In the present work a design of wideband microstrip patch antennas have been investigated. These antennas were designed to operate in the Sband.Different techniques were followed in order to satisfy this
aim; Single solid patch,single slotted patch, stacked, and stacked shorted configurations printed on thick substrate with rather high permittivity (ε=4.45). Two types of feeding have been applied; direct coaxial probe) feed and indirect (capacitive) feed. r Based on the cavity and aperture models, a general method for the analysis of microstrip patch antenna(MPA), for any mode, fed by coaxial probe was introduced.
The performance of the radiation pattern for MPA operating at TM mode(having narrow main lobe), encourage us to study this mode extensively. This study was focused on eliminate the presence of the side lobes that appeared in the H-plane.The effect of feed location on eliminates the unwanted modes and keeping only the presence of the wanted one have been studied extensively using the MOP and compared with results obtained by using cavity formulations. For the design of the antennas a simulation tool Microwave-Office Package (MOP) was used.In the presented work several techniques for bandwidth (BW) enhancement using the MOP have been investigated:• Bandwidth improvement for single thick rectangular MPA operating at TM mode with two types of feeding (direct and capacitive feeding techniques) has been investigated. The maximum bandwidth produced is 2.6% for direct and 22.6% for indirect feeding excitation techniques.• Bandwidth enhancement using stacking structure with three configurations has been investigated. In the first (thin substrate) and second (thick substrate) configurations, an air gap is filled the spacing between the upper and the lower patches. The maximum bandwidth achieved is 3.5% for the first configuration and 11% for the second one with uniform radiation field pattern. In the third configuration, the lower and the upper patches are square. The bandwidth obtained from this structure is 16% with non uniform radiation field pattern.• Another technique for bandwidth enhancement is presented here. It is based on inductance compensation picture by introducing a capacitor in the antenna structure. This picture is based on cutting a slot in the radiating patch. The maximum bandwidth can be achieved from this design is 27.75% for VSWR≤2 with 14.08dB gain.
• Then another picture of inductance compensation has been combined with the former one in order to increase the bandwidth further. This second picture is based on feeding the slotted radiating patch
capacitively. The bandwidth achieved from this combination can be reached 85% for VSWR≤2 and gain of 11.07 dB with uniform radiation field pattern.
• The stacking configuration with the slotted patch as feeding (lower) patch with direct and indirect feeding techniques has been examined.The maximum bandwidth achieved from direct feed stacking
configuration is 27.7% while that produced from capacitively-fed stacking configuration is 56.7% for VSWR≤2.
• The stacking configuration presented above has been modified by using short walls also with two types of feedings. The maximum bandwidth achieved from direct feed stacking shorted configuration is 30.6% while that produced from capacitively-fed stacking shorted configuration is 67.7% for VSWR≤2.
