Microstrip Franklin array

Image of the Microstrip Franklin array antenna.

The Microstrip Franklin array effectively consists of thin rectangular half-wavelength patches which are connected with non-radiating, phase reversing phasing lines. The phasing lines are narrow half-wavelength microstrip lines folded into quarter-wave stubs so that the counteracting standing wave currents do not radiate. The natural current distribution is thus converted into a co-phased distribution of currents which produce only one major radiation pattern.

The synthesis algorithm in Antenna Magus can design this antenna for gain or number of elements, as well as designing the array on a wide variety of substrates. It has a narrow broadside beam with very narrow impedance bandwidth (1%) and typical gain between 7 and 20 dBi (depending on the number of elements).

The advantage of the Franklin array is that it requires no feed network and is ideal for low-cost point to point communication.

Total 3D gain of 6 element Franklin array.