Experimental investigation of slot type dual spiral antenna fed by a microstrip line

The fundamental radiation characteristics of the slot-type dual spiral in the presence of a plane reflector are described. The testing frequencies used are in the 12-GHz range. It is demonstrated that a single slot-type dual spiral antenna can be fed by a microstrip transmission line, whose tail section is used for impedance matching of the antenna and the transmission line. An array consisting of eight slot-type dual spirals can also be fed by a microstrip transmission line, in the presence of a plane conducting reflector. The unidirectional radiation pattern, axial ratio, and return loss are discussed on the basis of experimental data.<>