Impedance matching of electrically small patch antennas on Cubesats in the s-band

Abstract

Antennas are important components in radio frequency (RF) communication systems to convert electrical signals to electromagnetic (EM) waves, which are radiated into free space. In these modern times, electronic designers are working towards the miniaturisation of electronic hardware. CubeSat communication system components, such as patch antennas, are no exception. Electrically-small antennas are difficult to impedance match and to achieve acceptable performance characteristics. The motivation for carrying out the research and an introduction into the communication system onboard a typical CubeSat is presented. The objectives and research methodology, which were implemented to design and impedance match an electrically-small patch antenna are then presented. An in-depth investigation into the theory of microstrip patch antennas is presented followed by passive and non-Foster impedance matching techniques. Then the design of electrically-small microstrip patch antennas are presented. Four patch antennas were designed and simulated in Agilent design system (ADS) and FEKO. Both internal and external impedance matching techniques were implemented. Three patch antenna prototypes were built and tested and the measured performance parameters compared to the specifications and simulated results. The lowering of the resonant frequency of a micostrip patch antenna by implenting miniaturisation techniques produced an input return loss of 16.678 dB, a realised gain 2.874 dBi and an axial ratio of 2.351 dB.