[Antennaware] Short Term Fix - - Verticals

[Terry Conboy]

At 09:23 AM 2008-03-07, W7WY warrenwolff at aol.com wrote:
>I recently moved to Lake Havasu City AZ and was in hopes of a GIANT tower with
>OptiBeams, but the new house precipitated a financial disaster on 
>the budget.? I will
>have to wait two years to recover from this.
>
>So, I was wondering what to do in the interim.? Forty meters CW is 
>my favorite move.
>BUT, I am fully aware of the new sunspot cycle and the enhanced 
>operation in the higher bands.
>
>My initial plan was to just stake out a 40 meter ground plane in the 
>backyard.? They also
>work on 15 meters which would make me pretty happy.
>
>After a little thinking about it, it hit me that there is room for a 
>pair of phased verticals
>pointed end-fire in a NE direction and vice versa.? The question 
>is:? Can I make a pair of
>these work productively on 15 meters, as well?

Warren,

It sounds like you probably are intending to use 1/4 wl spacing on 
40m, which means 3/4 wl on 15m.  This is a little wide, but still 
useable.  Once you go past 5/8 wl spacing, the sidelobes start 
getting big.  It will still have useful gain in the main lobes, and 
interesting nulls, depending on the phase angle you use between the elements.

Of course, with a 3/4 wl vertical, the elevation pattern will have 
the highest signal at about a 45 degree takeoff angle (~4 dBi, for a 
single element, depending on ground losses), but the low angle energy 
at about 15 degrees is 3-4 dB down, or near 0.5 dBi gain.

In a two-element 15m array at a 15 degree takeoff angle, you should 
get about 4.6 dBi gain broadside (and 0.5 dBi sidelobes) with 0 
degree phasing, about 3.7 dbi gain with 90 degree phasing (three 
nearly equal gain lobes roughly 120 degrees apart), and approximately 
3.1 dBi gain with 180 degree phasing (a 4-lobed butterfly pattern 
with nulls broadside).  I can send you (or anyone else) pattern plots 
via direct e-mail if you're interested.

You're just in time for the onslaught of the spring breakers and the 
REALLY hot weather!  Enjoy your new digs.

73, Terry N6RY
Carlsbad, CA