Micromachined CPW-fed suspended patch antenna with high gain and broad bandwidth at millimeter wave

Abstract

In this works, novel coplanar waveguide-fed suspended patch antennas at millimeter wave, especially at 60GHz, 77GHz, and 94GHz frequencies, were proposed. The proposed antennas allow the simultaneous optimization of the radiating patch and the feed line on a single substrate. In general, to achieve high performance of antenna, antenna structures are designed in low dielectric constant materials while the circuitry remains on the high dielectric constant regions. Based on this concept, patch antennas are designed to suspend 200μm from the coplanar waveguide which could lie on the high dielectric constant substrate. Because the antenna is supporting in the air with supporting post, high gain and broad bandwidth characteristic is shown. Also, 2ⅹ1 patch array antenna without λ/4 impedance transformer and 2ⅹ2 patch array antenna with λ/4 impedance transformer were designed. For obtaining high performance of patch antenna, the surface micromachining technology consisting of thick photoresist lithography and copper electroplating process is used. Fabricated single patch antenna sizes are 2.2mmⅹ2.2mm and 1.1mmⅹ2.1mm at 60GHz, 1.7mmⅹ1.7mm at 77GHz, and 1.5mmⅹ1.5mm at 94GHz respectively. The size of 2ⅹ2 array antenna for 60GHz, the biggest one, is about 5mmⅹ5.5mm. The measured -10dB bandwidths for single patch antennas and 2ⅹ1 array antennas are in the range of from 9.1% to 19.6% and from 13.1% to 25.2% respectively. Other parameters which represent antenna performance such as field pattern could not be measured. Therefore, simulation results for other parameters are involved in this thesis. Simulated gains are distributed from 5.55dB to 8.3dB for single patch antenna, from 5.62dB to 10.9dB for 2ⅹ1 array antenna, and from 7dB to 12.14dB for 2ⅹ2 array antenna respectively. The simulated total efficiencies are in the range of from 86.7% to 97.4% for all fabricated antennas. Finally, because the proposed antenna allows the integration with MMICs, it can be applied for the...