[aprssig] Re: PHG Protocol Antenna Gain

[Stephen H. Smith]

John Langtry, VE3NEC wrote on 1/5/2005, 9:17 PM:

 > For one example, VE3YAP, we have a 4 bay Sinclare array -
 > 6.1 dBd at our site. I know for one dipole the difference
 > is about 2.25 dB between dBd and dBi; But what do you do
 > with an omni array ?

It's the same difference.  dBi is referenced to a theoretical 
omni-directional spherical radiator that is always 2.2 dB "worse" than 
the "0" db gain produced by a dipole.    Your Sinclair 4-dipole array 
would have 6.1 + 2.25 = 8.35 dBi gain.    [Note that dBi is often used 
by antenna manufacturers to create a bigger (i.e. more impressive) gain 
figure than comparing the same antenna to a dipole. ]


Furthermore, given

1)  A 2 dB difference in RF level is nearly undetectable.

2)  The PHG calculations are such a crude approximation of the actual 
real-world performance and coverage

the error introduced by using dBi vs dBd would be totally insignificant.