Both antennas look the same on the outside but on the inside they are
totally different.
The loran works at 0.1 MHz, the com works at 130 Mhz.
The com antenna is resonant at near 1/4 wavelength and has an
impedance near 50 ohms.
Since the loran antenna is electrally short at 0.1% of a wavelength
the matching impedance is very high ( about 50,000 ohms ) hence this
is why the preamp is in the antenna with zero coax length to the
preamp. The preamp built into the antenna matches the 50K ohm antenna
impedance to the 50 ohm coax. You can get away from using a pre amp
but you must use a MUCH longer antenna feeding the coax or you will
not have any signal left by the time it gets to the receiver because
of the antenna to coax impedance mismatch.
The preamp power is fed down the signal coax from the loran receiver.
Due to this if you connect a grounded com antenna to the loran
receiver you will fry the power feed coupler in the loran receiver.
You can hook up a length of wire that is not grounded to see what
signal strength you get. You may be surprised at how long a wire it
takes to get the same signal strength as the amplified antenna.

If you transmit into a electrically short loran antenna you can kiss
it good bye because you just fried the preamp.
John

On 22 Dec 2004 23:00:48 GMT, (JFLEISC) wrote:

Can someone tell me the differences between a loran antenna and a comm or VOR
nav antenna? I guess what I'm looking for is why they would not be
interchangable, i. e. is the loran signal totally incompatible with others? is
it an absolute necessity for a preamp in the loran antenna (I would assume that
would eliminate the possibility of using that antenna to transmit, for
instance)? can a loran signal be received off of a dipole nav antenna? I'm
basically trying to be a little more knowledgable on the subject.

Jim