Compact phased array dimension calculator

On-line compact directional phased array antenna calculator. Unlike most antenna designs on this site which are omni directional, this two element phased antenna type is very directional and compact and has been constructed to facilitate the reception of telemetry signals from the smart falconry telemetry project. Ideal for portable use in the field.

This antenna was designed by the Swiss radio amateur Rudolf Baumgartner, callsign HB9CV, in the late 1950's. It makes use of a phase difference between the two actively fed dipoles (fed 225° out of phase) which makes it possible to achieve a front to back ration of up to 40dB. That is very impressive for a two element antenna.

Enter the required frequency in MHz and the antenna designer will calculate the dimensions of the required elements as shown below.

Notes: Matching this antenna design to a 50 Ohm coaxial feedline requires a capacitor. The gamma match distance is the distance from the feedpoint on the antenna to the capacitor which is 5mm. Best way to determine the value of the capacitor is to use a variable capacitor and an antenna analyzer to get the SWR as low as possible, then replace it with a fixed value capacitor.

For best matching results with 50 Ohm coax, the fed phase element distance from the boom and radiators should be between 2mm to 4mm.