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Old July 21st 04, 08:10 PM
T.C. Mann
 
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Default Connecting 2 Antennas to 1 Feedline

This question may be slightly offtopic but I figured I would post to
the group that knows antennas best. I have 2 TV antennas, one VHF and
one UHF, that I would like to combine to use a single coax feed. The
specs on a suitable joiner state it has .5dB insertion loss with 30dB
rejection between ports. The specs on a typical splitter are 3.5dB
loss and only 20dB between ports. The question I have is why would
anyone ever use a splitter instead of a joiner? Are there any
applications where you couldn't use a joiner instead of a splitter?
Thank you.
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Old July 21st 04, 11:01 PM
Tam/WB2TT
 
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"T.C. Mann" wrote in message
om...
This question may be slightly offtopic but I figured I would post to
the group that knows antennas best. I have 2 TV antennas, one VHF and
one UHF, that I would like to combine to use a single coax feed. The
specs on a suitable joiner state it has .5dB insertion loss with 30dB
rejection between ports. The specs on a typical splitter are 3.5dB
loss and only 20dB between ports. The question I have is why would
anyone ever use a splitter instead of a joiner? Are there any
applications where you couldn't use a joiner instead of a splitter?
Thank you.


They are different things. A joiner separates (or combines) the UHF from the
VHF with filters. That is why there is so little loss. If you used one to
feed two TVs, one of the TVs would get the UHF, the other the VHF. The
splitter is more or less frequency independent, and feeds half the power to
each output.

Tam/WB2TT


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Old July 22nd 04, 11:25 AM
Fractenna
 
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The specs on combiners are always tough to figure out. What most people think
of as 'insertion loss' is actually division loss. The1 to 2 splitter with 3.5
dB insertion loss probably claims 3 dB of division loss --and 0.5 dB
dissipative loss.

Its very unlikely its 3.5 dB of dissipative insertion loss. Even cheap power
dividers--which are split delay networks with chip resistors--tend to be better
than 3 .5 dB of dissipative loss, when they work.

73,
Chip N1IR
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