For some time now I’ve been using an Inverted-L style antenna, albeit not a perfect L but, I have found it to perform extremely well.
When I put the antenna up I was aiming for good NVIS radiation on 80/60/40m for chatting Inter-G and local EU stations <1000 miles from my QTH.
I wasn’t expecting good performance on the higher HF bands as the total length of wire is 37m which is somewhat long for the higher frequency bands however, I’ve found performance around Europe to be very good and extremely good over the north pole to Oceania and the USA.
As you can see from the antenna view above, it’s not a perfect inverted-L by any means however, its shape has actually proven to be advantageous.
Wire 1 is 9m tall, it then goes approximately 10.5m in length up to a peak of 12m above ground in the centre, this is where I have a 12m Spiderpole for support. From there the remaining 17.5m of wire slopes down to 5m above ground and is attached to the back of the house via a large insulator. Total wire length is 37m.
Wire 1 is at the bottom of a South facing garden and direction +X is north.
The antenna is tuned at the bottom of wire 1 using my CG3000 Remote Auto ATU at ground level. There are a number of random length radials hidden in the lawn and around the perimeter of the garden running mainly from South to North. I cannot run any radials to the south (-X) as this is farmland and not owned by me.
The radio I use is a Hermes Lite 2 SDR paired with a Xiegu XPA125B 100w amplifier. I normally only use 80w or less on all bands and so, my results are achievable using any 100w radio.
On the low bands I find it has great NVIS performance with excellent signal reports from all over the UK and out to around 1500 miles into Europe and beyond. This is exactly what I wanted from the antenna and I’ve been very pleased with it’s performance on 80/60/40m.
Looking at the 2D Far Field Plots on the 3 low bands the antenna has a typical NVIS high angle of radiation pattern with some gain.
On the 80m band maximum radiation is straight up, as expected with a gain of 6.08dBi (3.58dBd). The gain reduces at lower angles however, it still performs well out to around 1500 miles and occasionally even further.
Once again on the 60m band maximum radiation is pretty much straight up as expected however, I have worked in to Canada many times on 60m with excellent signal reports and so, it also has good DX capability too. With 5.26dBi (2.76dBd) gain it’s not a lossy antenna by any stretch of the imagination.
On the 40m band things start to change a little with the angle of maximum radiation being at 30 degrees rather than straight up. This gives the antenna “longer legs” on the 40m band making it very easy to work longer distances. It’s still very good for Inter-G but, performance over longer distances is considerably better. With a gain of 3.0dBi (0.5dBd) it’s performance is similar to that of a dipole at a similar height above ground.
Above 7Mhz things start to change considerably. The antenna becomes directional to the North West (NW) and North East (NE) giving excellent DX results over the North Pole into North America and Australia/New Zealand. The antenna does of course also have an element of high angle radiation making it useful into Europe and North Africa on the higher bands.
On the 20m band the maximum radiation is at 26 degrees with a gain of 5.68dBi (3.18dBd) pointing NW and NE. There is a lower gain lobe to the South West (SW) and South East (SE) giving excellent coverage through Europe and into Africa as can be seen in the 3D Far Field Plot and Azimuth Slice shown below.
Moving up in frequency to the 17m band the 3D Plot and Azimuth Slice are similar to that on the 20m band but, with a slightly lower angle of maximum radiation and slightly more gain as can been in the 2D elevation plot shown below.
With a gain of 6.61dbi (4.11dBd) at 22 degrees to the NW and NE and slightly lower gain and higher angle to the SW and SE the antenna has proven to work extremely well on the 17m band. My best DX on 17m so far has been a QSO with Eric, FK8GM in New Caledonia some 10230 miles from my QTH using just 80w of SSB.
The 15m band is a similar story, 7.6dBi (5.1dBd) at just 18 degrees pointing NW and NE. This antenna works extremely well into North America and Oceana (I’ve also worked FK8GM on 15m too). Once again there are lower gain lobes to the SW and SE at a similar angle along with some high angle radiation that aids coverage into Europe. The antenna really is a great all rounder on the 15m band.
The 12m and 10m bands are a similar story, low angle, high gain lobes to the NW and NE with lower gain coverage to the SW and SE.
On 12m the antenna has a very respectable gain of 7.66dBi (5.16dBd) at a low 16 degrees pointing NW and NE making it a great DX antenna. Once again, higher angle lower gain lobes to the SW and SE.
Finally on the 10m band the antenna has a gain of 6.96dBi (4.46dBd) at a very low angle of 14 degrees to the NW and NE. If DXing over the pole on the 10m band is your thing then this simple antenna will certainly help you along and maybe even put a smile on your face.
For such a simple antenna that will fit easily into many typical UK gardens I have been extremely pleased with it’s performance. Whether I’m gassing on the low bands with friends from the Matrix rooms or chasing DX on the higher bands, the antenna has put a smile on my face time and time again.
On receive the antenna is surprisingly quiet, with an S3-4 background noise on the 80/60/40m bands through to less than 1 S point of noise on the higher bands. Picking out the weak DX stations really isn’t a problem.
It just goes to show that you don’t need to spend a fortune on commercial antennas to work the world on the HF bands. With as little as 80w of SSB and a piece of wire connected to a remote ATU you can have just as much fun as the big boys!
More soon …