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Two antennas into one Scanner

PostPosted: Wed Jun 20, 2018 8:56 pm
by Throbber
Hey guys, just a simple question, can i have my Aviation J Pole and my general 25 - 1300 mghz antennas run into my BCT 15X scanner using a tee ??

If not, why not

Thanks

Re: Two antennas into one Scanner

PostPosted: Wed Jun 20, 2018 9:59 pm
by Metradio
Have a go at it and find out for yourself... nice experiment..

Mike

Re: Two antennas into one Scanner

PostPosted: Wed Jun 20, 2018 11:08 pm
by m0lsx
There are antenna switches available if you want to do it, so that you switch between the two, or more than two, antennas into one radio. So yes.
However if you want to run both of the antennas into one radio using a simple T joint, then the answer is probably no, not with a wideband receiver.
However on a single band the answer is yes, it can be done & it is fairly common on the VHF amateur radio SSB bands where some operators run multiple, phased, beams. However, there are real potential problems if you do it wrong. As you need to phase the antennas. And if you get the phasing wrong, each signal will cancel out the other signal out & potentially completely.
But get it right & you can make two verticals directional & with real signal gains.
Another issue is that two 50 Ohm antennas should produce 25 Ohms at the radio, so your phasing coax, also needs to be impedance matching too.
Phasing means you insert an appropriate length of coax between the two antennas, so that the coax length & it's velocity factor, gives you correct phase for each signal at the radio, so that each signal adds to the other & not subtracts from it. And I do not think you can phase a wideband antenna.
The above, about phasing. Is how I remember it from my Advanced licence course.

Re: Two antennas into one Scanner

PostPosted: Wed Jun 20, 2018 11:10 pm
by m0lsx
Phased verticals are also common on some American trucks. As they want the best signal/reception at the front & back on long straight roads.

Re: Two antennas into one Scanner

PostPosted: Fri Jun 22, 2018 9:13 pm
by Throbber
Watcha guys, OK i gave it a go with a simple "T" without success.
It seems that when both Antennas are connected i get far less signals received, tried it for 2 hours and there was definate loss of signal.

Thanks for the replies.

Throbber

Re: Two antennas into one Scanner

PostPosted: Sat Jun 23, 2018 9:56 pm
by Metradio
Throbber wrote:Watcha guys, OK i gave it a go with a simple "T" without success.
It seems that when both Antennas are connected i get far less signals received, tried it for 2 hours and there was definate loss of signal.


Trying it for yourself gives you more information than pages of findings from others..
Every day a school day :smiles:

Mike

Re: Two antennas into one Scanner

PostPosted: Sat Jun 30, 2018 11:38 pm
by Throbber
Trying it for yourself gives you more information than pages of findings from others..
Every day a school day :smiles:

Mike


Totally agree Mike :embarrased: