Further Evolution of My ‘Genetic Antenna’!

You may be aware that a genetic antenna is one produced by computer modelling and testing of multiple exotic versions and finally choosing the best option. Genetic antennas with specialized design have been successfully deployed for certain satellite operations where the design requirements were quite difficult to achieve by conventional antenna designs by humans. Being fed up with my loaded coil dipole antenna for 80/20m, short of a NanoVNA to find the exact frequency of resonance in the region of 80m band and thereby direction for trimming or extending, I took out the loading coils and the stubs and made it a simple antenna and checked various amateur radio bands. I found that it had an SWR of 5+ on 30m band, but was tunable using the built-in automatic antenna tuner of FT-710.

From the data on record I calculated that there was 642 cm wire to the East and 757 cm to the West, making a total 1399 cm, that is about 2600 cm short for an 80m dipole. Went out and bought 27m 1.5 sq mm wire and started working on zig-zag off center fed linear loaded inverted V dipole antenna for 80m without any loading coils. First I added the maximum possible length to the West where I have slightly more garden space, as three zig-zag lines to suit mounting points on the garden fence. Testing showed SWR around 3 on 30m band and around 4 on 12m band, both tunable with the automatic antenna tuner in the radio.

Next I added the remaining part of wire to the East, again in zig-zag fashion as three lines. SWR became 2.8-2.5 on 30m band, quite tunable range. There was no pick on Reverse Beacon Network for a CQ call at noon. All other bands showed HI SWR. Now I may be having slightly more than the required amount of wire for 80m. As linear loaded dipole with three layers is likely to have one third of the impedance of a regular dipole, I made the sides asymmetric to increase the feedpoint impedance as I do not have a matching transformer. But I have no means of measuring antenna impedance or point of resonance other than an SWR meter. Hence I will not be able to know if it is resonating beyond the amateur radio bands. It looks like I am trying to reinvent the wheel!