A Radiospurs Propagation Tools Site

A collection of items that can ease life in putting your studio link together. These are helper calculations that you may wish to do before settling on a route, parameters.

The Great Circle Distance

Choose two points on the globe and the great circle distance is calculated

Great Circle

The Line of Sight

Unfortunately the flat earth freeks are NOT correct, otherwise there would be no problem with designing studio links (STL). Since we are standing (or sitting...) on a globe the line of sight depends upon factors like how tall the antennae are, terrain height amongst other things. Here is a simple calculator of the line of sight form a TX.

Line of Site

The Fresnel Zones

A Fresnel zone, named after physicist Augustin-Jean Fresnel, is one of a series of confocal prolate ellipsoidal regions of space between and around a transmitter and a receiver. Viewing the fresnel zones helps in detecting possible aberrant transmitters, obstructions, terrain mishaps, that could interfere with the primary line of sight transmission. This is because multiple waves could arrive at the RX causing interference. Of cause the fresnel zone is not gpoing to predict the extent of any multi-path interference.

Fresnel Zone

Resistive PADs

Sometimes there is that awkward situstion of just hving too much power (voltage) at a receiver or monitor point, audio tap. Thus a pad may be required. Here is a set of simple calulators for pad design and dissipation.


The Weather

In order to avoid going up the mast when a storm is pending (rain, lightning, tornado), I give a simple weather chart.

Weather up there


Those coaxial cable aen't half lossy. So why not use a waveguide (very low loss above evanescent)

Waveguide types