably lower for the GM) in 10m band may play asignificant role case by case depending upon the different angle of propagation toward the antennas which in some case is giving the advantage to one or another. The only think which always confirmed is the superior perfrmances of the Ultrabeam.

In some cases (for some incidence angles) the Cushcraft may perform better while in other cases the vertical dipole is offering stronger signal but definitely there is no one out of the two systematically outperforming the other.

 

Outstanding performances; believe it or not the UB 50 is a true DX Gun with just 200W PEP SSB.

 

 

ULTRABEAM UB 50 antenna

I am not known to be a guy which is easily kept by enthusiasm, at the same time, I have to admit I have been unusually surprised by experiencing the performances of this Ultrabeam antenna.

I just listen (as I like very much) the messy pile up and meanwhile quietly pointing the beam precisely in to the target direction, testing the front and back and may be also checking the signal drop against the vertical.

Then I am precisely checking the SWR and (depending upon humidity or other climatic conditions) just tuning with the control box the perfect resonance in a way that the needle is even not moving and the whole power is transferred to the antennawith almost no reflectionsat all.

When You get used to have almost no SWR You do not accept even a small 1.0004 to occur!

Then It is fun because I challenge myself to break in at the first shot by "placing the call" exactly at the right time. If we do that right and we "feel the pileUp rhythm" there is no need to call in twice (It is a sort of ZEN discipine hi).

In many cases I break in on the spot, get and give my report and go away using the 150-200W of the radio receiving every time very strong signal feedback.

My experience is saying, by S-meter measurements, that this antenna has an excellent F/B (=4 to 5 S points) not to talk about front/side and gain is absolutely brillant.

The ability to switch in few second 180 degrees (by swapping director with reflector) is very nice allowing quick check long-short path limiting the use of the rotor which is allowing very fast pointing time capabilities too.

In 40m is also performing extremely well in comparison to my lovely inverted Vee Alpha delta dipole; when I get a 5/9 with the inverted Vee I can easily receive a 5/9+10 or 9+15 report with the folded rigid dipole of UB50 (to be fair the UB50 is enabling to keep the folded dipole well above the inverted vee apex).

 

Look forward to meet you on air soon!

I will be more than happy to give confirmation (via EQsl and LOTW) by return.

 

Greetings from Italy, good DX to You all

73's and have fun experimenting and trying ...  

 

de IZ2XMK, Luigi.

 

 

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QRZ Logbook Summary for - IZ2XMK
Latest Contacts for IZ2XMK at QRZ.com
dedateband mode grid Country op
OK8UN 2018-01-14 80m SSB JN99BT Czech Republic Alain Kieffer
FR4QT 2018-01-14 20m SSB LG78PW Reunion Mario Xavier LAPORTE
VK3TJK 2018-01-14 20m SSB QF23CH Australia Tim Krause
XT2AW 2018-01-14 20m SSB IK92FI Burkina Faso Harald Becker (DF2WO)
ZL2SDX 2018-01-14 20m SSB RE78NV New Zealand Darren P M Hill
BG7BES 2018-01-14 20m SSB OL67DN China Long Teng
6O6O 2018-01-14 17m SSB LJ22NL Somalia Kenneth Opskar
YJ0CA 2018-01-14 20m SSB RH34LP Vanuatu Chris Ayres
DF1WH 2018-01-13 80m SSB JN39PS Germany Thomas Faller
KJ4MSR 2018-01-13 17m SSB EM73IR United States Jonathan P Maples
VA2XT 2018-01-13 17m SSB FN04JM Canada Alain Jacques
VE1KF 2018-01-13 17m SSB FN84DN Canada Lawrence Brent Rudderham
KD2KW 2018-01-13 17m SSB EM13LE United States Kenneth E Mitchell
HR1/PDLCT 2018-01-13 17m SSB EK64JC Honduras
KD2JQK 2018-01-13 17m SSB FN20LT United States Steven G Ruff

Book Totals: 3046 qso's   880 confirmed Get a free logbook at QRZ.COM


c
DX World Award#1694
Granted: 2015-04-08 13:50:03   (IZ2XMK)

Endorsements:
  • Mixed Phone
World Continents Award#351
Granted: 2015-01-15 17:50:28   (IZ2XMK)

Endorsements:
  • 5 Band Mixed
  • 10 Meters Mixed
    12 Meters Mixed
    15 Meters Mixed
    17 Meters Mixed
    20 Meters Mixed
    40 Meters Mixed
  • 5 Band Phone
  • 10 Meters Phone
    12 Meters Phone
    15 Meters Phone
    17 Meters Phone
    20 Meters Phone
    40 Meters Phone
Grid Squared Award#341
Granted: 2015-01-15 17:50:10   (IZ2XMK)

Endorsements:
  • 20 Meters Mixed
  • 40 Meters Mixed
  • Mixed Phone
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