[Towertalk] 40M Dipoles (Was: Need EZNEC model 402CD..)

[Tom Rauch]

> Note that Bill's model shows a simple (full size) 40M Dipole
> at 1/2 WL (70 ft high) is 2.3 dB stronger than a 4 Square,
> providing further support to the notion that a 40M rotary
> dipole is a good, simple, and competitive antenna alternative.

In my experience models tend to fall in line more on 40 meters and up 
with real-world results, while on 160 results vary the most. Using a 
model to predict fractions of a dB, or even a couple dB, when system 
are close might not be wise. There are multiple reasons for using 
caution.

My main points are:

1.) Actual working results often vary from a model when the system is 
heavily dependent on things that models drastically short-cut, like 
earth characteristics. 

2.) On lower bands vertical tend to not be as bad in real-world 
performance as models might indicate.

3.) For receiving, gain is unimportant. The important parameter is 
directivity, which you can find by factoring loss out of the results. 
My web-page describes that.

Receiving performance should not be discounted when picking an 
antenna, especially on a trashy sky-wave band like 40.73, Tom W8JI
W8JI@contesting.com