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"Mungo Bulge" wrote: Me is thinking "I'm vindicated" and Chucky is thinking "Another nut case". You're both right. So why does it work, simple. The antenna isn't a Marconi; it's an industry standard Marine HF band antenna, 2-30 MHz bandwidth, 10.8 MHz resonant frequency, 23 feet high and when connected to an HF radio set configured to its manufacturer's specifications it will perform admirably. If that were not the case, we would have had to have had at the very least five quarter wave Marconi antennae ranging in height from 7.8 to 117 feet and we don't. That Chucky is the proper use of reductio ad absurdum logic. Really close Mungo, but the antenna you are talking about doesn't really have 2-30Mhz Bandwidth, at all. It is a Marconi tuned by an Autotuner, to make it look like a 50 Ohm load to the radio so that the radio will transfer as much power as possible to the antenna, minus what is lost in RF Ground. If the RF Ground impedance is higher than the Antenna Impedance, with the autotuner doing it's best to make the whole system appear to the transmitter as 50 Ohms, then most of the RF Energy will dissipated in the RF Ground and lost to the communicator. Autotuners suck, when compared to any manual tuner, specifically due to the way the tuning software has to impliment changes in binary steps, and how the Phase Detector Sensors provide feedback to the processor while doing a tuneup. This all plays heavily into the design of the antenna system connected to the autotuner, as any good tech will put the "Untunable" 1/2 Lambda Frequency in a portion of the spectrum that the user will NEVER Need to use. There is a lot of practical considerations that MUST be considered when designing, and installing MF/HF Marine Radios on any vessel, but plastic and cellulose hulled vessels make all these things very much harder to compromise into an Effective Radio Installation. Me |
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