Miniaturization of aperture-coupled patch antennas through metasurface inspired defected ground structure

The purpose of this thesis is to design a compact microstrip patch antenna for cubesat applications. Aperture coupled fed microstrip patch antenna (ACMA) has been preferred as a design. First of all, the effect of the dielectric constant of ACMA's patch and feed substrates on miniaturization and ACMA radiation performance was examined. For this, the following four antenna were designed at 8.0 GHz frequency using materials with different dielectric coefficients in the CST Microwave Studio program; FR4-FR4, RT5880-RT5880, RT5880-RO3010, RO4360-RO3010. It is observed that the smallest size is obtained with the substrate with the highest dielectric constant and the performance is better when the dielectric constant difference between the layers is high. In the next stage, an attempt was made to reduce the antenna operating frequency to lower frequencies (below 6.0 GHz) by adding a metasurface-inspired defective ground structure to the ground plane of ACMAs designed at 8.0 GHz operating frequency. Thaks to this method, the operating frequency of the RO4360-RO3010 antenna decreased from 7,954 GHz to 5,64 GHz, meaning a 30% reduction was achieved depending on the frequency. The operating frequency of the FR4-FR4 antenna decreased from 8,031 GHz to 5,095 GHz, meaning a 36% reduction was achieved depending on the frequency. In addition, a conventional FR4-FR4 antenna at 5.1 GHz frequency was designed and compared with the miniaturized FR4-FR4 antenna. While the space covered by the conventional antenna is 1890 mm2, the space covered by the miniature antenna is 622 mm2. This corresponds to a reduction of approximately 67%. As a result, while the value of the conventional antenna was 30% better in terms of gain, it was seen that the bandwidth was higher in the miniaturized antenna. In addition, in this thesis study, the miniaturized FR4-FR4 antenna was produced and it was shown that the measurement results of the S11 parameters and the simulation results were compatible.