KP7UC wrote:"I dont understand what your design of the "enclosed angle ...is
about 30-35 degrees ...for a correct apex angle.." means?"The legs of a Vee are
long wires. Long wires antennas have the radiation lobes at an angle with
respect to the wire that depends on how many wavelenghts long the wire is. The
longer the wire the smaller the angle between the main lobes and the antenna
wire. You can see the graph angle versus wavelenghts and gain in the Long Wire
and Traveling Wave Antennas chapter of most editions of the ARRL Antenna Book.
That information is good for long wires, vees and rhombics as well. The
included angle of the vee must be twice this angle so the main lobes of both
legs are aligned on the center of the vee for best pattern and gain. The lenght
in wavelenghts varies with the frequency so does the lobe angle, you must
determine your apex angle depending on the frequency range and the band you
want to favor the most among other things.The value of 30-35 deg
rees is an optimum apex angle for a Vee or a rhombic if the legs are 8 - 9
wavelenghts long, if am not wrong.73David HK1AEC5KXAex-HK1KXA
> From: firstname.lastname@example.org
> To: email@example.com
> Date: Sat, 10 Apr 2010 21:30:17 -0700
> Subject: Re: [TowerTalk] V beam leg lengths
> I had a 50 foot v beam up at about 70 feet for several years but finally
> took it down because my triband yagi perforned better (except 40m). Its apex
> angle was fixed at about 50 degrees. That apex angle was selected as a
> compromise from a graph in an older ARRL antenna book.
> I took the vee beam down after I modeled it with EZNEC and learned how the
> apex angle effects the maximum gain (vs broad beam).
> I have thought of putting up several wires and selectng the apex angle with
> relays like you are designing. However to get a gain better than a simple
> Yagi requires a pretty narrow apex angle which means a lot of wires and
> relays ( if you want to steer the direction).
> I dont understand what your design of the "enclosed angle ...is about 30-35
> degrees ...for a correct apex angle.." means?
> I urge you to model your proposed design.
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