Interesting Eric, assuming he has a very tall mast, hence the use of duplexers, now UHF, a lot easier
73 Steve ----- Original Message ----- From: "Eric Lemmon" <[email protected]> To: <[email protected]> Sent: Sunday, August 29, 2010 6:40 PM Subject: RE: [Repeater-Builder] ariels > Antony, > > For a rough approximation, one must know the following information: > Transmitter frequency in MHz, Transmitter power in Watts, Receiver > frequency > in MHz, and Receiver sensitivity in microvolts or dBm. > > As an example, let's assume that your repeater transmits at 147.300 MHz > with > 50 watts, and receives at 147.900 MHz with 0.3 microvolts of sensitivity. > My CommShop software program estimates that about 89 dB of isolation > between > TX and RX is needed, and this isolation can be met with separate antennas > 220 feet apart vertically or 21,782 feet apart horizontally. Obviously, > horizontal separation of more than four miles is impractical unless a link > radio is used. The vertical arrangement is assumed to be in line, with > one > antenna exactly above the other. Although vertical separation is > practical > when a tall tower is available, the use of Heliax or similar hardline with > 100% shielding is mandatory. Keep in mind that programs such as CommShop > make some assumptions about your radios that may be erroneous. YMMV... > > 73, Eric Lemmon WB6FLY > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of antony > Sent: Sunday, August 29, 2010 2:35 AM > To: [email protected] > Subject: [Repeater-Builder] ariels > > > > using two radios as a repeator with two ariels. how far appart would the > ariels be best. thanks antony > > > > ------------------------------------ > > > > Yahoo! Groups Links > > >
