Experimental study of the characteristics of coupled top-loaded microstrip monopoles

The characteristics of a two-element broadside array consisting of a top-loaded microstrip monopole fed at the center with antiphase currents and a parasitic microstrip element are investigated experimentally. The input impedance is measured as a function of frequency, with spacing between the elements and length of the parasitic element as parameters. Our results show that the coupled system has a dual frequency characteristics. It is also shown that a particular set of values of spacing and parasitic element length leads to a substantial increase in the bandwidth of the lower resonance. The radiation pattern of the array has also been measured.