Best way to connect a rabbit ears type antenna to a coax cable

[CJVx]

Sort of an indirect question. Here is the story. In my attic, I have a rabbit ears antenna connected with 300 ohm flat cable to my tuners’ (one at a time of course) 300 ohm antenna connections. I am very satisfied with its performance.

I also have one of those Amazon uni directional 75 ohm coax antennas in the attic connected through a coax cable. When used with a tuner that has a 75 ohm input, this antenna does not perform as well as the rabbit ears setup I have, when run into the same tuner’s 300 ohm input.

I would like to use this coax cable run, but replace the Amazon uni antenna with rabbit ears. I hear matching transformers are lossy, so the question is, can I simply have one rabbit ear to the shield and the other to the center conductor? Or would I be better off with a matching transformer? Also, what impedance would any of these configurations be?

 

[tom3]

Don't have an answer but I have often wondered about this too. My digital TV antenna has two connectors with a twin lead connection to a match trans to a 75 ohm cable to the preamp with 75 ohm output cable to the TV. Seems like that matching transformer right off the antenna would be a huge loss considering the weak signal there. I live in a deep fringe area and need all the signal I can get. Also I have used an outside FM antenna in the garage and that really does the job for radio.

 

[dr*audio]

Cut the 300 Ohm twin lead about 2" from the antenna and attach a 75 Ohm balun to it.

 

[drjim]

Cut the 300 Ohm twin lead about 2" from the antenna and attach a 75 Ohm balun to it.

aka a "Matching Section".....

 

[audiotemp]

I would like to use this coax cable run, but replace the Amazon uni antenna with rabbit ears. I hear matching transformers are lossy, so the question is, can I simply have one rabbit ear to the shield and the other to the center conductor? Or would I be better off with a matching transformer? Also, what impedance would any of these configurations be?

Plain rabbit ears by themselves don't match up to very well to either twin lead or coax cable. Typically they have some matching inside the base.

The ears themselves are roughly 75 Ohm but with coax cable there is also the issue of balanced to unbalanced conversion. if coax is attached directly to the antenna, the braid (shield) of the coax will act as a 2nd antenna which then interferes with the rabbit ears. This situation is prevented with a balun, of which there are several types. With twin lead, pickup in the cable is almost equal in both leads, leading (at least in theory) to no interfence.

The TV converters work for matching 75 Ohm unbalanced to 300 Ohm balanced, which is not the right conversion for matching raw "ears" to either cable. They do work for converting ears matched to twin lead over to use with coax, and vice versa, but then you have two layers of matching which is what leads to excess loss.

 

[vwestlife]

What kind of "Amazon uni-directional 75 ohm coax antenna"? Some TV antennas purposely notch out the FM band to help prevent strong local radio stations from interfering with TV reception. And many newer TV antennas are really only designed for UHF, and have poor VHF/FM reception.