RadioMAK Power Density Calculator
2003, 2004 All rights reserved, Updated Oct 11, 2004

Description: This power density calculator is intended for performing rough order of magnitude calculations for line-of-site radio links. (A companion noise estimator is also available to assist with signal-to-noise estimates.) A simple spherical area far-field calculation is used for power density. For receive power, adjustments are made for antenna gain, e.g., to address corresponding receive antenna aperature.
Use: The user enters TX power, TX antenna gain, frequency, distance, RX antenna gain, and RX antenna impedance (replacing default values pre-entered as an example). Clicking "calculate" causes power density (watts per sq ft and per sq meter), and the received antenna dbW and voltage results to be updated.
Notes: If the user wishes to enter TX ERP (rather than power and TX ant gain), merely enter the ERP as the power value, and -2.15 dbD as the TX ant gain (i.e., to convert to isotropic).
If unexpected results are obtained, check data entries for proper units (e.g., dbD vs dbI, MHz vs KHz).
"Disclaimer": Speaking from some familiarity with design assurance level A, the author assures you that no such development / verification or documentation pedigree exists for this calculation page, so the user is cautioned to use results for initial rough estimates only.
A previous version of this calculator (no tx ant entry) is available by clicking here.
Note the links below may be of some value for related estimates as well, e.g., the RadioMAK noise estimator for S/N estimates.

TX Power (W)

TX Ant Gain (dbD)

Frequency (MHz)

Distance (miles)

RX Ant Gain (dbD)

Rx Ant Impedance (ohm)

Result W / sq.ft.

Result W / sq.meter

Result Antenna dbW

Result Antenna Volts

Related Radio MAK Page: Noise Estimator

Related link: Topo Info
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