Wireless Network Link Analysis

A service of Green Bay Professional Packet Radio ®


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Transmitter Side Specifications


Enter the highest transmitted frequency  
Enter the transmitter's RF power output  


Transmitter Side Cable & Antenna Specifications


Enter the transmitter's site name  
Choose the transmitter's external cable type  
If Other, enter the transmitter's cable loss specification   dB      per 100 meters    per 100 feet
Enter the transmitter's external cable length  
Enter the transmitter's antenna peak gain  
Enter transmitter's antenna radome loss1   dB
Enter the transmitter's site ground elevation (AMSL)  
Enter the transmitter's antenna center-of-radiation height (AGL)2  
Total number of transmitter cable connectors and/or adapters  
Enter any miscellaneous transmitter cable losses   dB    
Enter any miscellaneous transmitter gains (after cable loss)   dB    
Enter any miscellaneous transmitter path losses3   dB    


Receiver Side Cable & Antenna Specifications


Enter the receiver's site name  
Choose the receiver's external cable type  
If Other, enter the receiver's cable loss specification   dB      per 100 meters    per 100 feet
Enter the receiver's external cable length  
Enter the receiver's antenna peak gain  
Enter receiver's antenna radome loss1   dB
Enter the receiver's site ground elevation (AMSL)  
Enter the receiver's antenna center-of-radiation height (AGL)2  
The following four questions are for vertical space diversity systems only.
Enter receiver's vertical diversity antenna center-of-radiation height (AGL)2  
Enter the receiver's diversity antenna peak gain  
Enter the receiver's diversity antenna external cable length4  
Enter any miscellaneous receiver diversity antenna losses   dB    
Total number of receiver cable connectors and/or adapters  
Enter any miscellaneous receiver cable losses   dB    
Enter any miscellaneous receiver gains (before cable loss)   dB    
Enter the receiver's threshold (sensitivity)  
The following three questions are for digital data systems only.
If known, enter the receiver's dispersive fade margin (DFM)5   dB
If known, enter the receiver's external interference fade margin (EIFM)6   dB
If known, enter the receiver's adjacent channel interference fade margin (AIFM)7   dB


Transmit/Receive Antenna Distance & Environmental Specifications


Would you like to calculate the climate factor?   Yes   No
If No, choose the climate factor  
If Yes, answer the following two questions.
Enter the average terrain roughness (deviation of elevations)8  
Choose the local area humidity type  
Enter the average annual temperature  
Enter the estimated land usage factor9   percent
Would you like to calculate the effective Earth radius, K factor?10   Yes   No
If No, enter the effective Earth radius, K factor       
If Yes, answer the following two questions.
Enter the average annual relative humidity   percent
Enter the average annual barometric pressure   inches of mercury
Enter the precipitation rate   mm/hour
Select the N th Fresnel zone to calculate  
Would you like to calculate the path distance based on latitude & longitude?   Yes   No
If No, enter the distance between antenna sites  
If Yes, answer the following four questions.
Enter the transmitter site's latitude   (Use decimal degrees, positive is north)
Enter the transmitter site's longitude   (Use decimal degrees, negative is west)
Enter the receiver site's latitude   (Use decimal degrees, positive is north)
Enter the receiver site's longitude   (Use decimal degrees, negative is west)


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.

Notes

[1]  For sealed yagi antennas, radome loss is usually taken into account in the antenna's specified gain.

[2]  Antenna height and diversity antenna height should be measured from the antenna's center-of-radiation, usually the midpoint of the antenna.

[3]  Miscellaneous path losses are caused by ground reflections, atmospheric absorption, interference, rain/fog, billboards, vegetation, knife-edge diffraction, small farm animals, etc.

[4]  Diversity antenna cable type is assumed the same as the main receiver's.

[5]  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.

[6]  External interference fade margin is receiver threshold degradation due to interference from external systems.

[7]  Adjacent channel interference fade margin accounts for receiver threshold degradation due to interference from adjacent channel transmitters in one's own system.

[8]  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.

[9]  Land usage factor is the percentage of the path area covered by buildings of any type.

[10]  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 K
                                        Summer  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