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Re: [TowerTalk] [Bulk] Change in Frequency with Height above Ground

To: towertalk@contesting.com
Subject: Re: [TowerTalk] [Bulk] Change in Frequency with Height above Ground
From: "Roger (K8RI) on TT" <K8RI-on-TowerTalk@tm.net>
Date: Fri, 27 May 2016 16:10:44 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I find that is another one of those, "In general", or "It all depends"  <:-)
I have an Aim that is sensitive enough to show feed point changes in Z due to the wind blowing trees? Antennas? Feed lines? Combinations? You can watch the parameters changing with the wind and even seasons, but I am talking about the 2nd or 3rd decimal place. Changes so minute the you, the rig, or the receiving station will never notice.

These are every day occurrences compared to changing height, or a metal boom of variable length on a boom truck, or crane. It would be interesting to watch all the parameters change as the antenna is raised and then the boom truck, or crane retreats.

73

Roger (K8RI)



On 5/26/2016 Thursday 11:41 PM, Grant Saviers wrote:
I thought and found in several cases it was up in F with up in height until last week when an A4S being tuned to CW for FD went the other way. Perhaps the equipment hoisting the antenna (a boom lift) had substantial interaction with the beam. A while ago with another antenna we did find significant interaction with a tram wire support.

Grant KZ1W

On 5/26/2016 20:24 PM, Don W7WLL wrote:
Brain dead. Manuals all in storage.

Lowering the height of an antenna above ground, such as a beam, will cause the resonant freq to decrease, increase?

Don W7WLL
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73

Roger (K8RI)


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