[600MRG] Relative outside noise...

[Tom W8JI]

The change in noise level between a load and a random undefined gain 
antenna is pretty much meaningless. Without knowing the antenna 
sensitivity any comparison to a dummy load is meaningless, at least 
beyond telling you you are limiting on the receive antenna system noise 
floor.

If you are away from power lines and noise generating devices and also 
using a low directivity pattern antenna, common mode reduction is 
meaningless. You do have to keep in mind antenna work by wavelengths, 
not feet or meters. Even with a very small antenna the near field 
extends around a half wavelength or more. Larger antennas of course can 
have a much more extended near field since they do not originate the 
local fields from a very small point in space.

630M has a much higher background noise floor no matter where we are at. 
That is why we get away with very tiny wavelength-size antennas and 
still limit on ambient external noise.

On 630M, not only are we closer in wavelengths to noise sources for a 
given distance, the noise-soup is thicker.

73 Tom



On 7/24/2023 8:36 AM, Dave Riley via 600MRG wrote:
> When it comes to 630m there seems to be more atmospheric noise than on 
> the upper bands. What is a nominal amount??
>
> After getting away from the AC line noise there still seems to be 
> about  8-12 db difference between antenna connected vs. a 50 ohm load 
> to the receiver..
>
> What are your thoughts on this broad band noise??
>
> Also I use KW twin lead laid upon the ground from the antenna in the 
> woods to the R75 with isolation toroid at each end..
>
> Is this the bottom of the quest for noise reduction??  Enjoying your 
> thoughts..
>
> 73s de Dave @ W1FRV
>
>
>
>
>
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