Enter the highest transmitted frequency   MHz GHz

Enter the transmitter's RF power output   dBm milliwatts watts dBW kilowatts dBk

Transmitter Side Cable & Antenna Specifications

Enter the transmitter's site name

Choose the transmitter's external cable type   Times Microwave LMR-400 Times Microwave LMR-400 UltraFlex Times Microwave LMR-500 Times Microwave LMR-600 Times Microwave LMR-900 Times Microwave LMR-1200 Times Microwave LMR-1700 Andrew Heliax LDF4-50A Andrew Heliax LDF5-50A Andrew Heliax LDF6-50A Andrew Heliax LDF7-50A Belden 9913 (RG-8) Belden 8267 (RG-213) Belden 9258 (RG-8X) Belden 8240 (RG-58) Crap RG-8 Other

If Other, enter the transmitter's cable loss specification   dB      per 100 meters    per 100 feet

Enter the transmitter's external cable length   meters feet

Enter the transmitter's antenna peak gain   dBi dBd

Enter transmitter's antenna radome loss1   dB

Enter the transmitter's site ground elevation (AMSL)   meters feet

Enter the transmitter's antenna center-of-radiation height (AGL)2   meters feet

Total number of transmitter cable connectors and/or adapters

Enter any miscellaneous transmitter cable losses   dB     -- Examples -- 2-port splitter, 3.5 dB loss 4-port splitter, 6.5 dB loss PolyPhaser, 0.2 dB loss Right angle N adapter, 0.5 dB loss DC injector, 0.2 dB loss Isolator, 0.8 dB loss Filter, 2 dB loss RF branching loss Transmit only attenuator pad Flex jumpers Standby switches

Enter any miscellaneous transmitter gains (after cable loss)   dB     -- Examples -- Tower top linear RF power amplifier, 20 dB gain

Enter any miscellaneous transmitter path losses3   dB     -- Examples -- Tree absorption, 0.15-0.4 dB/meter @ 1 GHz Tree absorption, 0.25-0.5 dB/meter @ 2.4 GHz Tree absorption, 0.4-0.6 dB/meter @ 3.3 GHz Tree absorption, 0.5-1.5 dB/meter @ 5.8 GHz Tree absorption, 1.0-2.0 dB/meter @ 10 GHz Slight antenna mis-alignment loss, 0.5 dB Orthogonal (90°) antenna polarization mismatch, 20 dB 75° antenna polarization mismatch, 12 dB 60° antenna polarization mismatch, 6 dB 45° antenna polarization mismatch, 3 dB 30° antenna polarization mismatch, 1.3 dB 15° antenna polarization mismatch, 0.3 dB Linear to circular antenna polarization mismatch, 3 dB Knife edge diffraction

Receiver Side Cable & Antenna Specifications

Enter the receiver's site name

Choose the receiver's external cable type   Times Microwave LMR-400 Times Microwave LMR-400 UltraFlex Times Microwave LMR-500 Times Microwave LMR-600 Times Microwave LMR-900 Times Microwave LMR-1200 Times Microwave LMR-1700 Andrew Heliax LDF4-50A Andrew Heliax LDF5-50A Andrew Heliax LDF6-50A Andrew Heliax LDF7-50A Belden 9913 (RG-8) Belden 8267 (RG-213) Belden 9258 (RG-8X) Belden 8240 (RG-58) Crap RG-8 Other

If Other, enter the receiver's cable loss specification   dB      per 100 meters    per 100 feet

Enter the receiver's external cable length   meters feet

Enter the receiver's antenna peak gain   dBi dBd

Enter receiver's antenna radome loss1   dB

Enter the receiver's site ground elevation (AMSL)   meters feet

Enter the receiver's antenna center-of-radiation height (AGL)2   meters feet

The following four questions are for vertical space diversity systems only.

Enter receiver's vertical diversity antenna center-of-radiation height (AGL)²   meters feet

Enter the receiver's diversity antenna peak gain   dBi dBd

Enter the receiver's diversity antenna external cable length⁴   meters feet

Enter any miscellaneous receiver diversity antenna losses   dB     -- Examples -- Radome loss, 0.5 dB Connector loss, 0.25 dB PolyPhaser, 0.2 dB loss Right angle N adapter, 0.5 dB loss Filter, 2 dB loss Flex jumpers

Total number of receiver cable connectors and/or adapters

Enter any miscellaneous receiver cable losses   dB     -- Examples -- 2-port splitter, 3.5 dB loss 4-port splitter, 6.5 dB loss PolyPhaser, 0.2 dB loss Right angle N adapter, 0.5 dB loss DC injector, 0.2 dB loss Isolator, 0.8 dB loss Filter, 2 dB loss RF branching loss Flex jumpers Standby switches

Enter any miscellaneous receiver gains (before cable loss)   dB     -- Examples -- Tower top receive pre-amplifier, 17 dB gain

Enter the receiver's threshold (sensitivity)   dBm microvolts

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   0.25 : Mountainous, very rough, very dry but non-reflective 1 : Average terrain, with some roughness 2 : Great lakes area 4 : Very smooth terrain, over water or flat desert, non-coastal 6 : Very smooth terrain, over water or flat desert, coastal

If Yes, answer the following two questions.

Enter the average terrain roughness (deviation of elevations)⁸   meters feet

Choose the local area humidity type   Coastal, very humid areas Non-coastal, humid areas Average or temperate areas Dry areas

Enter the average annual temperature   celsius fahrenheit

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        -- Examples -- 5/12 = 0.42 1/2 = 0.50 2/3 = 0.67 1.0 7/6 = 1.17 4/3 = 1.33 5/3 = 1.67 2.0 4.0

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   0.3 0.4 0.5 0.7 0.8 0.9 1 2 3 4 5 6 7 8 9

Would you like to calculate the path distance based on latitude & longitude?   Yes   No

If No, enter the distance between antenna sites   kilometers miles

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