Antenna history

The journey from CP-6 to W-8010 via G5RV junior to a dipole

When I became a ham in 2006, my first antenna for HF was a CP-6 vertical antenna made by Diamond. This has been the only commercial antenna I have ever had for HF, all others got homebrewed.

Thanks to some good instructions from Thieu PA0M, in 2009 my CP-6 got replaced by a homebrew version of the Diamond W-8010. This antenna is resonant on 80, 40, 20, 15 and 10 meters. The building of this antenna was a great experience, and except for the very limited bandwidth on 80m this antenna has served me well. After a number of years some corrosion and UV light caused some issues and (just?) before it fell down I decided to replace it with another antenna.

On the internet I found a lot of information about the G5RV and it's smaller G5RV junior design. Given the limited space in my backyard, combined with the desire to build an antenna that was rather simpler than the W-8010 I decided for the 2 x 7.75 meter, ladderline fed G5RV junior antenna. The building of this antenna is documented on this website. This antenna has served for many years, given me reasonable results given the limited space, and urban noise levels. The only drawback is the lack of 80 meter band capabilities. During the winter time I would connect both legs together at the end of the ladderline, and use a separate ground wire to be able to get active on 80 meters, but it was never a great solution.

Sometime during the life of my G5RV junior, I was able to score an MFJ remote tuner, that I mounted at the base of the antenna in my backyard. As a result I could tune the antenne on all bands from 40 meter and have a reasonable SWR from the shack to the base of the antenna (minimizing coax losses and radiation from my coax).

When one of the legs of the G5RV came lose in 2019, I realised it might be time for another antenna homebrew project to get the slowly degrading G5RV junior replaced. As a result I started reading on the topic, and found a lot of good information on the website by Frits PA0FRI. My particular focus was to get an antenna that would also have some capabilities on 80 meters, while still serving the higher bands, considering the solar minimum situation around 2019.

A non resonant dipole

Given the available remote tuner at the base of the antenna, and some good experiences with different dipoles during field experiments where I typically connect the antenna to a tuner at the base of the antenna before it goes to any transceiver, I was not necessarily focussing on building an antenna with perfect SWR on all bands.

Studying different designs, and looking for similarities and information on why some designs work (or don't work), there was a lot of opinions, some well documented experiments, and very limited theoretical background for practical designs.

The idea of a non-resonant dipole, that has a size that doesn't cause too bad of an SWR on all common HAM bands has caused some HAMs to calculate what dipole sizes could work well for different sets of HAM bands (like 40-10 meters, or 80-10 meters, or even 160-10 meters). This line of thought, starts with all lengths of dipoles to be ok, followed by removing antenna lengths that would cause very hard to tune SWR values (like 2 x half-wavelength dipole). One of the results, also mentioned on PA0FRI's website, is the use of a 2 x 13.5 meter dipole. Such dipole would be tune-able on 80-10 meter bands. Given this antenna is less than half a wavelength for 80 meter, you could easily conclude it can't be good for 80 meter. That is correct! At the same the length is such that it just starts working as an antenna on 80m.

Given a 10 meter long backyard, it took some head-scratching to figure out how to fit a 2 x 13.5 meter antenna in. The 2 x 7.75m G5RV jr antenna, would just fit between the top of the house, and the backside of my yard. So I would have approximately and excess of 6 meters on each end to miraculously keep in the air. The solution for that was to zig-zag the end pieces on whatever space was available. While doing this I kept a statement from Harry PE2HD in mind to always put as much antenna copper in the air as you can.

The 2 x 13.5 meters dipole that I managed to get up in the air (thanks Rafael KM6ODD for helping me out!) is centerfed with a 7 meter open line (using spacers). As a result both legs of the antenna including the openline, could be made from 2 single pieces of antenna wire. Having no separate wires connected to each other will help connection/corrosion problems over time (I hope). Although experiments by others describe that for good tune-ability of the dipole the open feedline should be longer, that didn't work well in my case. As my antenna is only 7 meters up in the air, the feedline couldn't be much longer, considering the tuner is on the ground under the center feedpoint. Rolling up an openline, didn't give good results, so in the end I just cut it short to the length that would fit well. Contrary to what other experiments have found, my remote tuner is well able to match all weird and wonderful impedances on the 80-10 meter ham bands. The term Your Milage May Vary, applies.

After a few months of use, I can confirm I'm still happy with my bit of homebrew. Under the limited conditions in this solar minimum around 2019, I can still make some nice contacts on whatever bands are working for any particular moment in time, using SSB, CW and Weak Signal modes.

To wrap up this narrative, here's a picture taken of the antenna during the sunrise on 11 Jan 2020.