Coupling Antennas

[hgm16f]

I live in a area just north of South Bend, IN. South Bend is the local channels (UHF). I use two antennas, one UHF only for South Bend and one Hi gain UHF/VHF for Chicago. Both antennas are mounted on a 40' tower. I use antenna switches to change from one antenna to the other.

The U/V antenna is a Wineguard older type with a antenna mounted preamp (1970 vintage). The UHF is a higain UHF only.

I am trying to couple the two antennas together to eliminate the need for the switches, Using a CC-7870 when ever I plug the UHF into coupler I loose all hiband VHF and UHF from Chicago antenna.

Any Help.

[winegard]

Good morning hgm16f -

You do not state how far you are from either city. What is sounds like is happening is that you are getting Chicago signals on the side of the South Bend antenna. Now when you try to combine the 2 antennas the 2 Chicago signals mix and are out of phase causing the signals to cancel each other. In some cases depending on signal levels and phasing problem a coupler can not be used and the only option you have is to use separate leads and switches.

[hgm16f]

About 60 mi from Chicago and < 30 miles from the South Bend transmitting antennas. I receive no Chicago stations on my UHF only antenna. The antennas are pointed 90 degrees apart the UHF is at 180 deg and the Chicago is at 270 deg azmuth. If there is a phase problem why does it effect the high VHF only??

[winegard]

The 2 antennas need to be at least 4 feet apart. Will the Chicago channels go through the CC-7870 coupler with the South Bend antenna lead disconnected? If so then the there is a bleed over problem from the South Bend antenna. Even though the antennas are at 90 degrees you can still pick up Chicago signal on the side of the South Bend antenna.

You might try a 3dB or 6dB attenuator pad on the South Bend antenna to see if the reduction of the South Bend signal will have any affect. If the Chicago channels do not go through the CC7870 coupler with the South Bend antennas disconnected then your signal is too weak and you will need to amplify the signal more before the coupler which has a 30% signal loss.