I am contemplating on combining the signals from two antennas onto one
cable using some sort of an "RF combiner" (is this the right term? Is
"RF mixer" a better term?).

The idea is that I combine the signal from a dedicated omnidirectional
FM antenna and a dedicated omnidirectional VFH/UFH antenna, since I
have only one cable run in the house and I want to use it for both FM
and TV reception.

Does this idea make sense at all?

If so, what's the market name of this "RF combiner" device I should be
shopping for? Can you recommend a specific one? (does Radio-Shack have
such?)

Thanks,
Daniel

Hi Daniel

Generally a mixer in radio terms is a device where two frequencies are
input and the sum or difference of them is the output. So you are
talking about a combiner..

I think you'll have some trouble with your intentions.

It is relatively easy to combine the signals from two antennas and then
split them into two receiving devices. (The antenna combiner might be
the same as the splitter only connected the opposite way. Its usually a
passive device so will work equally well in both directions)

The problem is that since the bands of use are similar you cant stop
(say) the FM omni receiving some signal from the TV band transmission
appearing at the input to the TV. This will most likely cause ghosting
or other degradation.

I suspect that you mean unidirectional VHF/UHF antenna rather than an
omni. Using an omni is very likely to also create TV ghosting.

You could conceivably notch the output of the omni to not pass TV
signals but by now the project is getting kind of expensive.

I suggest you just use the one TV unidirectional antenna and have a
single splitter inside the house connected to the FM radio and TV. You
may get sufficient FM signal for your needs.

You are looking to buy a TV splitter to run two TV's in the house. Shd
be pretty cheap.

Cheers Bob VK2YQA

Daniel wrote:
I am contemplating on combining the signals from two antennas onto one
cable using some sort of an "RF combiner" (is this the right term? Is
"RF mixer" a better term?).

The idea is that I combine the signal from a dedicated omnidirectional
FM antenna and a dedicated omnidirectional VFH/UFH antenna, since I
have only one cable run in the house and I want to use it for both FM
and TV reception.

Does this idea make sense at all?

If so, what's the market name of this "RF combiner" device I should be
shopping for? Can you recommend a specific one? (does Radio-Shack have
such?)

Thanks,
Daniel

"Daniel" wrote in message
om...
I am contemplating on combining the signals from two antennas onto one
cable using some sort of an "RF combiner" (is this the right term? Is
"RF mixer" a better term?).

The idea is that I combine the signal from a dedicated omnidirectional
FM antenna and a dedicated omnidirectional VFH/UFH antenna, since I
have only one cable run in the house and I want to use it for both FM
and TV reception.

Does this idea make sense at all?

If so, what's the market name of this "RF combiner" device I should be
shopping for? Can you recommend a specific one? (does Radio-Shack have
such?)

Thanks,
Daniel

I think you're talking about a splitter - about $2
give it a try
by the way - that 300-ohm flat cable has lower loss than the coax so if you
have a long run from the antennas, keep that in mind



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Bob Bob wrote in message ...
Generally a mixer in radio terms is a device where two frequencies are
input and the sum or difference of them is the output. So you are
talking about a combiner..

You are right - I am talking about a combiner (some companies call it
a "joiner"?)

I think you'll have some trouble with your intentions.

It is relatively easy to combine the signals from two antennas and then
split them into two receiving devices. (The antenna combiner might be
the same as the splitter only connected the opposite way. Its usually a
passive device so will work equally well in both directions)

OK, so if I understand you correctly *any* splitter can work as a
combiner?

If so, do you have an idea why the following splitter is *not* labeld
as a combiner: http://tinyurl.com/kzr2, while the following:
http://tinyurl.com/6k5a9 is labled as such?

The problem is that since the bands of use are similar you cant stop
(say) the FM omni receiving some signal from the TV band transmission
appearing at the input to the TV. This will most likely cause ghosting
or other degradation.

I suspect that you mean unidirectional VHF/UHF antenna rather than an
omni. Using an omni is very likely to also create TV ghosting.

I didn't initially mean that (since I was hoping to receive more than
one station), but now that I read your explanation I have to accept
your suggestion. In fact, my current setting is a single
unidirectional FM/VHF/UHF antenna (http://tinyurl.com/52tjr) in my
attic, but because the space in the attic does not allow using a
rotator and because I have only one coax arriving to my living room, I
need some creative solutions to achieve the goal of having both the FM
and TV antenna signals arriving on a *single* coax to the living room
(afer which it can neatly be split behind the entertainment center
furniture).

You could conceivably notch the output of the omni to not pass TV
signals but by now the project is getting kind of expensive.

I don't mind spending a reasonable amount of money on a good solution.
Do you happen to know of such products (that would filter out TV
signal)?

I suggest you just use the one TV unidirectional antenna and have a
single splitter inside the house connected to the FM radio and TV. You
may get sufficient FM signal for your needs.

Currently this is indeed the situation, but because the antenna is
unidirectional, I can only receive certain FM radio stations - and I
miss some important (local) others. I find this unacceptable given the
fact that even my poor kitchen radio can receive all local stations
pretty well with a simple built-in whip antenna... Hence my idea of
installing an omnidirectional FM antenna in the attic and combining it
with the TV signal for the single coax.

BTW, if an omnidirectional TV antenna is *always* a bad idea because
of ghosting, how come such antennas are offered on the marketplace at
all? (such as the Winegard MS2000:
http://www.starkelectronic.com/wms2000.htm)?


Cheers Bob VK2YQA

Thank you so much, Bob!

Daniel


Daniel wrote:
I am contemplating on combining the signals from two antennas onto one
cable using some sort of an "RF combiner" (is this the right term? Is
"RF mixer" a better term?).

The idea is that I combine the signal from a dedicated omnidirectional
FM antenna and a dedicated omnidirectional VFH/UFH antenna, since I
have only one cable run in the house and I want to use it for both FM
and TV reception.

Does this idea make sense at all?

If so, what's the market name of this "RF combiner" device I should be
shopping for? Can you recommend a specific one? (does Radio-Shack have
such?)

Thanks,
Daniel