I think what Joe is really asking about is an near vertical incidence
skywave (NVIS) antenna. At least one study on these says they were
effective for stations at the lower points in the valley and frequently used
by the military in viet nam.
----- Original Message -----
From: "K4SAV" <RadioIR@charter.net>
To: <towertalk@contesting.com>
Sent: October 04, 2006 1:03 PM
Subject: Re: [TowerTalk] reflector for 75 meter inverted vee
> Adding a reflector sounds like a wasted effort. EZNEC says a gain
> increase of about 0.3 dB straight up.
>
> Assuming an inverted vee with the ends 30 feet below the apex, the
> height for max straight up gain is about 65 ft. Your antenna at 95 ft is
> only 1.5 dB below that for signals at 90 degrees elevation. The 95 ft
> antenna does have the same gain but the take off angle is about 46
> degrees.
>
> Even taking a lower antenna and feeding both antennas at various phase
> angles, I was unable to obtain any significant gain increase at 90
> degrees elevation. The simplest antenna I can think of that will
> increase the gain at 90 degrees elevation is a full wave horizontal loop
> at 50 feet. That will give you about 2.5 dB more gain than your inverted
> vee at 95 feet.
>
> It is possible to build arrays that squirt the signal straight up with
> significant gain, but the beamwidth is fairly narrow, and these antennas
> don't seem to have any applications in ham radio.
>
> Jerry, K4SAV
>
> Joe Barnes wrote:
>
>>I am considering putting up a wire about 1/4 wave below my 75 meter
>>inverted vee that is 10 percent longer than the inverted vee to use it
>>as a reflector for closer in ( within 700 miles or so) communications.
>>Does anyone have any experience with such a thing? The inverted vee is
>>at 95 feet at its apex. Thank you, joe barnes N4JBK
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>>
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