We have a double standard for reduced power output in an amplifier versus reduced radiation from an antenna system. However little or much we worry about a dB lost, can we value a dB gained or lost in the antenna system the same as in an amplifier? Let's look at how we regard amplifier losses.
0.3 dB loss, 100 of 1500 watts lost -- Most of us are disturbed by a new "1500 watt" amp only producing 1400. Even if they keep the amp, they may have a poor opinion of the amp and likely its manufacturer. So a 0.3 dB deficiency is at least irritating. At some threshold in the noise some will argue 0.3 dB can separate data mode decoding and not.
0.6 dB Loss, 200 of 1500 watts lost -- If it only produces 1300 watts, many will return the amp to its manufacturer.
1.0 dB LOSS, 300 of 1500 watts lost -- If our new 1500 watt amp only produces 1200 watts, we send it back. We replaced our venerable designed-for-1200-watts Alpha 76PA or SB221 by spending money on our new Smoke-Em QRO amp to get those 300 extra watts.
Will we now tolerate cancellation of our money spent on the amp by an avoidable 1 dB worth of collective losses somewhere in the antenna system? Arguably, 1.0 dB signal improvement in the noise can turn no QSO to QSO, improving Q's and mults in serious contest logs by working a better percentage of stations on those tough marginal paths.
2.0 dB *LOSS*, 550 of 1500 watts lost -- If our 1500 watt amplifier only produces 950 watts, the missing 550 means something in the amp is seriously broken. Perhaps one of two 3-500Z finals isn't lighting up. We won't operate an amp like that, and it's headed somewhere for repair or replacement.
5.0 dB !!! LOSS !!!, 1025 of 1500 watts lost -- If our 1500 watt amp can only put out 475 watts, the missing 1025 watts may mean it's been struck by lightning. It could have been totally corroded by years in a damp garage. It may have been plugged into 240V with the transformers connected and fused at 120V. It may have been run QSK on a too-slow-to-follow antenna relay, or run with an arcing unterminated SO239 somewhere, destroying components in the amplifier compartment with carbon arc traces and melted switch contacts.
Such an amp may be a disaster not even worth commercial repair. To help the club score, we might give away such an amp to someone who can repair it himself to upgrade his low power station to QRO for only the cost of materials he can't scrounge.
So why are we not equally irritated by loss in an amplifier and loss in an antenna system? Is it because sending the amp back to the manufacturer is obvious and a power meter is an understood and affordable measuring device, while accurate field intensity measurements are tricky, difficult, and usually involve expensive equipment?
In contrast, low band antenna system loss without SWR symptoms hides from us and confuses us, with muddled explanations and so-called solutions riddled with un-facts and urban myths.
5 to 7 dB, sometimes more, is a common Reverse Beacon Network (RBN) signal improvement replacing a poor counterpoise with an FCP.
Since the FCP's publication in May 2012, over 1000 individuals have opened telephone or private email antenna inquiries with us. Beyond a deficient counterpoise, more often investigations identified multiple sources of avoidable RF loss, a Pandora's box of RF issues further depressing performance, including ways not to install an FCP.
Replacing the original counterpoise with an FCP most often yielded the majority of eliminated loss, but was definitely NOT the ONLY source of loss.
Evaluating every aspect of antenna design, construction and environment, and cleaning up every last few tenths of a dB, often produced stunning improvements. In some "death by a thousand paper cuts" cases installers harvested over 10 dB of remedied loss, a few well over 10 dB, easily equaling an amplifier in increased TX signal strength.
We hope to help you diagnose low band RF losses and reduce all of them, to any degree possible, in your antenna project.
Given how commonly a station can reclaim that kind of loss, those who would rather run low power can possibly get an "amp" without breaking low power contest rules. Just harvest the loss. There is no rules penalty for improving antenna system efficiency.
And of course why not avoid these losses when an antenna is first erected?