"Caryl Duncan" wrote in message
...
Anyone know about this type of setup? My understanding is I must use 75
ohm coax from the ground up to the "T" then to each antenna. Is this true?
Anyone have a formula?

Use 75 ohm cable if your antennas are 50 ohm. Getting your antennas to be 50
ohms is nearly impossible. usually the actual impeadance of the antenna is
around 30 ohms so you can use 50 ohm cable instead of the 75. When you use
1/4 wavelength of 75 ohm cable on a 50 ohm antenna the the radio end of the
cable will look like 100 ohms. put the 2 100 ohms loads in paralell and now
they are 50 again. Use 75 ohm cable this with 30 ohm oantenna and you get 30
ohms at the radio one they are cophased. Use 50 cable and instead of
doubling the impedance of the antenna its now qradrupled so a single antenna
is seen as 120 ohms and the cophased set is seen as 60, a beeter match for
the 50 ohm radio.