wrote:
Yes, you can reverse the splitter to make it combine the two signals
and keep the proper impedance. The only problem is.........the two
antennas may be located far enough apart that the signal induced
into antenna A may be out of phase with the signal induced into
antenna B. When this happens with an analog signal you may
get ghosting or just a reduced signal level that would not justify
using two antennas. With a DTV you may get a inferior signal level.
To reduce the possibility of out of phase antennas you should try to
mount them side by side so that the distance to the transmitting tower
is the same for both. On the upper frequencies a half wave or 100%)
phase shift is only 8 inches. On the lower frequencies it is around
2.5 feet. Keeping the antennas perpendicular and side by side is your
best bet. Signal deflection from mounting the antennas inside could
also cause a out of phase problem. Good luck.

Andy comments:
A very good answer .

One caveat..... The phase difference into the splitter from each
antenna will be not only spacing dependent, but ALSO frequency
dependent.... In other words, what will work fine at , say, 200 Mhz
may cause a deep null at another frequency, like ,say 300 Mhz.
And this will occur at multiple places in the VHF and UHF bands.
This may not be a problem, depending on where the stations
are located, frequency-wise.....

The best answer is to use a switch between antennae to select
the best signal. However, a splitter/combiner will save having to
throw the switch, IF it doesn't have phasing problems. You just
have to give it a try for your own specific location.

For the record, a properly designed splitter (2way) has an
internal
resistor that is only effective if one of the outputs is not
terminated
properly. If both outputs are terminated properly, the resistor does
nothing. The signal will be halved (3db) to each output, PLUS about
a half db of internal loss.

To learn more about splitters, go to a MINI-CKTS LAB website,
(you can google the address). They manufacture these components,
and have many tutorial papers on how they are built, and how they
should be used.

Andy in Eureka, retired RF engineer from Raytheon.