Ka-band Microstrip Antenna Design

Microstrip antennas have been used in many applications, such as guidance, radar, satellite communication because of their inherent advantages like light weight, thin profile, easy conformal, flexible design, low cost and conveniently to be integrated with MIC and MMIC circuits. Millimeter-wave(MMW) has the medium wavelength compared to the microwave and IR, so its characteristics are between of them. For example, the MMW has the moderate spatial resolution and penetrability of the smoke or fog, therefore in some cases the MMW can complete the missions which are difficult to the microwave and IR.Ka band is one part of Millimeter-wave band. In this paper, three kinds of Ka band microstrip antennas with the resonant frequency of 35 GHz have been designed. For the needs of the measurement, the waveguide-to-microstrip transition structure has been designed. In each case the antenna is fed by the microstrip line, the end of which is stepped into the waveguide through the slot of the central wide side of waveguide and is used as the excitation of the waveguide.The main work of this paper includes:1) The design and test of Ka band microstrip monopulse antennas. First, a single microstrip antenna with central frequency of 35GHz has been designed with the assistance of Ansoft HFSS 9.0. Feeding method and position selection have been taken into account in this procession. Then a microstrip subarray of 2×2 patch cells and microstrip monopulse comparator network have been simulated. At last, a microstrip subarray of 4×4 patch cells and a monopulse antenna composed by four such subarrays and comparator network have been manufactured and measured.2) The design and simulate of Ka band wideband aperture coupling microstrip antennas. A aperture coupling microstrip antenna with central frequency of 35GHz has been designed with the assistance of Ansoft HFSS 9.0. The simulation results show the wideband characteristic of it. Then the aperture coupling microstrip antenna array has been designed and simulated and the results are analyzed.3) The design and simulate of Ka band wideband microstrip monopole antennas. The circular and elliptical microstrip monopole antennas with central frequency of 35GHz have been designed with the assistance of Ansoft HFSS 9.0. The bandwidth of VSWR<2 is between 26.4GHz and 40GHz which arrives about 40% compared to the typical 5% bandwidth of the conventional microstrip antennas.