Jim Puglise wrote:
> There are multiple grades of coax and you want to use high grade coax
> and "type N" fittings.
I can't agree that an "N" connector verses BNC will add anything at VHF, Jim,
though
it would be better where it's subject to environmental contamination. I've
seen specs on factory male-female BNC connector pairs at a nothing .2db
insertion
loss, and even if user-fabricated connectors - true of any connector,
any additional loss is still very small.
At VHF also, any RG-58/whatever at less than 20 feet is perfectly adequate,
though
solid conductor is arguably not good mechanically. Lower-loss cable (400,
142) will be specified at transponder and GPS frequencies, though.
> The other thing I would do is build a simple
> vertical dipole and jury rig a piece of cable to the radio and try it.
The interesting thing about that is whether a 1/2-wave dipole behaves any
different
---From a 1/4-wave monopole whip antenna, if in free space (an airplane).
You'll
find long/lively threads about this on ham newsgroups, so I once posed the
question to an actual engineer from an actual aircraft antenna company. He
said that despite the stuff in many texts on antenna theory, they're exactly
the same well above the earth. At least it mostly answers the question as to
why airframe mfrs don't mind comm antenna installations on the top of fuselage,
contrary to the insistence of the 1/4-wave "half-donut" purists that it
shouldn't
work well at all where an ATC antenna is perforce below your altitude.
It's also been written that a dipole is more sensitive to interference from
nearby
metal elements than a monopole whip mounted inside a plastic airplane, but
if my antenna engineer friend is right, that might not be true either. Maybe
like the three rules of real estate valuation - location, location, location!
Regards,
Fred F.
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