[Towertalk] LPA designs

[Jon Ogden]

I'm really curious about those numbers.  A Cubical quad theoretically should
be no different than a Yagi.  The Force 12 web page has a good discussion on
that.

As for what the numbers mean, who knows?  I'd imagine that Yagi efficiency
changes as factors such as number of elements, boom length, element spacing,
etc. changes.  

When comparing an HF yagi dimensionally to a VHF or UHF yagi, you can see
how much of a compromise design even a big monobander is.

73,

Jon
NA9D

on 11/15/02 2:59 PM, Phil Duff at na4m@arrl.net wrote:

> 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.

-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)

Citizen of the People's Democratic Republik of Illinois

Life Member: ARRL, NRA
Member:  AMSAT, DXCC

http://www.qsl.net/na9d

"A life lived in fear is a life half lived."