[Towertalk] LPA designs

[Phil Duff]

At 11:13 11/15/2002 -0800, Steve Katz wrote:
>I think the responsible manufacturers don't make any ridiculous claims about
>gain.  Tennadyne, for example, rates the T6 (12' boom, 6L 14-30 MHz) at
>5.1dBd and BW = 57 degrees, and it's very much bigger brother T12 (30' boom,
>12L 14-30 MHz) at 6.5 dBd and  on 20m.   Yet, the signals emanating from
>these antennas are frequently stronger than signals from similarly located
>stations using bigger stuff.  Why that is, is the question.

I find the numbers for the "efficiency" of the LPDA as compared to other 
beams to
be interesting.

Here's examples from the Tennadyne web site:

LPDA 99.2%

Mono-Band Cubical Quad 98.0%

Mono-Band Log-Cell Yagi 92.5%

3-Element Mono-Band Yagi 88.4%

4-Element Mono-Band Yagi 86.9%

Small 3-Element TrapTri-Band Yagi 30.0%

Is is not clear to me how these efficiency numbers are derived or what they 
mean in the real world but if true perhaps the touted LPDA efficiency might 
be responsible at least in part for noted stronger LPDA signals at times as 
noted by WB2WIK.

73 Phil NA4M




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Phil Duff NA4M     na4m@arrl.net   Georgetown, Texas