[Elecraft] Driveway Distortion Demolition Derby

[Joe Subich, W4TV]

> Wes is quite right for the USA at least, and to make it easy 
> on us the FCC defines a 1/2 wave dipole as a "0 dBd" antenna 
> even though most 1/2 wave antennas show some gain over isotropic. 

Is that a dipole in free space or a dipole over ground?  

A dipole over ground will generally have a peak gain of 
8.3 to 8.5 dBi depending on the dipole mounting height and 
the angle (elevation) at which the measurement is made.  

Given the efficiency of a mobile whip, transmitter output 
power could probably be 500 watts before the ERP would 
be equivalent to 50 watts to a dipole with 8.5 dBi gain. 

73, 

   ... Joe, W4TV 
 



> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Ron 
> D'Eau Claire
> Sent: Wednesday, May 06, 2009 10:32 AM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] Driveway Distortion Demolition Derby
> 
> 
> Wes, N7WS wrote:
> 
> But the rule is 50 ERP, defined as 50 W into a 0 dBd antenna. 
>  A mobile whip has a lot lower gain than 0 dBd, in case 
> that's where you were headed.
> 
> -------------------------
> 
> Wes is quite right for the USA at least, and to make it easy 
> on us the FCC defines a 1/2 wave dipole as a "0 dBd" antenna 
> even though most 1/2 wave antennas show some gain over isotropic. 
> 
> It's up to the Amateur to document their antenna's gain if 
> not using a dipole. From 97.303(s):
> 
> "Licensees using other antennas must maintain in their 
> station records either manufacturer data on the antenna gain 
> or calculations of the antenna gain."
> 
> As Wes points out, that might allow using more than 50 watts 
> output into a small whip. It also requires running less than 
> 50 watts if using a gain antenna. 
> 
> Another difference between Hams and some other non-commercial 
> radio services is that traditionally most Hams take following 
> the rules quite seriously, whether or not any government 
> agency is watching us at the time. 
> 
> When one of our members doesn't, we take it upon ourselves to 
> point it out in the spirit of self-regulation. 
> 
> Ron AC7AC
> 
> 
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