Integrated antennas on organic packages and cavity filters for millimeter-wave and microwave communications systems
Amadjikpe, Arnaud Lucres
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Driven by the ever growing consumer wireless electronics market and the need for higher speed communications, the 60-GHz technology gifted with an unlicensed 9 GHz frequency band in the millimeter-wave spectrum has emerged as the next-generation Wi-Fi for short-range wireless communications. High-performance, cost-effective, and small form-factor 60-GHz antenna systems for portable devices are key enablers of this technology. This work presents various antenna architectures built on low-cost organic packages. Planar end-fire switched beam antenna modules that can easily conform to various surfaces inside a wireless device platform are developed. The planar antenna package is realized on thin flexible LCP dielectrics. One design is based on a planar Yagi-Uda antenna element and the second on a tapered slot antenna element. A low-loss microstrip-to-slot via transition is designed to provide wide impedance matching for end-fire antenna paradigms. The novel transition utilizes the slow-wave concept to provide unbalanced to balanced mode conversion as well as impedance matching. It is demonstrated that the planar antenna packages may be even integrated with active circuits that are cavity recessed inside the thin dielectric. A compact switched-beam antenna module is demonstrated. The first-ever integrated mm-wave active antenna module on organic package capable of generating both broadside and end-fire radiation is also developed in this work. Both broadside and end-fire radiators are co-designed and integrated into a single multilayer package to achieve optimal directivity, efficiency and frequency bandwidth and yet maintain excellent isolation between the two radiators. Post-wall cavities, image theory and dielectric slab modes concepts are invoked to optimize these functions. Active circuitry are integrated into the same package to add control functions such as beam switching, and also amplify the packaged-antenna gain when operated either as a transmitter or a receiver. A significant challenge in the design of antenna systems for wireless platforms is the assessment of embedded antenna performance, that is, the proximity effects of the platform chassis on the embedded antenna. Various antennas are mounted at different locations inside a laptop computer chassis: modeling and experimental studies are carried out to characterize this problem that is apparent to an antenna behind a radome. Air traffic control radars usually require cavity filters that can handle high power and low in-band insertion loss while providing enough out-band rejection to prevent interference with neighboring channels. Such radars that operate in the S-band consist of filter banks frequency micro electromechanical systems (RF-MEMS) switches. Evanescent-mode mode cavity resonators are loaded with RF-MEMS tuning capacitance networks to control the resonant frequency of a second-order bandpass filter. The second part is the design of a novel cavity filter architecture for enhanced selectivity near the passband. It is a second-order folded cavity resonator bandpass filter with magnetic source-load cross coupling. This filter can have at least two finite transmission zeros near the passband.