Topband: Further discussions on EWEs

[James Rodenkirch]

thank you, Tom - great info!

> From: w8ji at w8ji.com
> To: rodenkirch_llc at msn.com; tshoppa at wmata.com; topband at contesting.com
> Date: Mon, 5 Nov 2012 12:37:34 -0500
> Subject: Re: Topband: Further discussions on EWEs
> 
> > Tom, et al: is there data that nail down the horizontal wire to vertical 
> > wire ratio?  I see in that write up by wa1on mention of 2.25:1 h to v 
> > but...is that some rule that can't be violated or.../
> >
> > For instance, assuming a vertical section height of 10' I could run a 
> > longer horizontal section but don't know if that gains me anything.
> 
> I can't imagine why there would be some set rule or guideline, except with 
> many qualifications. I'm sure there is some general range of lengths vs. 
> height for various configurations. The ideal shape would be rectangular with 
> source and load centered in the shorter vertical wires, which is the 
> equivalent of a base-fed  EWE over perfect ground.
> 
> The horizontal part or component of the antenna works best when it behaves 
> most like a transmission line with a velocity factor of unity (ideally 
> faster than light). The longer it is and the wider it is spaced, and the 
> poorer the earth below the antenna, the more the system responds to unwanted 
> signals in the horizontal mode.
> 
> The vertical component of the antenna wires acts like two verticals, and is 
> the desired signal response.
> 
> You can see the obvious conflicts. If the vertical section is taller, 
> horizontal spacing is wider and that response increases. If the length along 
> earth is longer, the verticals are separated more and this increases 
> sensitivity of the verticals (until they are 1/4 wave apart) but it also 
> makes undesired horizontal sensitivity increase.
> 
> There are a half dozen things that can make one thing better while making 
> other things worse. Everything, including characteristics of the earth and 
> things around the antenna, would interact.
> 
> If you really wanted to optimize an antenna like this, you would have to 
> make it two short verticals that are phased. After all, that is all the 
> antenna actually is.
> 
> 73 Tom 
> 
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