I am going to be heading out to get the bits for a 2m/70cm quad with 7 ele each band...
It would be worthwhile modeling that antenna first to see how much interaction there
is between the bands - the 2m elements will have resonances near 435 MHz, so the
70cm pattern might not be as clean when they are built on the same boom.
I'd like to put my 4 ele 6m beam up on one side of the AZ/EL rotor with the interlaced quad on the other. I have heard you need to space the uplink and downlink antennas about 6 ft but I have also seen very active sat folks successfully using antennas that interlace 2m and 70cm.
Presuming your receiver is adequately protected from your transmitter signal, the
issue becomes one of interaction among the elements (and with the mast and/or
boom, depending on the relative polarization of the antennas.)
If the antenna is vertically polarized, it needs to be far enough out from the mast
(which is also vertical) to avoid pattern distortion. With horizontal polarization the
cross-boom (which is also horizontal) becomes more important if it is made of
conductive material.
In some cases you may also want to vary the spacing to balance the weight of
the antennas at the rotator - this may mean putting the lighter antenna further
out from the mast. (But you also want to try to keep the wind forces equal on
each side of the rotator.)
... is there any benefit to using a quad in a horizontal polarization versus a diamond configuration.
A quad can be in the diamond configuration and STILL be horizontally polarized. Or
vertically. Same with square elements.
A quad is horizontally polarized if it is fed at the center top or bottom of the driven element,
regardless of whether the element is square, diamond, rectangular, septagonal, or round. It
is vertically polarized when fed at the center of one vertical side of the element.
