40m wire antennas compared

Before going on holiday I managed to get some life into my old C-Pole using a new home made choke. I re-tuned the antenna (with some challenges) but did not get a chance to use it. 

In the past I did use it quite a bit and was pleased with the results but as always - this does not tell you a lot. HF conditions vary too quickly and dramatically to base any evaluation on single antenna experiences. You really need simultaneous A/B testing.

A gap in my schedule allowed me to go out and do some testing of different wire antennas for 40m. I ended up testing a C-Pole versus an end fed halve wave more or less vertical and the same C-Pole versus an inverted V dipole.

Test setup

I used two identical WSPRLite beacons that transmit with 200mW on the WSPR frequency. 

• The C-Pole was set up so that the feedpoint was at approx 2m above ground (that would be your typical setup with a 12m pole, like the Spiderbeam I have - with the top of the antenna at 11m). 
• The EFHW was attached to my 18m pole and therefore almost vertical. The last 3-4m I set up sloping so that the feedpoint was at approx 1.5m above ground.
• The Inverted V was set up so that the feedpoint/apex was about 13m high. 

The test period was the end of the afternoon. Not the best time for 40m and certainly not the best time to test DX performance. However it was the time I had available. 

C-Pole meets EFHW vertical

The first run was the C Pole vs the EFHW vertical. I let the beacons run for about an hour. After that time I had:

Antenna	Transmissions	Spotters	Spots
C-Pole	15	60	328
EFHW	15	60	392

On first glance the EFHW vertical seems to fare better. It has been heard more often. However both antennas reached the same amount of spotters. So nothing too dramatic here. There is not a lot of difference in the stations that received the signals - so most of the spotters returned data for both antennas.

Now looking at the SNR reported by the spotters there is more to say about the difference. I averaged the reports per spotter to decrease the amount of data points. The graph below shows the signal strength reported (SNR in dB on the Y axis) at the spotters' distance. It looks like the EFHW (in orange) performs better.

I then calculated the average difference in signal strength per spotter of the EFHW over the C-Pole - so only for spotters that returned reports for both antennas. The graph shows the difference the EFHW scored in dB - above the line means the EFHW beat the C-Pole. 

This clearly shows the EFHW beats the C-Pole on almost all distances and sometimes by a fair margin. The outlier is S51RS at 950km. That is the only spotter favoring the C-Pole significantly.

So if you have enough height available the EFHW is the one to choose out of the two at least for the ranges tested today. This is what I expected from the theoretical analysis I did some time ago.

An interesting followup would be to see how the EFHW would perform with the same top height (sloping from the 12m pole or tree branch). With a slingshot one can easily get a vertical wire up 20m, so I would normally aim for that height with this antenna.

C Pole meets inverted V dipole

Now how about the inverted V? This one adds another element to the game as it is horizontally polarised (as opposed to the vertical EFHW and the C-Pole).

I chose a height around 13m (not fully extending the 18m pole). In retrospect I might as well have gone 2 meters lower to compare the antenna if set up on the same 12m pole as I used for the C Pole antenna. Here we have a slight advantage for the inverted V.

Running the beacons for just under an hour I had:

Antenna	Transmissions	Spotters	Spots
C-Pole	10	45	202
Inverted V	11	46	219

The inverted V got one extra shot so it is hard to tell from this first glance which one performed better. 

Looking at the average report per spotter shows that the Inverted V (in green) seems to beat the C-Pole on most occasions. 

Moving one step further the indication is confirmed. The Inverted V wins (above the line) almost everywhere. The biggest outlier again is S51RS.

Conclusions

I did not test the inverted V against the EFHW vertical directly. However looking at the differences per test, using the C-Pole as "a reference antenna", there does not seem to be a lot of performance difference within EU. I would have expected the inverted V to do slightly better than the vertical on the shorter distances (with its higher radiation angle) but that might be only noticeable on even shorter distances.

So, this time I learned that within EU the C-Pole loses against an inverted V at more or less the some top height and loses against a vertical EFHW with the feedpoint at more or less the same height. 

One question remains - as the antenna's have different radiation patterns - would any of these clearly beat the others on multi hop DX? The simulations I did previously would suggest that the C-Pole would have an advantage over the inverted V because of more low angle radiation.

If it turns out the C-Pole does not "deliver on promise" there, then I cannot see a lot of situations where I would choose it over one of the other designs. Only if the footprint needs to be minimal and height is restricted (*).

This last question requires a new test around gray line time - when I can't use my favourite test ground as it is only accessible in daylight. Something to put on the "to do list".

*) Another one: would the C-Pole beat a shortened 40m EFHW of equal height - so approx. 12m? I have such a wire with spool that I used in the past for my 10-20-40m EFHW.

One man set-up for the 26m Spiderbeam pole

In January of this year I received the Spiderbeam 26m HD fiberglas pole. It is the tallest they have and afaik the tallest you can get. Cool for low band antennas with little compromise.
I used it only a few times as I can normally get all the antennas I have on my 18m pole (or on my aluminum mast) and I simply did not have the time to build and test low band antennas.

When I did bring the mast out I was reminded of its size and weight - 2m when collapsed and an interesting 18kg. If you have a good support - like the one I build that I attach to my car, or some strong fixed pole you can tie the mast to - it is possible to set this up on your own. Otherwise you need more people. When we used it in the open field during the PACC, we need 3 people.

A few months ago I build a simple support system for my 18m pole that allowed me to set this mast up in the open field without any hassle. I have been using this more often and started to think if I could make something for the 26m mast as well. I wanted to use a bigger surface this time, but use a different structure because it would become too bulky if I just enlarged the 18m version.

Walking around in a DIY store I stumbled upon a flat roof vent. The inner diameter is just over 110mm allowing the 26m pole to slip through with the end cap on.

Now picture this thing pressed between 2 layers of wood with holes on each corner for stakes / pegs. I could just see this working. So I took this home and started working on the two layers of wood.

I chose plywood and cut two pieces approx 60 x 60 cm. I chose the bottom layer a bit thicker so I could sink the bolts I was going to use into the wood (and that way keep an even surface). In the picture you can see that I already cut a hole in the middle with the largest hole saw I have. That saw is only 83mm so I next I enlarged the hole.

Enlarger the center hole

The intermediate result - starts looking like what I had in mind

I added 4 bolts though both plywood layers and the metal, made 4 large holes (25mm diameter) near the corners and glued the two layers of wood together. Another thing I did (like with the 18m pole) is to add a fixed ring on the top of the lower segment of the 26m pole and add three guy rings to it.

(sunk) bolts through the wood and metal

Fixed guy rings

I finished the work yesterday, so today I could make good use of the brilliant weather we have at the moment to go out and see if my construction works.

Just for a comparison of size I put the 26m and 18m poles side by side with the two mast supports.

I then started setting up the 26m pole. I used four stakes in the corners of the plate I constructed. They were of different size and mostly too long as you can see. However, they still do the job.

As I hoped, the collapsed pole slipped in nicely and stayed upright - even before I guyed it. That is very convenient as it allows you to add the guy lines one by one and adjust the tension of each one until the pole is fixated and completely vertical. 

I then pushed the segments out with my 20m long end fed wire attached to the upper segment (while I was there I might as well make some contacts). I was lazy and only wanted to assess if my idea worked so I did not guy the pole on any other level. 

As you can see the pole was not completely vertical. This was due to a lack of tension in the guy lines (will put on more tension next time) and of course due to the lack of guy lines higher up. It stayed up though and I was able to make a couple of WWFF contacts in the half hour I was there.

It is easy to set up and break down the way it works now, so I am pleased. The one thing I do need to add is a small step or something else that allows me to stand a bit taller. I am 2m tall but still the pushing out of the last segments is heavy work.

Projects - Inverted V antennas for the low(er) bands

Choosing a /P antenna for 80m

My favourite antenna when working /P is the end fed half wave, set up vertically. It is easy to set up and works well with reasonable DX performance. It will not beat my portable hexbeam when working DX but that one requires more time, material and open space to set up.

The EFHW vertical becomes a challenge however on the lower bands. Now I did get myself the largest Spiderbeam pole - so a vertical half wave for 40m is an option - but there is a limit and 80m will definitely not fit.

One option then is to use a quarterwave vertical. However this requires radials if you want the majority of your signal to be radiated above ground. I developed a quarter wave for 80m with four elevated radials and it works but is quite a hassle to set up. Working /P you don't always have room for four elevated radials.

Another option is to use the EFHW sloping. That is a good option and I have used it on numerous occasions. If the support is tall enough to allow for an angle around 45 degrees the antenna still has a low angle of radiation but also a lobe at a high angle. That makes it a versatile antenna. It has some directivity - in the direction of the slope. 
The challenge on 80m is that the EFHW sloping still requires a tall support for a reasonable (steep) sloping angle otherwise you will end up with only the high angle radiation. 

Inverted V antenna

Another option - using a single support - is to use an inverted V dipole antenna. For 80m I find it a convenient antenna to set up and it comes with a unidirectional radiation pattern (in the horizontal plane) that fits my needs when I am "being chased" with chasers from all directions.
The inverted V has a high angle of radiation. On my 18m pole it very much resembles a sloping half wave dipole of the same length. The main difference is that the sloping wire will have 6dB F/B ratio while the inverted V is omnidirectional. It is very much up to what you are looking for.

Practically when working on 60m or 80m (or 160m) - for more than a few QSOs - I choose the inverted V antenna. When my tallest support still was only 12m I also chose the inverted V as my default antenna for 40m.  

For my inverted V antennas I developed a universal center connector that fits on the fiberglass poles I use. It is a simple component made from 40mm PVC that allows me to connect various wires to a SO-239 connector. The reason I designed it with changeable wires is that it allows me to make different combinations like 40m and 80m inverted V's on one pole fed by one coax cable. 



The tie wraps on the sides are used to keep the cable tension away from the soldered cable shoes - otherwise the shoe will certainly break in due course. The hole through the center allows it to slip over the top segment of my fiberglass poles.

I developed a couple of these center connectors so I can set up different antennas at the same time. We use them for example with the YNOMY DX Group during the PACC contest when we set up three different inverted V's (40/80/160). We then have the 80m and 160m on the tallest mast together, being fed from one coax cable.

For each inverted V I have two separate dipole legs. Each dipole leg is cut to the right size and features a cable shoe as visible in the first picture. To hold the wire I have constructed a cable spool consisting of a piece of PVC (40mm) with two end caps. On each end caps I have glued a piece of wood and through the end caps and wood I have put a piece of threaded wire. 

40m wire spool (one leg)

This spool holds the antenna wire plus a long enough end of tension string. I find it works rather conveniently in that I can just stick the spool in the ground (slightly under an angle) where it unreels while I extend the mast. Once I am happy with the position of the mast and antenna I push the spool further into the ground, stopping it from turning. This way I do not need pegs or anything else to set up this antenna. 

Below you see an impression of the antenna with four legs - dipoles for 80m and 160m - ready to be deployed.

I just stick the spools in the ground in the direction I want the leg to go. Then I extend the fiberglass pole with the spools unreeling until the mast is fully extended. Then I pick up each spool and place it where I want the end point to be. The advantage of the spool unreeling is that there is only a slim chance the legs get entangled even when you have two dipoles on one mast - the wires are kept under some tension the whole time. 

A new addition to my portable antennas: 40m delta loop

Always looking for better antennas to use when portable, I stumbled upon the 40m delta loop. I had read about it a couple of times but mainly from expeditions using the delta loop on higher bands near to salt water. The results were very good but could not be reproduced on "regular ground". So I made a mental note to look into the antenna more later but without high expectations.

Then I came across an article by DJ0IP, who describes the delta loop on 40m as his favourite 40m DX antenna. Now that got my attention. Richard describes the loop and how to build it in detail. He opted for an antenna feed that makes this antenna vertically polarised with a low take off angle. 

The antenna does not need a lot of height to put up and looking at it from a /P operator, it is about as complex (or easy) to set up as an inverted V. So I decided I'd like to have one. I cut some DX wire to the right size for 1 wavelength on 7.1 Mhz. Then I created a 1/4 wavelength stub using 75 ohm RG-59. I never created a stub before but with the help of my miniVNA it was really easy to achieve the correct length.

Ready for transport: 40m delta loop with 1/4wl stub

This morning I had some time to try the antenna out in the field and tweak it to the correct length. So I went out to my favourite antenna testing field.

Delta loop in the field (lines indicate approx wire positions)

I used my 18m SpiderBeam pole and pushed the apex to about 14m. The center was about 4m high. By pulling both corners to the side I was able to create a triangular shape. Note that I attached the top of the loop to the third element of the pole. Attaching it higher I would pull the top too far down.

Checking the SWR I found I cut the loop too short - even though I had made it longer than the minimum length I calculated. So I added a bit of wire in the horizontal leg (as described by DJ0IP). I got the SWR dipping in the right part of the 40m band and still had a bit of time left to test it on the air.

WPX contest meant the band was filled with signals. Most of them were from the EU as I was nearing local lunch time. I did hear ZL4 peaking s7 outside the EU bandplan and I copied TI5 buried in QRM. So it did seem the loop was receiving signals. I tried TI5 (new one on this band) but I just could not copy him well enough through all the EU splatter. I also heard AJ4A in KY and he was able to copy me. Not a new DXCC but KY is the furthest I have worked into the US on 40m. So it seems the loop works both on RX and TX.
It needs a lot more testing to claim that it beats any of my other 40m antennas (inverted V, efhw, c-pole) but it starts out promising.

I did notice the antenna is very sensitive to height above ground (DJ0IP already warned me about that). So I added this feature to be able to tune the antenna quickly when using it again.

Copper wires added to the horizontal leg for easy tuning 

CQWW 2016 experiences

Logging a lot of new (band) ones on the low bands

As planned I went out this weekend to try and catch some new band DXCC - so not necessarily atno although I would have enjoyed that bonus.

My focus was on the low bands this time. I did take my hexbeam just in case there were new ones for me to catch on any of the higher bands. In retrospect it was not really worth the effort though. I logged one new DXCC on 20m and three on 15m. I learned I was too late as I could have worked more new ones on 15m but soon after I started (around 15h UTC) the band started to fade.

Apart from the hexbeam I took my recently constructed vertical that acts as end fed half wave on 40m and as a quarter wave on 80m with elevated radials. It turned out the end fed was resonant in part of the 160m band as well. I brought my tuner so I was able to use the whole band with that antenna.

An evening out on a deserted industrial area - hexbeam and vertical

Scanning the low bands

The low bands were noisy. The geomagnetic storm I experienced last Wednesday had settled a bit but it was still noisy. Another thing is that with a contest as big as CQWW the rather narrow bands are one big splatter party. This is especially true on 40m.

After spending time on 15m and 20m, logging only a handful of contacts, I turned to 40m around 15:30 UTC. There was not a lot to chase there, so I went down to 160m. It was early for that band but it was easy as I did not have to change anything when switching between 40m and 160m. For 80m I had to change the antenna setup slightly so it took some time to switch to and from that band.

Using my laptop with HRD Logbook I was able to monitor the cluster and see where I could find new ones. HRD shows you whether a DXCC that is spotted is already in your log for that band. Based on that information I switched between the bands. Unfortunately my laptop battery died at some point. I did bring an external battery but forgot the cable. I then relied on just listening around and on the cluster app on my phone. The downside is that I just cannot remember what DXCC I worked on what band.

Moving around across the bands I logged 69 contacts in 12 hours. Not particularly impressive during a contest (I suspect some stations managed more contacts in that period). However they contribute 44 new band DXCC to my collection.

Experiences per band

My 40m antenna was working as I expected. It is not a miracle antenna but I could work what I could copy. This included PY, a new one and the ODX on this band this weekend. I logged him when I had taken down the hexbeam and just wanted to check the low bands for the last time before taking down the vertical. I was happy with that catch. There is however a lot I cannot hear that others apparently can hear - judging from QSOs where I can only copy one side. This vertical end fed is clearly not a match for a beam. Conditions weren't particularly good and QRM was incredible, so I only logged 4 new DXCC on this band. I had hoped to log more new ones to move towards my 5th 100+ DXCC. I was counting on skip to the Caribbean but I only worked 8P.

My 80m antenna was better than I expected. The quarter wave relies on the ground system to work and with only 4 rather short elevated radials I was not expecting a lot. But again I could work almost everything I could hear. ODX this weekend was A6 at more than 5000km and I logged 12 new DXCC on this band. Note that I don't use this band at home and I had only logged 37 DXCC before (mainly on one evening and night in the snow when I joined the PACC for the first time).

On 160m I had only worked one station so far since I got my full license - some nearby german super contest station on CW on a shortened 40m wire antenna. This of course meant that almost all stations I heard were new DXCC on that band. The antenna was resonant but very short for this band (20m). I could work more than I expected but could not work everything I could hear. I noticed some stations had difficulty copying me while I could copy them without a problem. So there is still a lot to improve for this band. Starting with only 1 DXCC this was of course the best scoring band. I added a whopping 28 new DXCC here. ODX on this band was a respectable 2900km into 5B4.

Preparing low band verticals for CQWW

Conditions on HF have been better than they are the last few months. I find this a good reason to spend more time on the lower bands. 

Another good reason is that I completed my 100 DXCC on the fourth band just last week or so. It was on 17m. I am not counting on reaching that number on 12m any time soon - as I have failed to use that band when conditions were more favourable. So the next candidates are 40m and 80m. I could also go for 30m of course but phone remains my favourite mode.

With the limited space I have at home I will need to go out /P to work new DXCC on those bands. At home I use a shortened end fed wire for 40m (just 12m long) and that will not really bring me any further than I have reached so far. 80m is even more challenging. I have not worked out an effective solution for that band yet. The other obstacle is that the areas I need to work are generally workable late at night or very early in the morning. Using phone at these hours in a room that is not sound proof will get me into trouble with the rest of the family.

All of this made me decide to focus on the low bands during CQWW this month. A couple of times before I have used this contest to hunt DX by reserving a considerable (to my standards) amount of time during the contest weekend going out /P with the best antennas I have. In the past I have used a 4 element mono band yagi for 10m that created an unforgettable experience where I just worked atno's like there was no tomorrow and I have used my hexbeam with success as well.

On the low bands I used inverted V dipoles before. They work, and have provided me with new band DXCC but they have a (mainly) high angle radiation pattern. It would be nice to try something with a better DX profile. So that is why I went out today to test two verticals I prepared at home: a quarter wave with 4 elevated radials for 80m and an end fed half wave for 40m (this time full size instead of the shortened version I used before). 
To be able to switch them easily - without taking down the mast - I use the same radiator for most of the length. The 80m antenna is a bit longer so I have an extension wire I can add / remove that connects to an SO259 socket with the four radials. When I use the antenna on 40m I disconnect the last bit with the radials and add my end fed transformer.

18m pole holding a stretch of wire

Today was also a test to see if I could set up my 18m mast by myself in the field. Normally I use a support like my car or any sign post or fixed pole I can find. The contest location I use is just open field. After some trying I found a procedure that worked well.

I used my VNA and my radio to see if the antennas worked and they indeed seemed OK. There was no enough time to do serious testing on the air and the bands were in terrible shape (s8-9 qrn/qrm). The plots and TX tests showed me that the 80m antenna is easily usable from 3.6 to well over 3.8mc. It dips in the phone contest region of the band. The bandwidth of the 40m end fed was much wider than the trapped version I used before. I can use it across the whole band.
I also found that the radials of the 80m vertical really need to be off the ground some 10-15 centimeters. If they are too close to the ground the performance really deteriorates with SWR rising above 1:5 easily (1:1.4 when the radials are well off the ground).

It seems I am ready for some action this weekend. Now let's hope the earth magnetic field calms down in time. 

4,5 hours of antenna work

This morning I went out with PD7YY and PG8M to test our low band antenna set-up in preparation for the PACC contest in February.

It took us a lot of time to get the set-up right mainly because we were too ambitious in our attempt to support 3 different dipoles (inverted v style) from one center pole.

If you have 6 wires running from a rocking fiberglass pole with a couple of guy wires to add to the complexity, you will end up with a nice spaghetti.

So we will change our plan and support only 2 antennas from the center pole.

We did manage to tune our new full size 160m dipole and even worked on 10m with it...

More about this experience on the Ynomy blog: low bands preparations