If
you’re an active ham or contest operator you’re frequently
scanning the bands for best ionospheric propagation and a signal rich
environment. Whether rag chewing or contesting this means spanning
the HF radio spectrum from 1.8 to 54 MHz. Add VHF, UHF frequencies
and antenna farms can become a real challenge. Antennas are usually
specified over a frequency range with SWR plotted on a chart.
Usually with the antenna trimmed for a specific frequency the SWR is
flat (1:1) and remains tolerable to the transmitter (below 2:1) over
the CW or phone band. This operable window becomes narrower at lower
frequencies. Today's automatic antenna tuners are gaining popularity, providing a wider spectral performance window for antennas.
Always resonant antenna designs are optimal for RF propagation prompting the popularity of antennas such as the Step-IR (for fixed stations) and the Tar Heel or Diamond series (for mobile operation). These antennas provide active remote tuning of the physical antenna. That is to say the length of the resonating elements can be physically adjusted by remotely activated servo motors. Best resonance and SWR can be achieved at all times. Some of these systems auto adjust by tracking the VFOs frequency or a memory plot.
Many years ago I acquired a large variable inductor and capacitor to construct a home brew antenna tuner. It worked but it was difficult to adjust with changes in frequency. More recently I acquired an MFJ-998 auto tuner rated at 1.5 kw. It tunes antennas by rapidly relay switching networked inductors and capacitors to null reactance and optimize SWR. On a 43 foot long wire I can run my linear amplifier at full legal power on most bands. Connected to my Icom transceiver it auto tunes as it tracks the VFO. Living in a condo with limited space an automatic antenna tuner is most convenient. In my mobile I have an LDG auto tuner coupled to a Tar Heel HF antenna. I resonate the Tar Heel mid band and use the LDG to trim the SWR on the fly. This is great for contesting while minimizing operator distraction.
Recently in LinkedIn’s RF and Microwave and Circuit Theory and Analog Electronics groups, Frédéric Broydé, F5OYE and Evelyne Clavelier, F1PHQ posted their paper “A Typology of Antenna Tuner Control Schemes, for One or More Antennas” © 2020 by Excem. The paper is free to download. [1]
After reading the article I had great appreciation for the theory and implementation of antenna tuners. Spanning 24 pages I was surprised at the breadth and depth of their paper. As RF communication techniques proliferate, MIMO and multi-antenna configurations are of great interest in the commercial and amateur radio space. As amateur radio operators we might extract some valuable knowledge from their experience. It’s interesting that Frédéric uses a manual tuner on his amateur antenna (a dipole). Congratulations to Evelyne and Frédéric on their great work.
From an amateur radio perspective there are many antenna tuners available for amateur use. In case you missed the Hamcation hamfest in Orlando you can peruse a recent
Google search on antenna tuners here:
[2] https://www.google.com/search?q=antenna+tuners&oq=antenna+tuners&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCTU4MDZqMGoxNagCALACAA&sourceid=chrome&ie=UTF-8
Although I was tempted, I confess I didn’t purchase anything at Hamcation. Hopefully you brought home a few new toys. Wishing you good tuning for DX. Until next time be safe everyone.
Thomas D. Jay, W4TDJ
Corporate, private entities or publications referenced or linked in this article are the respective owners of their logos, trademarks, service marks, media content and intellectual property. Unless otherwise disclosed, Thomas D. Jay has no financial interest in companies referenced in blog articles or other published media communications. Thomas D. Jay is not a registered financial advisor. No representation is made to either buy or sell securities. Opinions expressed by Thomas D. Jay are his own. Thomas D. Jay does not employ or otherwise utilize/authorize third party agents to express his opinions, represent his interests or conduct business on his behalf except where formally contractually designated. Thomas D. Jay opts out of requests to share personal information or unidentifiable user data. Thomas D. Jay does not agree to indemnify or hold harmless vendors, clients or third parties to related contractual agreements and reserves the right to applicable legal remedies in lieu of arbitration. Thomas D. Jay retains all copyright and moral rights to his published material, content and brand marketing, and shall in no case be represented, depicted or characterized by parties/entities other than his published "About Thomas D. Jay" descriptor. Contractual agreements are to be written and interpreted in the English language and are subject to the laws of the United States. These terms and conditions shall supersede any conflicting agreement. Clients, vendors and concerned parties should check my blog site at www.thomasdalejay.blogspot.com for periodic updates or changes to theses terms.
Although I was tempted, I confess I didn’t purchase anything at Hamcation. Hopefully you brought home a few new toys. Wishing you good tuning for DX. Until next time be safe everyone.
Best regards,
Thomas D. Jay, W4TDJ
Corporate, private entities or publications referenced or linked in this article are the respective owners of their logos, trademarks, service marks, media content and intellectual property. Unless otherwise disclosed, Thomas D. Jay has no financial interest in companies referenced in blog articles or other published media communications. Thomas D. Jay is not a registered financial advisor. No representation is made to either buy or sell securities. Opinions expressed by Thomas D. Jay are his own. Thomas D. Jay does not employ or otherwise utilize/authorize third party agents to express his opinions, represent his interests or conduct business on his behalf except where formally contractually designated. Thomas D. Jay opts out of requests to share personal information or unidentifiable user data. Thomas D. Jay does not agree to indemnify or hold harmless vendors, clients or third parties to related contractual agreements and reserves the right to applicable legal remedies in lieu of arbitration. Thomas D. Jay retains all copyright and moral rights to his published material, content and brand marketing, and shall in no case be represented, depicted or characterized by parties/entities other than his published "About Thomas D. Jay" descriptor. Contractual agreements are to be written and interpreted in the English language and are subject to the laws of the United States. These terms and conditions shall supersede any conflicting agreement. Clients, vendors and concerned parties should check my blog site at www.thomasdalejay.blogspot.com for periodic updates or changes to theses terms.
References and acknowledgements:
[1] Frédéric Broydé, F5OYE and Evelyne Clavelier, F1PHQ “A Typology of Antenna Tuner Control Schemes, for One or More Antennas”
© 2020 by Excem. Open access license: you may reproduce, store and distribute this document, provided the document remains complete and unmodified. All other rights reserved.
[2] Google Search
