We have a double standard for reduced power output in an amp versus loss in an antenna system. However little or much we worry about a dB lost, let's get to a level playing field where we value a dB gained or lost in the antenna system the same as we value it 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 separates 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 spending money by 1 dB loss somewhere in the antenna system? Arguably, 1.0 dB 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 amp 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 run 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 an amp for only the cost of materials.
So why are we not equally irritated by loss in an amp and loss in an antenna system? Why not equal opportunity irritation? Perhaps it's because sending the amp back to the manufacturer is obvious and the wattmeter is a well-understood and affordable measuring device. In contrast, antenna system loss without SWR symptoms hides and comes to us confusing and muddled, so-called solutions riddled with un-facts and urban myths.
5 to 7 dB, often more, sometimes a lot more, is a common Reverse Beacon Network (RBN) signal improvement following an FCP project also addressing multiple loss issues.
Since the FCP's publication in May 2012, through 2016, over 250 individuals opened telephone or private email antenna consultations with us. Most investigations identified and remedied multiple sources of avoidable RF loss leading to poor performance. Replacing the original counterpoise with an FCP most often yielded the majority of eliminated loss, but was hardly the only culprit.
These FCP consults exposed a Pandora's box of RF loss issues beyond poor counterpoise, including ways not to install an FCP. Evaluating every aspect of antenna design and construction, with an eye to cleaning up every last few tenths of a dB, produced some stunning improvements. Some "death by a thousand paper cuts" projects yielded over 10 dB of remedied loss, a few well over 10 dB, easily equaling an amplifier in increased TX signal strength.
Given how commonly a station can have that kind of loss to reclaim, those who would rather run low power can possibly get their "amp" without breaking low power contest rules. Just harvest the loss. There is no rules penalty for improving antenna efficiency.
We hope to help you diagnose low band RF losses and reduce all of them, to any degree possible, in your antenna project.
And of course why not avoid all these losses we can when an antenna is first erected?