# Tag Info

1

There is a very simple answer regarding the diagram "Additional loss in dB caused by standing waves." It shows the fraction of the power sent into the cable that is converted to heat. (The rest is delivered to the antenna.) We could measure voltage, current and phase to compute power at both ends. There would be an additional loss if the ...

2

The question addresses a persistent confusion which is widespread especially in the ham radio community and can be tracked down to some published material (here no names!) and has survived since many years. However, a clarification can be straightforward and does not require complicated math. This answer starts from the “Total Feedline Loss” equation that ...

0

Yes, you can if the feeder length is right. It should be around 1/4 of the operating wavelength or any odd multitudes of 1/4 (i.e. 3/4, 5/4, and so on). For example, if the feeder length (measured from the feed point to the point where it touches the ground for the first time) is in the range of 0.2 - 0.3 wavelength, you can do quite OK without a current ...

2

This model makes two simplifying assumptions: losses are uniform throughout the transmission line, and there is a lossless tuner between the transmitter and the feedline adjusted such that the transmitter sees a matched load The first assumption isn't directly relevant to your question and is discussed in more details in the answer you linked. Now about ...

-5

The difference is that a (perfect) transmitter is trying to drive some (oscillating) current into or out of the feedline. Any reflected voltage coming back will bounce off a source trying to drive that junction to a different voltage, if it's out of phase. Or be amplified if it meets an in phase source. A receiver's passive impedance just eats the incoming ...

4

Let's say the antenna impedance on a given frequency is 100 Ohm, the feedline is lossless 50 Ohm, the transceiver input impedance is 50 Ohm. Between the antenna feed point and the feedline SWR = 2, 11% reflected power. This is a bit of dangerous thinking, because the distance between the antenna feedpoint and the feedline is zero. As such there can be no ...

2

I think you've answered your own question. In case a, with an antenna with 2:1 SWR and an otherwise lossless system, 11% of the power will be reflected and re-radiated by the antenna, so 89% makes it to the receiver. In case b, all of the power will be delivered to the receiver. Antennas are reciprocal, so all losses in transmit are the same as losses in ...

1

If the antenna isn't lossless (e.g. not superconducting), then some of the received RF energy reflected back into the antenna due a feedpoint mismatch will eventually be dissipated as heat in the antenna, or re-radiated as RF. But for received signals this is possibly only a loss of nanoWatts or picoWatts. However, not only is reflected signal energy ...

0

The cable between antenna and tuner is part of your antenna. Use oxygen-free copper wire (its a boat on salt water...). In case of a long wire connection between the feed point of your antenna and the tuner consider to place the tuner at the feed point of your antenna and use a coax cable between RX/TX and tuner. When you use only RX than forget every ...

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