My step father had a indoor aerial, it was heap of rubbish, the house was
in view of the transmitter,
if you walked around, the color would come & go, I took it apart, there
was no balum the earth was going direct to one rod and the active part
of the coax was going direct to the other rod,

I made a balum for it, after much experiment (reinventing the wheel using my
aerial theory) came up with the "standard 75 to 300 Ohm balum" giving the
best result. After that the color stayed when you walked around the room.

It seems to me a lot of people don't know "Jack ****" about the indoor
aerials or aerial theory when it comes to talking about them, including the
people who make them.



"Sofie" wrote in message
...

"Eric" wrote in message
Does anybody know of a technical report of the "indoor aerial" I was told
a
few years ago the there is no resemblance between the rabbits ears and
aerial theory, just I have a few people who want to argue the point, and
hoping there might be a URL around that might show I'm right or partly
right.
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Eric:
Actually, since rabbit ears are an "open dipole" not a folded dipole, the
impedance of a simple dipole is closer to a nominal 75 ohms..... and that
is only the case if the ears are in a straight line and are not in a
typically found "V" formation. Since rabbit ears are fed with a 300 ohm
twin-lead and usually fed into a 300 ohm to 75 ohm transformer/adapter so it
will plug into the 75 ohm "F" connector on the back of a television or
VCR....... all of these mis-matches significantly reduce the efficiency on
the whole operation...... however..... since rabbit ears are usually only
used in local strong signal areas all of these mismatches in reality are
simply overlooked..... and can work surprisingly well in some areas.
A "folded" dipole, similar to the cheap FM tuner "T" antennas, is optimally
a 300 ohm device and are usually made entirely out of 300 ohm twin-lead
including the nominally 5 to 6 foot long horizontal antenna element that
forms a closed loop.... or "folded dipole." Some cheaper versions of the
FM "T" antenna do not utilize 300 ohm twin-lead and are just a simple "open"
dipole and are usually and properly connected to the 75 ohm terminals on the
back of the FM tuner.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
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