In general, you need 4 adjustments to get two antennas properly
phased and matched to 50 ohms. This can be done with two
matching networks. The transmitter goes through the first matching
network and drives the first antenna. The input of the second
matching network is connected in parallel with the first antenna
and its output goes to the second antenna. You need to have
a way of determining when the phasing is right. Usually tuning
for maximum F/B ratio is a poor man's way of doing this. More
"scientific" methods are described on my web site.
As far as no one on this reflector mentioning this, I have been
advocating this empirical technique for years and it is written
up on my web site. For whatever reason, it doesn't seem to be
popular. Anyway, it has worked well for me.
Rick N6RK
Dennis Ventler wrote:
>
> I am surprised that no one on this reflector has never mentioned using a "T"
> phasor for phasing either two verticals or two horizontal dipoles. Yes,
> there is a very complex phases due to close proximity between the two phased
> antennas but the "T" phasor is adjustable and the correct phase can be set by
> adjusting the variable capacitor's value and adjusting the inductor with a
> tap on the coil. The "T" phasor is very simple to make with both variable
> capacitor and a coil in series. The junction of the two items is attached to
> the transceiver antenna input. The other side (open end) of the coil and
> capacitor go to each of the two antennas. You will need a DPDT relay to flip
> flop the ends that go to each antenna for changing the desired direction.
> The feed lines need to be exactly the same length and I prefer them to be
> even wave lengths. The SWR is better with them that way. Adjustment for
> best front to back can be made on receive and one doesn't have to worry
> about
the complex phasing relationships. I have had very good success using this
technique on 40 Meters for about 30 years or so. When adjusted properly, one
should see around 20 DB front-to-back most of the time. Of course, there are a
lot of variables like distance between the station being worked and antenna
height. When properly adjusted, you might have as much as a two to one SWR but
I have always used a tuner in the line to keep everything flat to the
transmitter or amplifier. By the way, directivity or forward gain will be the
antenna that connects to the capacitor. If one choose to use two dipoles
instead of verticals, make sure that the center conductor of the coax goes to
the same side with each antenna.
>
> If anyone is interested in this phasing method and has questions, feel free
> to Email me directly.
>
> 73 DE W9JDJ, Denny
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