Last month, I was given the opportunity to participate in a 30-day test and review of the Bilal Isotron 40M antenna for the 100 Watts and a Wire podcast. The Isotron is a strange looking and compact antenna that has reviews with an overall rating of 4 stars on eham.net. After building and then testing the antenna for a month, I was invited to participate in the podcast along with two other hams to give our review of the antenna for the following criteria:
You can listen to the podcast here. In addition to the audio podcast, there are videos covering each of the review criteria on the 100 Watts and a Wire YouTube channel. (Each of the criteria listed above includes a link to the YouTube video for that topic.)
Assembling the Antenna
The antenna arrived in a sturdy box, and all of the parts were in good shape. The paper manual is adequate and includes diagrams that were helpful for assembly. It took me about an hour to put it together. Once assembled and tightened, it is a sturdy antenna. It’s worth reading the manual closely before attempting assembly, and again afterwards to understand the instructions for tuning the SWR.
Installing and Testing the Antenna
I installed the antenna on 28-foot heavy duty fiberglass telescoping mast from Max Gain Systems. The mast is located next to a long chain link fence, which may have interacted with the antenna and made tuning it a bit challenging initially. Once attached to the mast, I used a Comet antenna analyzer, and attempted to tune the antenna for the lower end of 40 meters for CW and digital modes. For my first test, with the antenna mast lowered, the SWR was just above 3:1. I believe that was partially due to close proximity of the metal fence. Also, the manual specifies that the antenna works best with a metal mast, likely to serve as a counterpoise. I attached about 25 feet of copper wire to the antenna ground as a counterpoise, and made some more tuning adjustments. After that, and when I raised the antenna to 25 feet, the SWR was down to 1.6:1. Close enough, since I have an antenna tuner in the shack.
Performance
I tested the antenna for 30 days using FT8, WSPR, CW and SSB. The first contact I made on FT8 was in Washington State… a very promising start! Using FT8, I was easily able to work stations all over North America, as well as some DX stations in Europe, Australia and Japan. I also tested the antenna using WSPR for 24 hours, and my signals were received across North America and in Europe. I used the antenna for all of my 40 meter phone and CW contacts during Winter Field Day, and I was able to make a lot of contacts across the U.S. and Canada. The antenna performs better than I expected it would. However, it is not a good for receiving when compared against my end-fed halfwave antenna. I made comparisons several days, and the wire antenna was always noticeably better for receiving.
Final Thoughts
Pros:
1. It actually works! When I first looked at the antenna, I was skeptical. After testing it for 30 days, I realize there are some use cases where this antenna is a good choice.
2. This antenna would probably good for someone with HOA restrictions, as it is small enough to be hidden. However, keep in mind that my testing was with the antenna mounted at 25 feet and in the clear.
3. Because the antenna is compact and can be raised quickly, it would also be a good choice for portable operations or emergency communications.
Cons:
1. The antenna is only for the 40 meter band. If you have space for several antennas, that’s probably not an issue.
2. The antenna can be somewhat finicky with SWR. It made several trips up and down a ladder, and lowered the mast a few times, to get it adjusted. I also had to retune the antenna after one particularly cold, windy, rainy day.
The antenna retails for $160. Would I have bought this antenna on my own? Probably not. During the podcast, each reviewer was asked to give a “signal report” between 55 and 59 as an overall rating of the antenna. My report was solidly in the middle with a 57. It is definitely strange looking, but the appearance and compact size belie an antenna that actually performs fairly well, as long as you don’t expect miracles. I will most likely take the antenna down from the mast to install an off-center-fed dipole, and see if one of my ham friends living in a HOA community would like to give the Isotron a try.
This was a great ham radio experience for me. I had a lot of fun building, testing and using the antenna. I also enjoyed being included on the 100 Watts and a Wire podcast, and Christian Cudnick, K0STH, is a great host.