EFHW – Page 2 – M0AWS Amateur Radio

26 April 202226 April 2022

A little IC-705/AH-705 fun

I spent some time this morning in the garden with the Icom IC-705/AH-705 combo connected to my End Fed Half Wave (EFHW) vertical for the 30m band. This is a great antenna that works superbly on the 30m band. Being a resonant half wave fed via a 49:1 Unun it doesn’t require any ATU inline normally and so it’s quick and easy to use with any radio.

Today I decided to disconnect and remove the 49:1 Unun and hook up the Icom AH-705 instead. I thought it would be an interesting exercise to see how well it handled the EFHW vertical on both 30m and the other bands.

Icom AH-705 connected to the 30m Band EFHW Vertical Antenna

I purchased a couple of 5m leads for the AH-705 so that I could setup the radio on the picnic table in the garden and be a comfortable distance from the antenna. They worked great and allow me to use the radio in the spring/summer sun with ease.

Icom IC-705 setup on the picnic table in the garden

The little AH-705 remote auto ATU really does work well with the IC-705. Each time you change bands all you have to do is give a quick press of the PTT on the mic and it automagically goes into tune mode and matches the antenna to the 50 Ohm radio in seconds.

I was was really pleased to see that the AH-705 ATU matched the EFHW Vertical for 30m on the 80m, 60m, 40m, 30m and 20m bands with a perfect 1:1 SWR. With the antenna consisting of 14.81m of wire this makes it somewhat short of a 1/4 wave on the 80m band and I’m not too sure how well it will work. On the 40m band it is a 3/8 wave antenna so should work well. It’s a 1/4 wave on the 60m band and of course a half wave on 30m band as per it’s original design. On the 20m band it is just under 3/4 wavelength long so hopefully should work reasonably well. Of course it won’t be as good as my 20m band EFHW Vertical that has a much lower angle of radiation but, will make an interesting comparison.

The antenna also tunes up nicely on all the other higher bands including the WARC bands. On 17m it is getting close to a full wave length and on 15m it is just over a full wavelength and so should work fairly well on these two bands albeit with a higher than optimal angle of maximum radiation.

On the 12m band it is 1.25 wavelengths long and of course on the 10m band it is almost 1.5 wavelengths long. I’m not sure how well it is going to work on these two higher bands but, for a 14.81m long piece of wire it certainly gives me a good chance on a wide spectrum of frequencies.

30m Band EFHW Vertical Antenna in the breeze

The bands weren’t in particularly good shape this morning but, I found some SSB signals on the 20m band and so decided to see if I could make some contacts.

First contact was with S51DX in Slovenia. He was using 1kw into a 5 element beam pointed pretty much directly at me. The little IC-705 S meter took a pounding with him peaking +30db over S9 most of the time. I was really pleased to get a 5/9 report from him using just 5w from the IC-705 on the standard 7v battery. Of course his station was doing all the work but, it’s good to take advantage of these big stations when running QRP power levels.

Next I had a QSO with John, EA7JUR in Almeria Spain. But this time the battery on the IC-705 was pretty much exhausted and so I hooked it up to the 12v supply to get it charging whilst I was on air. This of course gave me the ability to increase my O/P power by 100% to a massive 10w!

I wasn’t so strong at John’s end, only getting 5/5 report at best whilst he was 5/5-5/9 with me with some QSB. John was using a mini beam antenna again pointed towards me so once again all the work was being done at his end. We had a good chat for a number of minutes until it was time for lunch.

Listening on the 40m band I did hear a very interesting station, KN6IPA/Aeronautical-Mobile. Justin, KN6IPA is part of the crew on a USAF KC135 air-to-air refuelling tanker that flies out of RAF Lakenheath in the U.K. He was transmitting from the aircraft whilst in flight over Germany. His signal was between 5/9 and 5/9+20dB on my vertical antenna and had a massive pileup of people calling him from all over Europe.

I did try calling him with my punchy 10w of power but, couldn’t compete with the huge pileup of very loud, powerful stations all incessantly calling. It was really interesting to just sit back and listen to Justin’s information. He was using 300w into a wire antenna that runs from the fuselage to the vertical stabiliser. Of course being so high up he had a massive advantage and could be heard for hundreds of miles with ease, hence every one and their dog was calling him.

Photo of the KC135 tanker that KN6IPA was transmitting from courtesy of his QRZ.COM page

If you look closely at the photo above of the KC135 that Justin is a crew member on you can just make out the wire antenna on the vertical stabiliser.

I have to admit that I would love to spend a few hours on the radio aboard the KC135 whilst it was flying around, just imagine the DX you could work!

More soon …

20 April 202225 April 2022

IC-705 and EFHW Vertical for 20m = DX

My IC-705 and AH-705 arrived today from ML&S, I wasted no time getting it hooked up to an antenna and started working my way through the manual getting to know the menu system.

After a few hours tinkering I piped up on 20m SSB and worked a couple of stations with ease using 10w. No problems getting through and to my surprise got a 5/9 report from both stations.

Later in the evening I decided to give it a go on 20m FT8 using just 5w O/P using the battery on the back of the radio that was now fully charged. It’s interesting to note that I didn’t need any drivers on my MacBook Pro to use the CAT and Audio via USB on the IC-705. It was simply plug and go. Much easier than it was with the FTDX10.

There was a fair amount of DX about on 20m including a few stations from Australia and Japan. I never managed to get a response back from either but, PSKReporter was showing that I was heard!

PSKReporter showing M0AWS being heard by BG7BDB

I also noticed that a station in China was hearing me too. BG7BDB in LinXiang City reported hearing me at -17dB. I quickly hunted around the waterfall and found him and gave a call.

To my amazement he came straight back to me and we exchanged SNR reports, 73 and he was in the log.

Looking at my WSJT-X log the distance to BG7BDB is 5467 Miles, at 5w O/P that equates to 0.91mW/Mile!

FT8 really is an impressive mode, it allows QRP stations to work the DX that just wouldn’t be possible on SSB. I have to say I’m really impressed with the Icom IC-705. The receiver and filtering isn’t as good as my Yaesu FTDX10 but, it’s an impressive little package. Portable operations with this radio is going to be a lot of fun!

More soon …

5 March 202210 March 2022

Will raising my vertical antenna make it work better?

A question I get asked regularly is:

“Why don’t you mount your 20m EFHW Vertical antenna higher up in the air?
It’ll work much better the higher you get it”.

I have over the years tried raising and lowering my vertical antennas for DXing and found that keeping the base of the antenna and feed point low has advantages over a raised installation. I’ll try and explain this using some 3D and 2D far field plots from the EzNEC antenna modelling software that I use.

Below are the 3D and 2D far field plots as I have it setup at the moment. The 49:1 Unun is at ground level with the base of the antenna also at ground level.

20m EFHW vertical fed at ground level 3D Plot

20m EFHW vertical fed at ground level 2D Plot

Forgetting about the dBi gain figures for the time being and just concentrating on the overall radiation pattern you can see that with the antenna fed at ground level it has a typical circular radiation pattern with a deep null in the centre and a very low angle of maximum radiation. This makes the antenna perfect for DXing and is backed up by the success I’ve had on the 20m band working Australia, Thailand, Indonesia, South America, West Coast USA and Canada. This is exactly what I wanted and I’m extremely happy with it’s performance. I must add that I’m not looking to work European stations with this antenna, I’m only looking for DX stations especially those with very weak signals.

So now let’s take a look at what happens to the radiation pattern when we raise the antenna and the feed point above ground level.

First let’s raise the antenna so that the base and feed point are 3m above ground level.

20m EFHW Vertical with base and feed point 3m above ground 3D Far Field Plot

20m EFHW Vertical with base and feed point 3m above ground 2D Far Field Plot

Looking at the two far field plots above you can see that with the antenna and feed point raised by 3m we start to get some high angle lobes appearing in the centre of the radiation pattern. The overall maximum radiation is still at a low angle and so this would still be good for DXing but, does have an element of high angle radiation to it now. This will of course mean we’ll start to be able to work stations much closer to us and also be able to hear them better.

Raising the base of the antenna and feed point to 5m above the ground we see that the high angle lobes get even bigger and start to distort the overall radiation pattern of the antenna.

20m EFHW Vertical with base and feed point 5m above ground 3D Far Field Plot

20m EFHW Vertical with base and feed point 5m above ground 2D Far Field Plot

At 5m above ground the two high angle lobes have increased considerably which will result in more high angle radiation from the antenna. Maximum radiation is still at a low level though and so DXing will still be good with this setup but, from experimentation and experience I know that there are times when closer stations start to affect the ability to pick out the weaker DX stations. This is exactly what I don’t want.

Raising the antenna up even further to 10m above ground we get the following result.

20m EFHW Vertical with base and feed point 10m above ground 3D Far Field Plot

20m EFHW Vertical with base and feed point 10m above ground 2D Far Field Plot

At 10m above the ground the two high angle lobes shown on the 2D elevation far field plot are now almost as big as the main lobe below it. This means there will be considerable high angle radiation from the antenna which will result in the ability to communicate with stations much closer to your QTH rather than focusing just on the DX stations.

If you’re looking for the best of both worlds then getting your antenna up higher is the way to go, you’ll be able to work stations in the 300-1500 miles range with ease and the DX stations thousands of miles away.

From my experience there is one disadvantage with this in that the closer stations tend to drown out the weaker DX stations reducing the overall DX capability of the antenna and this is why I keep the antenna feed point at ground level. From experimentation and experience gained over the years I’ve found that keeping the antenna base and feed point at ground level gives me a better chance at working the DX than I have if I raise the antenna up higher.

As with everything in life there’s always a compromise!

So it really does depend what you want to use your antenna for. If like me you only want to chase those rare DX stations that are always difficult to get then keep the base of the antenna and feed point low. This will maximise the null in the centre of the radiation pattern and keep interference from “local” stations to a minimum. The draw back to this of course is that you won’t be able to work the closer stations when there is no DX around.

However, if you want the ability to work more “local” stations and the stronger DX stations raise your antenna and feed point up to a more suitable level above ground so that you obtain more high angle radiation from your vertical antenna. Then when there’s no DX around you’ll still be able to chat with the more local stations.

I hope this helps all the people that read my blog understand the choice I have made and why I keep the base of the antenna and feed point at ground level.

More soon …

19 February 202219 February 2022

Falklands Calling …

When I lived in France (F5VKM) I was totally focused on the low bands. I spent years trying to get the Falkland Islands on 160m. Now living in the UK with a typical small garden I no longer have the luxury of big antennas. Currently I’ve just got my EFHW Vertical for 20m at the end of the garden.

Today I heard the Falkland Islands on 20m for the first time since setting up the new station, I was amazed to say the least.

I decided to give the two stations a call, didn’t get an answer from VP8ADR but, VP8VK then popped up and I snuck in and got a quick QSO with just 25w.

Working DX is so much easier on 20m than it is on 160m, I’m amazed!

-23dB is very close to the limit for FT8 but, it was enough to get a complete QSO and the Falklands in the log.

I also got VK6AS on 20m FT8 today, again with just 25w. This EFHW Vertical for 20m really is an excellent DX antenna, it’s perfect for the small garden too!

More soon …

10 February 202211 February 2022

20m EFHW Vertical sunset

4 February 202212 March 2022

20m EFHW Vertical + 49:1 Unun = DX

My 49:1 Unun arrived from UK Antennas today, lost no time getting it into the garden and connected to the 20m EFHW Vertical antenna.

I’m really pleased with the 49:1 Unun, really nicely put together and packaged professionally, great to get such a nice British made product!

Connecting the Unun up to the antenna I found that it added a little extra inductance I hadn’t planned for and so I needed to shorten the vertical wire a little to compensate.

It took 3 snips of wire to get the antenna resonant in the 20m band again, with an SWR of 1.3:1 and the sun starting to set I decided that was fine for now and I’ll fine tune it tomorrow in the daylight. (See end of article for update)

Heading into the shack the 20m band was buzzing, lots of big signals and DX. I switched on to the 10m band and checked the SWR there, 1:1 across most of the band, perfect!

I then went on to check the 15m band, now I wasn’t expecting a match as it shouldn’t resonate there but, I found a 2:1 SWR across the band, weird!

So back on 20m, I plugged in the MacBook Pro and started WSJT-X in FT8 mode to see what was around.

20m EFHW Vertical at the end of the garden

First contact was into Canada, VE2FVV with a -10 report both ways and 2962 miles, not bad for 20w.

I then worked a flurry of stations from the USA but, the one I was really pleased with was PP1WW in Brazil. 5610 Miles using just 20w, this EFHW vertical really does has a lovely low angle of radiation.

PP1WW was the last station worked as it was dark by this time and the band closed. It was interesting to watch the PSKReporter site to see where I was being heard.

As you can see from the PSKReporter screenshot above, I was heard pretty much all over the world. I saw a number of VK stations in Australia pop up on FT8 but, never managed to get an answer back from any of them even though they reported hearing me on the PSKReporter site.

I was also pleased with the number of stations that I heard, once again good global coverage.

Band conditions are generally poor at the moment and we’re in a bad part of the 11 year sunspot cycle. Hopefully in the coming years propagation will improve and we’ll be able to work the world on just a couple of milliwatts!

I also tuned up onto the 10m band and heard quite a few FT8 stations on there, I was surprised as I wasn’t expecting the band to be open.

So tomorrow, I need to fine tune the antenna for the 20m band and get the SWR down to 1:1, hopefully this won’t affect the 10m band tuning too much.

Once the 12m Spiderpoles are back in stock I’ll get one ordered and build the 40m EFHW Inverted L that I’ve designed, I’m hoping it will open up the 40m/20/15/10m bands for some DXing over the summer months.

UPDATE: I ended up snipping off a total of 34.5cm of wire to get the SWR 1:1 at 14.100Mhz. This makes the entire 20m band useable with the SWR less than 1.5:1 at each end of the band. 2nd contact after trimming the wire was VK2LAW at 10454 Miles using just 25w of power.

Information as to why it’s best to keep the feed point at ground level for this antenna is here.

More soon …

1 February 20225 August 2022

Going up in Frequency!

Ever since I got my Class A HAM Radio licence I’ve always been fascinated by the low bands.

160m, 80m and 40m have been my favourite go to bands for chasing DX for many years and I’ve really enjoyed overcoming the challenges that come with such low frequency radio operations. Working DX on 160m I learnt a lot, having a good receiver and a quiet antenna are far more important than having a lot of power. The QRM/QRN on top band often masks the weak DX signals and so designing and building antennas that have a relatively low angle of radiation but, are super quiet on receive is a skill that all top band DXers should embrace.

It’s particularly hard to work DX on 160m in the summer months however, all those DX signals are still there, they’re just masked by the static crashes that plague top band throughout the warmer months.

Discovering the grey line was a real eye opener too. Getting up early in the morning to catch that magic moment that starts just before the sun rises to about an hour afterwards, with DX signals pouring in from VK/ZL before the D layer gets established again. Discovering that on the grey line signals from afar often arrive from a very high angle and can be heard much better on a large horizontal loop near the ground than a large vertical.

As you can tell, I’m passionate about the low bands but, now I’m back in the U.K. and have a U.K. sized garden again those days of large full wave antennas on the low bands are gone and so I must look to pastures new.

To this end I’m going to get onto the higher frequency bands, 20m and upwards. I must admit that I’ve hardly used these bands as I’ve always been so focused on the lower bands.

Currently I have delta loop for 30m up in the garden, this is a great band for us CW and digital guys, it’s a band I really enjoy and so will continue to use it whilst discovering the higher bands.

So I thought I’d start with the 20m band, it’s a band that I’ve heard is really easy to work DX on. Being much quieter than the low bands I’ll give the delta loop antennas a rest and venture into the land of vertical antennas again.

Doing some antenna modelling on EzNEC the End Fed Half Wave (EFHW) antenna has a great radiation pattern with a nice low angle of radiation and even some gain compared to a dipole.

Construction will be easy as the antenna is so small compared to the low band antennas I’ve built in the past.

An EFHW antenna is a relatively simple affair and for 20m it’ll be somewhere around 10.25m tall depending on where on the band I resonate it.

The difficult thing about half wave or any multiple of half wave antenna is that they present a very high impedance at the feed point. Unlike a half wave dipole that is made up of two quarter wave legs that present an almost perfect match to 50 Ohm coax cable (or a 1:1 balun), the EFHW will have a much higher impedance, normally in the range of 2000 Ohms or more. Having such a high impedance also means high voltages at the ends, something to be very aware of especially if you have children or pets in the garden!

Matching to this type of antenna can be done two ways, a simple LC circuit for high impedance feed points or via a 49:1 Unun.

Since I’ve built 1:1 baluns in the past for my delta loop antennas I’ve decided to go the way of the 49:1 Unun.

Simple LC Circuit for High Z matching and a commercially manufactured LDG 49:1 Unun

Looking online for parts to build a 49:1 Unun I stumbled across UK Antennas, they seem to have a wide selection of pre-built EFHW solutions and some very nice looking 49:1 Ununs capable of handling 400w, much more than I will ever throw at it. Contacting Ian the owner of the company via Ebay I found he has a 49:1 Unun in stock that he can ship to me next day so I decided to go ahead and order one rather than source the parts and build it myself.

With the Unun sorted, let’s take a look at the radiation pattern for an EFHW Vertical on the 20m band.

Since I’m looking to do mainly CW and digital modes I’ll be tuning it for the lower end of the band.

Modelling this on EzNEC I’m pleasantly surprised at the radiation pattern of such a simple vertical.

To get a radiation pattern like this on the low bands requires a very large vertical, on 160m we’re talking 80m in height!

On 20m an EFHW is only around 10.25m long, very easy to put up in most U.K. sized gardens using nothing more than an extendable fibre glass pole. The 3D Field Plot shows the lovely deep null in the centre as you’d expect and a great low angle circular radiation pattern.

The elevation 2D field plot really shows the beauty of this antenna.

5.62dBi at 10 Deg and 5.56dBi at 5 Deg, perfect for the long haul DX chaser. The wide deep null in the centre will help attenuate the signals arriving at high angles from the EU that plague us on the East Coast of the UK.

So, it’s time to go find some wire, get cutting and get a fibre glass extendable pole mounted in the garden ready for the arrival of the 49:1 Unun.

More soon ….

UPDATES:

More info on antenna performance here.

Going QRP with the 20m EFHW Vertical and IC-705

Keeping it simple but effective – 20m EFHW Vertical