[TowerTalk] wire yagis for the top band vs phased 26.5 m verticals

[Rik van Riel]

On 12/07/2010 10:31 PM, Chris Wagner wrote:

> Q: Who has experience with several verticals and huge wire yagis? Space
> permitting, I hope to compensate with more elements for lack of ideal hight.

Have you considered a bruce array?

You seem to be wanting low cost and a fixed direction, so a
two or three element bruce array may do the trick for you.

A two element bruce array contains a full wavelength of wire
and looks like this (use a fixed width font):

+-------------------------------------------------------+
|                                                       |
|                                                       |
|                                                       X
|                                                       |
|                                                       |
+----------------------    -----------------------------+

This is just two 1/2 wave dipoles folded over and connected
back to back.  The current in both vertical sections will be
in phase, giving you a decent amount of gain.

Half of one of these antennas is called a double L (or
lazy U).  You can string up a few and phase them in a fancy
way.

Having the vertical section about 60-70 ft tall is enough
to give decent performance.

The antenna is mostly independent from ground.  Rolling out
radials can give you an extra dB or two of performance, but
performance without radials is relatively close.

This beats something like an inverted L, where you can end
up being a few S points off with poor ground - not just a
few dB.

-- 
All rights reversed.