Combining antennas using a splitter

[Bill Gill]

In the OTA antenna thread I mentioned that I wanted to get
a UHF antenna to receive channel 35 from an out of town
station and hook it up through a reversed splitter to the
feed from my current antenna which receives the primary
(ABC, CBS, NBC, FOX, PBS) from the local stations. I was
told that there was no way that it would work.

Well I got news for the people who said it wouldn't work.
I just hooked it up and I now have good signal for Channel
35 along with the aforesaid major stations. The naysayers
may have had a point, but they just categorically said it
wouldn't work. Well, it does work, under some circumstance,
such as I am working with. One of the things that makes it
work is that the major stations in the Tulsa area all have
their transmitters in approximately the same location, at
least as far as direction from here goes. They are all
approximately ESE from here. Channel 35, which
is farther away is at just about right angles from the
major stations at just about NNE from here. That limits
some of the problems that may occur with 2 antennas.

Now I did lose a couple of channels that I was receiving
with my previous not very effective setup. I can't get
the Home Shopping Network, and a couple of religious
channels. I can't really get all worked up over those
losses, and I now have Channel 35 which I did want.

Bill Gill

[Jim Wilkins]

Post by Bill Gill
In the OTA antenna thread I mentioned that I wanted to get
a UHF antenna to receive channel 35 from an out of town
station and hook it up through a reversed splitter to the
feed from my current antenna which receives the primary
(ABC, CBS, NBC, FOX, PBS) from the local stations. I was
told that there was no way that it would work.
Well I got news for the people who said it wouldn't work.
I just hooked it up and I now have good signal for Channel
35 along with the aforesaid major stations. The naysayers
may have had a point, but they just categorically said it
wouldn't work. Well, it does work, under some circumstance,
such as I am working with. One of the things that makes it
work is that the major stations in the Tulsa area all have
their transmitters in approximately the same location, at
least as far as direction from here goes. They are all
approximately ESE from here. Channel 35, which
is farther away is at just about right angles from the
major stations at just about NNE from here. That limits
some of the problems that may occur with 2 antennas.
Now I did lose a couple of channels that I was receiving
with my previous not very effective setup. I can't get
the Home Shopping Network, and a couple of religious
channels. I can't really get all worked up over those
losses, and I now have Channel 35 which I did want.
Bill Gill

The potential problem is combining the -same- signal received on
multiple antennas. You may get interference similar to the garble from
multiple PA speakers and echos in a train or bus station.

[Stephen H. Fischer]

Hi,

Good luck in the future when the RF channels above 31 go away and new
building are put up.

90 Degrees in different directions is a major factor that allows your
situation to work along with the RF frequencies being separate.

You, for the time being have actually built a notch filter and a bandpass
filter ahead of the reverse splitter and may not have mountains all around
creating multi-path like many people do.

I suggest that you keep notes on what channels you get and do not get so you
can understand why it does not work in the future like you need.

Soon I will have two stations transmitting on the same RF at different
distances away along the same path using the same Virtual Channel (Same
station actually) and two more on another RF not quite in the same direction
again using the same Virtual Channel (Same station actually).

Plus a HUGE list of stations approved by the FCC but not on the air yet that
should they go on the air they may cause me problems ahead of the big
upcoming RF DTV Crunch.

I may lose some stations as I do not have a working VHF-Low antenna
(Actually it is in a partial Faraday cage) and the new multi-path field of
the new RF frequencies may not be solvable with the four antennas connected
to seven (7) tuners and I may need to just go back to reading books.

http://www.choisser.com/sfonair.html

SHF

Post by Bill Gill
In the OTA antenna thread I mentioned that I wanted to get
a UHF antenna to receive channel 35 from an out of town
station and hook it up through a reversed splitter to the
feed from my current antenna which receives the primary
(ABC, CBS, NBC, FOX, PBS) from the local stations. I was
told that there was no way that it would work.
Well I got news for the people who said it wouldn't work.
I just hooked it up and I now have good signal for Channel
35 along with the aforesaid major stations. The naysayers
may have had a point, but they just categorically said it
wouldn't work. Well, it does work, under some circumstance,
such as I am working with. One of the things that makes it
work is that the major stations in the Tulsa area all have
their transmitters in approximately the same location, at
least as far as direction from here goes. They are all
approximately ESE from here. Channel 35, which
is farther away is at just about right angles from the
major stations at just about NNE from here. That limits
some of the problems that may occur with 2 antennas.
Now I did lose a couple of channels that I was receiving
with my previous not very effective setup. I can't get
the Home Shopping Network, and a couple of religious
channels. I can't really get all worked up over those
losses, and I now have Channel 35 which I did want.
Bill Gill

[Bill Gill]

Post by Stephen H. Fischer
Hi,
Good luck in the future when the RF channels above 31 go away and new
building are put up.
90 Degrees in different directions is a major factor that allows your
situation to work along with the RF frequencies being separate.
You, for the time being have actually built a notch filter and a
bandpass filter ahead of the reverse splitter and may not have mountains
all around creating multi-path like many people do.
I suggest that you keep notes on what channels you get and do not get so
you can understand why it does not work in the future like you need.
Soon I will have two stations transmitting on the same RF at different
distances away along the same path using the same Virtual Channel (Same
station actually) and two more on another RF not quite in the same
direction again using the same Virtual Channel (Same station actually).
Plus a HUGE list of stations approved by the FCC but not on the air yet
that should they go on the air they may cause me problems ahead of the
big upcoming RF DTV Crunch.
I may lose some stations as I do not have a working VHF-Low antenna
(Actually it is in a partial Faraday cage) and the new multi-path field
of the new RF frequencies may not be solvable with the four antennas
connected to seven (7) tuners and I may need to just go back to reading
books.
http://www.choisser.com/sfonair.html
SHF

I understand that I have what amounts to a special case. What
I am saying though is that a blanket statement "You can't do
that" is not adequate. In science a theory is true until somebody
makes an observation that clashes with the theory. Your blanket
statement fails, because I have made an observation that clashes
with it. So I suggest that you not go around making such
blanket statements without qualifying them.

Bill

[Jim Wilkins]

Post by Stephen H. Fischer
Hi,
Good luck in the future when the RF channels above 31 go away and
new building are put up.
90 Degrees in different directions is a major factor that allows
your situation to work along with the RF frequencies being separate.
You, for the time being have actually built a notch filter and a
bandpass filter ahead of the reverse splitter and may not have
mountains all around creating multi-path like many people do.
I suggest that you keep notes on what channels you get and do not
get so you can understand why it does not work in the future like
you need.
Soon I will have two stations transmitting on the same RF at
different distances away along the same path using the same Virtual
Channel (Same station actually) and two more on another RF not quite
in the same direction again using the same Virtual Channel (Same
station actually).
Plus a HUGE list of stations approved by the FCC but not on the air
yet that should they go on the air they may cause me problems ahead
of the big upcoming RF DTV Crunch.
I may lose some stations as I do not have a working VHF-Low antenna
(Actually it is in a partial Faraday cage) and the new multi-path
field of the new RF frequencies may not be solvable with the four
antennas connected to seven (7) tuners and I may need to just go
back to reading books.
http://www.choisser.com/sfonair.html
SHF

I'm getting by with a UHF-only antenna aimed at Boston and a UHF+VHF
on a rotor for stations elsewhere, patched as necessary through two
distribution amps and cables to my 5 tuners and spectrum analyzer.

The usual single-channel configuration is both antennas into an A-B
switch whose output goes to the 4-way amp. The coax to the computer
desk runs into an A-B switch that selects either the TV or a computer
tuner. Most of the coax ends in push-on F connectors to make
repatching easier, such as temporarily into a splitter to watch both
the TV and the computer.

If the power goes out I reconnect the antenna directly to a laptop +
USB tuner, which serves as a battery-powered TV, powered by an
Auto-Air charger running from a car jump starter. A small UPS is
enough to power the rotor controller for a few seconds to reaim the
VHF+UHF antenna. The UPS and jump starter safely contain a 12V battery
in the living room.

There are too many possible combinations for a pure switch matrix that
I'd rarely change. One amp per antenna gives me all the versatility
I've needed.

[G-squared]

Post by Bill Gill
In the OTA antenna thread I mentioned that I wanted to get
a UHF antenna to receive channel 35 from an out of town
station and hook it up through a reversed splitter to the
feed from my current antenna which receives the primary
(ABC, CBS, NBC, FOX, PBS) from the local stations. I was
told that there was no way that it would work.
Well I got news for the people who said it wouldn't work.
I just hooked it up and I now have good signal for Channel
35 along with the aforesaid major stations. The naysayers
may have had a point, but they just categorically said it
wouldn't work. Well, it does work, under some circumstance,
such as I am working with. One of the things that makes it
work is that the major stations in the Tulsa area all have
their transmitters in approximately the same location, at
least as far as direction from here goes. They are all
approximately ESE from here. Channel 35, which
is farther away is at just about right angles from the
major stations at just about NNE from here. That limits
some of the problems that may occur with 2 antennas.
Now I did lose a couple of channels that I was receiving
with my previous not very effective setup. I can't get
the Home Shopping Network, and a couple of religious
channels. I can't really get all worked up over those
losses, and I now have Channel 35 which I did want.
Bill Gill

The splitter can work as you found out. If you went after your system with a spectrum analyzer you might find frequency response quirks from cancellations but as long as the irregularities are within the correction range of the receivers you'll never know. There ARE frequency selective combiners but they aren't cheap.

http://www.warrenelectronics.com/antennas/Jointennas.htm

I use 2 antennas but only to combine UHF on the roof with a VHF antenna above the garage. For that I can use a plain old UHF/VHF splitter just running in reverse.

I'm glad you tried it and found it to work.

G²