[TowerTalk] Fwd: Change in Frequency As Antenna Height

[Jim Thomson]

Date: Wed, 1 Jun 2016 16:47:03 -0700
From: Bob K6UJ <k6uj at pacbell.net>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Fwd: Change in Frequency As Antenna Height
Rises

You guys are way above my head :-)
I had no idea the resonant freq goes up and down as the antenna travels 
on its way up.

## it only goes up in freq, as height increases. 


I thought it just went up on a steep curve till about 15 feet then 
gradually after that.

##  That’s exactly what happens.   But beware,  20 ft above the ground doesn’t
mean 5 ft above a 15 ft high garage roof. 


I can see why some head scratching as we pass thru the "decrease zone"  
"what did I do now"  hihi

##  forget the  ....’decrease zone’...it doesn’t decrease. 
##  and the simple full size  dipole is not shifting 217 khz higher in freq....that’s pure fantasy.
##  ask anybody who has a motorized crankup, like the 89 ft  or  106 ft variety, how much the
resonant freq   of a rotary dipole, full size, or loaded, or 2/3 el yagi  ( this is all on 40m)
increases as tower is raised from min ...to max.   Ditto with a 80m loaded rotary dipole. 

Jim   VE7RF

73,
Bob
K6UJ