RadioBanter - View Single Post - Relationship Between Antenna Efficiency and Received Signal Strength

Jerry Stuckle · January 24th 14, 03:45 AM posted to rec.radio.amateur.antenna

On 1/23/2014 9:42 PM, wrote:
On Thursday, January 23, 2014 8:21:27 PM UTC-6, Jerry Stuckle wrote:
On 1/23/2014 7:18 PM, wrote:

On Wednesday, January 22, 2014 4:32:31 PM UTC-6, Irv Finkleman wrote:

Q. Is there a relationship between the efficiency of an antenna and the

received signal strength?

Signal to noise ratio, very little. Received signal level vs

a more efficient antenna, can be quite a bit. But if the s/n

is appx the same, no biggie.. Lower level on the S meter, but

things should sound about the same when listening to it.

You forgot the noise generated by the receiver. With a weaker signal,

the S/N ration will be lower.

That would be an issue on VHF/UHF. We are talking HF here.
On HF, external noise picked up by the antenna is almost surely
going to greatly swamp any internal receiver noise.
Assuming a decent receiver anyway, and the one he has should
be fairly good.
That's one reason why I say if the background noise increases when
connecting the antenna, it should be good enough. If it doesn't,
there could be a problem.
But it will take a really dead antenna system to be like that on HF.
Even just sticking a 5 feet piece of wire into the center pin of a
decent receiver will cause the noise level to increase, and thus be
a fairly viable antenna. Not that it's going to pick up everything,
but it should pick up quite a bit. Note the portable SW radios
with short whips, etc..

It is also an issue on HF, especially with less expensive receivers.
You don't see it on the S-Meter because the meter is set such that the
typical receiver noise doesn't show up. But it is there. And it does
affect weak signal intelligibility.

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