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what should be the minimum antenna distance for a repeater without duplexer?

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aq_mishu

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guys,
i'm building a UHF repeater. It's on GMRS freq. My location is in Bangladesh. I'm planning to just use two 4W HTs as a TX and RX. as said, GMRS, means UHF, the separation will be 5MHz. Say GMRS ch 1.

Now, I will also use a 45W Base for the same project (2 different location, 2 different purpose).

As this is a total homebrew issue and as there is no way for me to get a duplexer, I'm planning to use two seperate antenna for TX and RX. feed will be through RG58AU. What should be my minimum gap between the two antennas??

I may use folded dipole or half wave dipole or ground plane, but less possibility of groundplane as material is not available there.

I'll be very thankful..

Mishu~
 

Only an RF System analysis (including radiated TX power and antenna gain) it will tell you the answer. Is related to a lot of system requirements that the receiver should met. As: sensitivity, intermods, blocking, etc, factors that are influenced by the transmitter in a half or full duplex RF system.
Generally a duplexer gives about 50dB isolation between TX and RX, so the antenna isolation (if the duplexer is not used), should be about the same, maybe more.
 

Many thousands of feet. I know of a commercial repeater site where the two halves are on two different mountain tops.
 

so there is no way other than a duplexer???

I saw repeaters with two individual Tx-Rx ant connections...

The ant gain is 3dBi. Tx power is 45W. FRS band. receiver sensitivity is 18uV.

Mishu~
 

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