A Guide to Optimal Antenna Matching
It’s a common and important question: "Do I need a tuner at the base of the antenna, or is my desktop tuner in the shack sufficient?" While many, if not most operators achieve great success with a shack-based tuner, understanding the engineering principles behind each method will empower you to build the most efficient station possible. Both work Real DX however, let's explore the two options.
The Engineering Ideal: The Remote Tuner
Placing an automatic tuner at the base of the antenna is the pinnacle of matching efficiency.
A remote tuner's job is to match the antenna directly at the feed point. This ensures that the entire coaxial feedline back to your radio maintains a near-perfect 1:1 SWR. With this setup, feedline loss becomes negligible, and maximum power is transferred from your radio to the antenna. This is the most robust and technically ideal configuration, popular with DXers, contesters, and Emcomm professionals who demand uncompromising performance.
Many modern remote tuners—especially popular 100W units—operate via "Power over Coax," requiring only a single feedline for both power and control. For high-power applications, 1500-3000W remote ATUs are also available, though some may require a separate 12V power supply at the installation site (or antenna base).
The Practical & Popular: The Desktop Tuner
A high-quality desktop tuner is a very popular and highly effective method for achieving a proper match. In fact, our customer polls show that at least half of Greyline operators utilize this proven setup. Some of these folks are RF Engineers too and we've had many deep-dive discussions with these folks too! As they are far smarter than most of us, we dug into it with them.
In this configuration, the tuner matches your radio to the entire system (coax and antenna), ensuring your transceiver sees a perfect 1:1 SWR. It's important to understand, however, that the SWR on the coaxial cable between the tuner and the antenna will remain high. With short runs of high-quality, low-loss coax, the additional power lost is often minimal and the difference in on-air performance is negligible. Thousands of operators work the world with this configuration. It will be important in this scenario to consider the proper feed-line options.
The Feed-Line makes the difference
The choice of feedline becomes particularly important when using a shack-based tuner. Because the coax must carry a high SWR, its potential for signal loss increases. While open-wire or "ladder line" offers the lowest possible loss - yes it's true - it is often impractical, especially in HOA communities.
Therefore, our recommendation is to invest in the highest quality, lowest-loss 50-ohm coaxial cable you can, such as LMR-400 or 600 (or bigger) or their equivalents. For most installations, especially those with shorter cable runs, this ensures that the vast majority of your power reaches the antenna, giving you the strongest possible signal on the air.
Our recommendation is two fold.
1.) Get the widest diameter coax you can afford, bury it and forget it knowing you did your best on feedline efficiency. Let the ATU do it's job.
2.) Learn about Antenna Physics: An Introduction, 2nd ed, which is available from the ARRL Store or your ARRL Dealer. Fascinating details that make up the antenna system.
3. If you completed #2 above at some level you may be strongly inspired to go the route of the RF engineer purist and use open wire line for your feeder. If so, reach out to us, it's a topic we find fascinating and there is worthwhile merit at the end of that road. Of course, 99.9% of us go with 1/2" coax and work the world and sleep great at night! (after DXing, of course!)
A Note on the Internal Rig Tuner (ATU)
It's worth noting on the automatic tuner built into most modern transceivers that it is a tool for fine-tuning, not heavy lifting. These tuners are designed to correct small SWR mismatches from an already near-resonant match. They are excellent for trimming a minimal SWR (typically 2:1 or less) that may be present after your primary external tuner has done its work. A non-resonant, all-band system like the Greyline VDA requires a more robust, wide-range external tuner to achieve its full efficiency. Using the rigs internal ATU is great for those little mismatches encountered along the way.
