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

Brian Kirby kilodelta4foxmike at gmail.com
Fri Oct 8 23:36:36 EDT 2010


These were formulas I had written in my notes about 30 years ago, when I 
worked in Satcom for the military and NASA.

I think they used an efficiency of 55 percent

another was 20log D(feet) + 20log F(mhz) - 52.4 = dbi

and the main formula of gain in db = k(pi*D/wave)squared ....showing 
k=0.55, d is diameter, wave is the operating frequency

On 10/8/2010 9:47 PM, jimlux wrote:
> Brian Kirby wrote:
>> 20 log(base10) (diameter in meters) + 20log(frequency in ghz) +17.8 = dbi
>>
>
> That assumes some nominal efficiency?
>
> I'll have to remember that one.. 17.8
>
> It's like the 32.44 dB for free space loss between isotropes 1 km apart
> at 1 MHz
> (+20log10(dist in km) + 20log10(freq in MHz))
>
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