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Features – Evaluate Clearance

Producing a Path Profile with Herald Pro

Radio line of sight differs from visual line of sight and is dependent on the refractivity of the atmosphere along the path.  Refractivity changes during the day and throughout the year due to humidity, temperature, and atmospheric pressure.  In a typical standard atmosphere the radio ray is bent downward due to refraction at a lower rate than the curvature of the earth.  The effect of this is that the radio ray is received over the visual horizon due to the refraction i.e. radio line of sight is longer than visual line of sight.

The relationship of radio line of sight to visual line of sight in a standard atmosphere is 4/3 or 1.33 and the relationship has been named K-Factor to represent the curvature of the radio wave in any atmosphere.  K-Factor varies along the radio path and the combined variations make up the total path K-Factor.

Clearance along a radio path must consider the statistical max and min K-Factors during the year when designing to a performance standard. Download the FREE Point to Point Radio Link design E-Book from this site to learn more.

1. Evaluate Clearance

Evaluate Clearance

Herald Pro will determine clearance based on climate, frequency, path length, and path profile.  The result will be a plot of the path profile indicating obstruction loss.


Herald provides additional functions to optimise the antenna heights, calculate obstruction loss, identify reflections, optimise space diversity separation, and add additional obstructions based on local knowledge, path surveys, or other data.