Microwave/millimeter wave via-only bandpass filters for LTCC applications

Abstract

higher than 38.5 dB; and in the operating bandwidth 8.8 -9.8 GHz, the measured isolation is better than 40.5 dB. Figure 5 shows the measured and simulated E-plane and Hplane radiation patterns for port-V excitation only. The crosspolarization levels in both the E-plane and H-plane are about Ϫ30 dB in the main beam region at 9.3 GHz; for all the patterns observed (including the patterns for port H), the measured patterns are stable in the operating-frequency band and the cross-polarization levels are less than Ϫ28.5 dB. CONCLUSIONA dual-polarized stacked-microstrip patch antenna excited by both open-ended and T-shaped microstrip lines through two H-shaped slots has been studied. The antenna achieved wide high isolation (better than 40.5 dB), low cross-polarization levels (less than Ϫ28.5 dB), and stable radiation patterns, as well as broad VSWR Յ 2 bandwidths (20.7% at port V and 19.1% at port H). This antenna is suitable as an array element for spaceborne synthetic aperture radar (SAR) and active phased-radar applications. MICROWAVE/MILLIMETER WAVE VIA-ONLY BANDPASS FILTERS FOR LTCC APPLICATIONS