[time-nuts] GPS backup for the stationary time and frequencyuser

[jimlux]

Magnus Danielson wrote:
> On 10/08/2010 08:22 PM, jimlux wrote:
>> B

>> You might do just as well with a flat cookie sheet.
> 
> Well, a 1 m dish gives you 48 dB gain at L1 if I calculate correctly. 

I don't think so..48dBi would be huge...A numerical gain of 48 I can 
believe:

  let's say we have an antenna that is 2x3 wavelengths (40x60cm, 1.5 GHz 
= 20 cm) or 6 square wavelengths. the gain is 4 pi * A, or about 75. 
But in reality, the efficiency is typically no better than 50% (because 
of sidelobes, illumination, etc.)... Call 66% to be sporty, and you've 
got a numerical gain of 50, or 17dBi.




> The normal antenna is at 6 db of antenna gain?
> 
> Even if less than perfect, not too big size is needed to get meaningful 
> antenna gain.
> 
> Cheers,
> M