[TowerTalk] Dipole gain?

[Jim Thomson]

Date: Thu, 11 Dec 2014 09:05:28 +0000
From: Steve Hunt <steve at karinya.net>
To: Jim Thomson <jim.thom at telus.net>, towertalk at contesting.com
Subject: Re: [TowerTalk] Dipole gain?

The problem with using dBd is that a Yagi's advantage over a half-wave 
dipole (at the same height) can vary with height! So a dBd figure is 
only valid at one particular height, over one particular set of ground 
conditions.

Steve G3TXQ

On 11/12/2014 03:32, Jim Thomson wrote:
> Just rate the yagi, or any other ant in DBD. 

### Compare the yagi..in free space..to a dipole, also in free space.
Which is what 99% of the yagi makers are doing these days.
Then at least you can then compare any yagi....to any other yagi.
With both brands of yagis installed at the SAME height above ground, 
the difference in gain between em, should be the same as their free space 
gain differences.    

##  If folks wanted to do it right, then just graph gain in dbd..vs freq.
Ditto with FB vs freq, FR vs freq..and swr vs freq.   Unless a graph is 
produced, its all meaningless.   Sorta like your local car salesman quoting
HP at max rpm at redline.... but quoting max TQ  at a mid rpm. No point in 
cherry picking max gain-FB-FR. 

Jim  VE7RF