[TowerTalk] Change in Frequency As Antenna Height Rises

[jimlux]

On 6/1/16 7:10 AM, Jim Thomson wrote:
> Date: Tue, 31 May 2016 17:37:52 -0700
> From: Grant Saviers <grants2 at pacbell.net>
> To: Jeff DePolo <jd0 at broadsci.com>, towertalk at contesting.com
> Subject: Re: [TowerTalk] Change in Frequency As Antenna Height Rises
>
> A little sloppy, I should have said "transforms to some other SWR on an
> SWR bridge".
>
> We agree there are a couple of much better measurement means.  Your
> "lacking that" example still requires a measuring device that can do TDR
> and complex impedance measurements which a classic "SWR Bridge" can't do.
>
> It still seems a bit bizarre to me to be tuning individual elements of a
> beam near the ground with an SWR bridge. Also, several classic
> "great/proven" beam designs have been redesigned with good modeling for
> much better performance out of the same pile of aluminum.  And some well
> known brands showed zero gain in the K7LXC et al yagi tests raising big
> questions about "manufacturer's data.".  It's gonna be hard to convince
> me that there is a better way than good modeling to design a beam.
>

I agree that I'd trust the model more than measurements, particulalry 
close to the ground.

One might use previously measured data for "close to the ground" to 
allow a person to verify that the thing was assembled properly.