On Wednesday, March 11, 2015 at 7:11:14 PM UTC-4, Brian Reay wrote:
Tom W3TDH wrote:
I am looking for recommendations for a dual band antenna that will serve
two separate radios. The reason that I want to use a single antenna is
that I have a limited number of mounting points for antennas. At present
it will be hard for SWMBO; as in Rumpole's spouse, She Who Must Be
Obeyed; to tolerate the use of both our home's gable ends and the chimney
being used to support antennas. I am planning to replace my Diamond X-30
with a triband vertical for Six, Two, and .7 Meters. The chimney will
then support a rotor aimed Two and .7 Meter beam. The second gable end
will support the Two meter / Seventy Centimeter dual band vertical that I
am asking for help in selecting.

One radio will be a two meter packet node which will be used as a Winlink
Radio Message Server. The other radio will be a UHF D-STAR hotspot. I
am willing to pay what is needed to to get the best antenna for this
application but I don't want to waste money ineffectively. So the two
meter radio will be in the 144 MHz portion of the band and I don't yet
actually know were the D-STAR hotspot will be run. I have a DCI filter
and diplexer to keep the two radios from actually knowing of each others
existence. Since a hotspot is not supposed to be a terribly wide area
installation I would imagine that I do not want an extremely high gain
antenna but I am perfectly open to be reeducated on that. The difficulty
is that I would guess that the Radio Message Server / Packet would
benefit from as much horizontal gain as can be achieved. I have a home
brewed collinear two meter J-Pole that has been a good performer on two
meters and presents a low SWR on 440 MHz. I have yet to master antenna
modeling but I would imagine; given all the warnings I have read on line;
that it has poor radiation pattern on UHF. Is it likely to be too poor a
performer for a hot spot on UHF?

I really am asking because I want to know. I am not looking for
encouragement to do something that will be ineffective. Thank you in
advance for any help you may be willing to offer.

--
Tom Horne W3TDH

Diamond do a number of other antennas similar to the x30, essentially
longer, with more gain. I would suggest you look at their website and pick
one to match you budget, acceptable profile, etc.

It may be worth investing in another tribander, you may just want the third
band in the future and it will save another negotiation with Senior
Management. Or you could take my approach and have an XYL who is licensed
;-)

73
Brian
G8OSN/W8OSN

Brian

Should I follow your suggestion I would need to also provide protection for the radio connected to the third band segment. Do you know of any reason why connecting two separate filters to the same feed line would not work.

Can I anticipate any ill affect from placing a coaxial Tee fitting across the output of one filter and connecting a jumper to the output of another filter in order to connect the transceivers to the multiband antenna? Would there be any additional concerns be raised if one of the two filters was the dual band model with separate connections for each of it's two bands on the end being used for input connections? What about if I make up the assembly using Three separate filters with Two of them connected to TEE fittings..

--
Tom Horne W3TDH