Having a small postage stamp sized garden presents me with a problem for HF antennas, I have been using an Inverted Vee cut for 20m and when on 30m, I use an auto atu. I presently use a 6m fibreglass telescopic pole for erecting my 20m inverted vee so why not try a longer pole, for the test, I used a 8m pole with an 9:1 UNUN attached a 7.4m length of 1.5mm coated wire. The ‘antenna’ was approx 10ft from the building.
The pole is actually 9m long but I never used the last metre , I will run a test with the additional 1m added in the future.
A length of coax was attached to the UNUN and the transceiver, I ran a SWR check using 5 watts and finally, 15 watts.
Results are as follows..
160m – SWR high
80m – as above
60m – still to checked on 5 watts
40m – 1.3 (15w)
30m – 2.5 (15w)
20m – 1.3 (15w)
17m – 2.5 (15w)
15m – SWR high
12m – 2.1 (15w)
10m – 1.1 (15w)
6m – 1.3 (15w)
Using an auto atu, 30m, 17m and 12m matched in with no problems.
I gave out a few CQs on the 20m psk frequency and worked a RZ9 from approx 5,400kms away with a LY Latvian contact soon after, it was time to break down the antenna.
If you look at the photo, I used the same method I use to secure the 6m pole but as the 9m pole is larger, I will have to fix a post in the garden plus this will make erecting both antennas much easier and quicker.
Hopefully I’ll do some further work during the spring and summer months, I’ll take the setup into the local hills and try it portable with the FT 817…when and if this weather improves….