Mixed boundary semicircular and 120 degrees-sectoral microstrip antennas

120 degrees -sectoral microstrip antenna and mixed boundary semicircular antennas are analyzed using the Green´s function approach and segmentation methods. The sectoral microstrip antennas with sectoral angles less than 180 degrees can be used to reduce mutual coupling between elements for the same interelement spacing. The mixed boundary microstrip patch antennas appear very promising for building arrays where mutual coupling between elements can be controlled by having various combinations of electric and magnetic walls for elements. The Green´s functions of mixed boundary sectoral elements have been developed using the method of expansion in a series of eigenfunctions. The computed input VSWRs (voltage standing wave ratios) and bandwidths agree well with experimental results. The 120 degrees -sectoral antenna has more bandwidth (3.6%) than the circular antenna (3%) and is smaller in size. The large difference in bandwidths of two mixed boundary semicircular antennas suggests that the straight edges radiate more than the circular edges.<>