[600MRG] ERP, EIRP, How & Why

[Kenneth G. Gordon]

On 28 Jan 2015 at 8:18, Edward R Cole wrote:

> Pat,
> 
> Sounds right to me.  I determined R+jX from a model in 
> EZNec.   R=0.83 and measured R with my modified MFJ analyzer as 
> 18-ohms.  Po=100w resulted in TPR= 4.61w  EZNec indicated gain

Gain? How can your antenna have any real "gain"? It is much too short to 
have any real gain. Please explain.

Even my 55' vertical has a "gain" of approximately MINUS 2 dB on HF when 
tuned to resonance.

> of 
> 1.48 (1.7 dBi) giving EIRP=1.48*4.61 =  6.8w.  ERP = EIRP/1.64 = 4.15w.
> 
> Only variance with Rudy's calculation is he adds 3-dB gain for dipole 
> over perfect ground.
> 
> My antenna is base loaded inverted-L: 43x122 feet.

For a total length of 165 feet. Wavelength at 472 KHz is about 2081 feet. 
Your antenna is about 8% of that.

I suggest that your actual ERP is much LESS than you have calculated. I do 
not see how it can be otherwise.

Ken W7EKB