Antenna Spacing Formula

[mrtor]

Good morning everyone

Is there a specific formula for working out antenna spacing ?
I have done a quick search here on the board and haven't come up with an answer specifically relating to the lower power stuff.

My situation is:

I have 2 duplex systems 5 watts in power, the transmit frequencies are both in the 472 mhz range, the receive in the 477 mhz range

What is the minimum distance I can mount the antennas near each other without causing problems..

Thanks
Michael

[Nand]

Try this Michael.

http://www.rfsolutions.com/rfcalc1.htm

The minimum distance should be around 25 feet vertical spacing on UHF at 5 Watts for 64 dB isolation.

Nand.

[mrtor]

Try this Michael.

http://www.rfsolutions.com/rfcalc1.htm

The minimum distance should be around 25 feet vertical spacing on UHF at 5 Watts for 64 dB isolation.

Nand.

Thank you once again kind sir, you are a wealth of information

Regards
Michael

[RKG]

Note that the "vertical spacing" referred to in this calc means perfectly coaxial configurations, i.e., the antennas must be EXACTLY above and below one another. If the axes of the two antennas are offset by any amount, the formula doesn't work.

[RADIOMAN2002]

You might also try and combine the RX's into one duplexer(if they are close enough in freq)them into one antenna, then put the other TX antenna, at about 10 feet below the first. A general rule is that 10 ft verticle separation equals roughly 100ft horizontal.

[mrtor]

You might also try and combine the RX's into one duplexer(if they are close enough in freq)them into one antenna, then put the other TX antenna, at about 10 feet below the first. A general rule is that 10 ft verticle separation equals roughly 100ft horizontal.

That actually may be a better option for me, as the one point I forgot to make on the board in the first place was this is a PORTABLE situation on a customised trailer with 2 masts (1 front 1 back)

So I guess I now need to find a TX combiner and an RX combiner at a decent price !!!