Microstrip Array Antenna

An equivalent network for rectangular shaped microstrip radiating elements is derived. In order to simplify the problem the radiating elements are considered as two slots separated by a transmission line of low characteristic impedance. The slots are characterized by their equivalent admittances. The radiation conductance is derived and found to be proportional to the width for wide strips and to the square of the width for narrower strips. The equivalent susceptance, due to end effects, is represented by a capacitor. The narrow bandwidth of the microstrip radiating elements is due to the high impedance ratio between the slot and the strip. Finally, the network model is used to design a dual polarized planar array.