Duplex Antenna Placement

For full duplex llinks, antenna placement on the communications tower is critical to proper performace.  Full duplex links can cause significant interference to one another, where the output can overdrive the input radio.  Proper placement can augment the use of resonant cavities and other filters on the input and output of your full duplex system.
 

Above curves are based on the use of half-wave dipole antennas. The curves will also provide acceptable results for gain type antennas if (1) the spacing is measured between the physical centers of the antennas and if (2) one antenna is mounted directly above the other (collinear), with no horizontal offset. No correction factor is required for the antenna gains. Note: The values indicated by the curves are approximate values because of coupling, which exists between the antenna and tower. Increasing the antenna spacing beyond that shown by these curves may not always provide additional isolation because of antenna-tower coupling.

These curves are based on the use of half-wave dipole antennas. The curves will also provide acceptable results for gain type antennas if (1) the indicated isolation is reduced by the sum of the antenna gains and if (2) the spacing between the gain antennas is greater than 50 feet.