A service of Green Bay Professional Packet Radio ®
|Transmitter Side Specifications|
AGL Above Ground Level. Height above common ground to the midpoint of the radiating antenna.
AMSL Above Mean Sea Level. Height referenced above sea level, or zero elevation.
This script is not frequency dependant, though the minimum frequency is 20 MHz and things get hairly above 40 GHz.
Assumes 0.1 * sqrt(Frequency_in_GHz) dB loss for each coax connector or adapter.
Antenna polarization losses are estimated, real world examples vary greatly.
Some sources of interference are in-band signals originating from other systems, reflections, multipath and receiver front-end overload produced by adjacent transmitters, such as MMDS/MDS/radar etc.
 For sealed yagi antennas, radome loss is usually taken into account in the antenna's specified gain.
 Antenna height and diversity antenna height should be measured from the antenna's center-of-radiation, usually the midpoint of the antenna.
 Miscellaneous path losses are caused by ground reflections, atmospheric absorption, interference, rain/fog, billboards, vegetation, knife-edge diffraction, small farm animals, etc.
 Diversity antenna cable type is assumed the same as the main receiver's.
 Dispersive fade margin is provided by your radio's manufacturer, and is determined by the type of modulation, effectiveness of any equalization in the receive path, and the multipath signal's time delay. Dispersive fade margin characterizes the radio's robustness to dispersive (spectrum-distoring) fades.
 External interference fade margin is receiver threshold degradation due to interference from external systems.
 Adjacent channel interference fade margin accounts for receiver threshold degradation due to interference from adjacent channel transmitters in one's own system.
 Example standard deviation of the terrain elevations: 6 meters - for smooth and over-water terrain, 15 meters - for average terrain with some roughness, 43 meters - for mountainous or very rough terrain.
 Land usage factor is the percentage of the path area covered by buildings of any type.
 The K factor accounts for refraction of radio waves close to the surface of the earth. For antenna towers less than a couple of thousand feet above the surface, a K factor of 1.33 is usually adequate for most line-of-sight calculations over average terrain.Typical Values of KSummer Winter Dry mountains (above 1500 meters) 1.20 1.20 Mountains (to 1500 meters) 1.25 1.25 Midwest and Northeast 1.50 1.30 South and West Coast 1.55 1.35 Southern Coast 1.60 1.50