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.

Test: End fed wire versus AlexLoop on 20m

Recently I did some tests with my two WSPRLite beacons. I started testing my AlexLoop against a 20m long end fed wire on 40m. The wire beat the loop quite dramatically.

One of the comments I got was that the loop should do relatively better on higher bands. That is why I ran a test on 20m as well. I collected the data about 2 weeks ago but due to other commitments I only got around to analysing it today. 

So what was the set-up? As in the previous article, I set up the AlexLoop in the garden with the center of the loop at about 2 meters high. The end fed wire this time was 10 meters long and ran from the back of my house into the garden sloping from about 7m high to about 2,5m high. I ran the beacons on 200mW for 2 consecutive days. 

The WSPR data shows:

• 514 spots from 49 spotters were received for the beacon on the wire 
• 436 spots from 29 spotters were received for the beacon on the loop 

This already gives you some impression about the difference. More stations were able to pick up the signal from the wire. 

Looking at the spot map below (distance in km vs SNR) you can see the orange profile of the wire is slightly shifted to the right (higher SNR) as compared to the blue profile of the loop. It is not as big a difference as on 40m though. 
More prominently you can see that the odx is again much higher for the wire as the signal was picked up across the pond in East Coast US (orange spots on the top).

This time the overlap is bigger, which makes it interesting to zoom in on a single spotter to see the actual signal strength over time. I selected one spotter that generated the most spots (EA8) but did check if the profile was any different at other spotters. This seems like a good sample for those stations that heard both. The orange line shows the SNR of the end fed wire, while the blue one shows the loop. On average (also looking at other spotters) the loop is 3 dB down across EU.

There are not enough spotters to make further assumptions about performance differences at specific distances or directions. What you can see is that for DX the signal from the wire is received within a 6dB range of SNR. The loop is not reaching the lowest end of that SNR. So it seems the wire is beating the loop everywhere but more so on DX.

Test: End fed wire versus AlexLoop on 40m

Recently I acquired two WSPRLite beacons. I want to use them to test various antennas to find out which ones are most effective /P. I have built a number of different antennas and I still have a few projects planned. Modelling antennas gives you an impression what to expect but you only find out in the field what the real performance is. Actually, you need (more or less) parallel reports to account for changing conditions and WSPR is a nice system to get these reports accurately. 

Two identical 200mW WSPR beacons

I started using the beacons at home testing the performance of my AlexLoop against my default antenna - an end fed wire. At home I use 20m of wire that is resonant on 10, 20 and 40m. That wire runs from the back of my house at approx 8m high to a corner of my garden and then still a couple of meters along the far end of the garden - sort of an L-shape. It ends at approx. 1.5m high. Nothing special - not your DX killer.

Although this is a convenient test for me to do at home, the comparison is not that exotic as both a low hanging and sloping end fed wire and a portable loop are realistic /P antenna options.

The first tests I used the AlexLoop in the attic on 20m, 30m and 40m. It turns out that although the loop is higher there, the attic itself attenuates the signal too much. It is just not picked up while I do get spots from the end fed wire. So I moved the loop to the garden at a height you would put it at when going /P - the center at about 2m high.

AlexLoop in the garden

I tuned the loop to 40m. Now spots were coming in for the AlexLoop. Running both beacons for 24h on 40m I can get a good picture of the difference between the AlexLoop and the (low) sloping end fed wire. 

Comparing the spots of the two antennas from the same RX stations, I find that the loop is mostly 10dB or more down from the end fed wire. That is an enormous difference. There is no advantage to be found on any distance for the loop.

Odx for the AlexLoop was EA8 with 3000km (2 spots from EA8) with 39 different spotters over the measurement period.
Odx for the end fed wire was N8 with 6500km (14 spots from W) with 110 different spotters over the measurement period.

The graph above shows the spots for the end fed wire (blue) and the AlexLoop (orange) on 40m over the same measurement period. The distance to the receiving station (in km) is on the vertical axis and the signal strength (in dB) reported by the receiving station on the horizontal axis. 

Apart from the two orange dots at 3000km (EA8) the AlexLoop does not reach much further than 1000km. You can also see that the end fed wire gets better signal reports - with significantly more dots to the right. 

So, my first test of the beacons worked out well and I have my first bit of data on two antennas. My idea is to create a separate section on this website dedicated to antenna performance based on future experiments with the beacons.