A 1.5:1 SWR = ~14 dB return loss.
On 6/5/2020 6:42 PM, Tom Holmes wrote:
Dana... I think that you are neglecting two important mitigating factors. 1. the cable loss at 1575MHz, even for a 25' run of RG-6, reduces those reflections quite a lot from one end to the other. It amounts to 2 - 3 dB in 25', depending on cable quality. 2. a 1.5:1 SWR is not a very big reflection to begin with, on the order of 20% of the incident power, about 7 dB. I am rounding a lot here just to keep the math easy...for me. By the time a reflection has made the round trip from the receiver back to the antenna and them back to the receiver, which is how the delay would have to manifest itself, it will be down at least 15 dB from its original self, and probably more. Given the coding of GPS signals which allows several satellites to share a common frequency band, that is not going to be much of a problem. And if only one end of the path actually is 75 ohms, then there won't be a delayed signal. Tom Holmes, N8ZM
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