In message , Ralph
Mowery writes

wrote in message
...
Dear John,

Stacking 2 HD6065P antennas in the same direction for gain you would mount
them 72" apart vertically from boom to boom. The phasing line will be 52"
long each +/- 1/8" of each other in length. The phasing lines will feed a
CC-7870 coupler to combine the signals. Your single output is now you
signal.

Cordially,
Hans Rabong
Tech. Service Manager.
Winegard Company

Unless I am missing something, seems like a waste of antenna and money.

I looked for the coupler and found this:

"You have the CC-7870 hooked up properly. However this coupler is just like
a 2-way splitter hooked up in reverse; in that it will reduce the signal
from each antenna by about 30%. "

If it is just a 2 way splitter in reverse, there is usually a 3 db loss and
all you get with 2 antennas is a gain of 3 db, so you gain nothing over a
single antenna with this coupler.

To get close to 3 db of gain you need to have a combiner of near zero loss.
This is often done by using an odd number of wavelenghts of feedline of a
differant impedance and hooking them in parallel to keep the impedance the
same. I doubt it would work very well over the while FM band,but may for a
small portion of it.

I don't know how big the antenna is, but you would be beter off with a
single larger antenna, or possiably an amplifier.
Maybe an even beter feedline.

Strange as it may seem, if you use (for example) a TV 2-way '3dB'
splitter to combine two identical in-phase signals, you DON'T lose 3dB.
Apart from the unavoidable slight inherent losses of the two
transformers the circuit uses (a total of around 0.5dB at low VHF,
increasing to 1dB at high UHF), the splitter is lossless. Ignoring the
transformer loss, the 3dB loss occurs simply because the power at each
output port is half of that at the input. You haven't actually lost
anything.

If the splitter is now turned around to become a combiner, it doesn't
suddenly become more lossy. If you again ignore the transformer losses,
the two identical in-phase signals you feed into the 'output' ports are
added, and the result is a signal 3dB higher.

An interesting experiment would be to cascade two splitters - the first
used as a splitter, and the second used to combine the two split signals
(via identical lengths of coax). The loss (because of the transformers)
should be only 1dB (low VHF) to around 2dB (high UHF), and not 7 to 8dB.
--
Ian