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A Q-band injection-locked frequency divider with inductive feedback for a locking range enhancement, IEEE Microwave Wireless Compon Lett 21 (2011), 317-319. 2. Y.-T. Chen, M.-W. Li, and T.-H. Huang, A V-band CMOS direct injection-locked frequency divider using forward body bias technology, IEEE Microwave Wireless Compon Lett 20 (2010), 396-398. 3. T.-N. Luo and Y.-J.E. Chen, A 0.8-mW 55-GHz dual-injection locked CMOS frequency divider, IEEE Trans Microwave Theory Tech 56 (2008), 620-625. 4. A. Katz, O. Degani, and E. Socher, Modeling and design of a lowpower injection-locked frequency divider in 90nm CMOS for 60GHz A 60-GHz 0.13-lm CMOS divide-by-three frequency divider, IEEE Microwave Theory Tech 56 (2008), 2409-2415. 7. Y. Chao and H.C. Luong, Analysis and design of a 2.9-mW 53.4-79.4-GHz frequency-tracking injection-locked frequency divider in 65-nm CMOS, IEEE J Solid-State Circuits 48 (2013), 2403-2418.ABSTRACT: Aperture-coupled cylindrical dielectric resonator antennas (DRAs) fed by a microstrip line are investigated by varying their aspect ratio and permittivity to maximize their impedance bandwidth, while maintaining an acceptable radiation pattern. Although the maximum impedance bandwidth attainable by an aperture-coupled DRA is comparable to that of a probe-fed one (40% vs. 45%), the maximum combined bandwidth (which also accounts for the pattern shape) is smaller-about 30% versus 45%. The study reveals a very important conclusion: while a probe feed is good for obtaining broadband DRAs that are tall or pencil-like, an aperture-coupled feed is more suitable for applications that require low-profile or pancake-like broadband DRAs.

Three designs for cylindrical dielectric resonator antennas (DRAs) are presented that have little lateral radiation. The three designs have different combinations of aspect ratio and permittivity depending on the feed arrangement: the TM 121 mode is used for an aperture-coupled feed and a hybrid probe-DRA mode is used for probe-fed and dual probe-fed variations. These proposed antennas reduce mutual coupling between array elements as well as mitigate the impact of edge diffraction on the radiation patterns when mounted on finite ground planes.

A reduced-lateral-wave cylindrical dielectric resonator antenna (DRA) is presented, which produces very little lateral radiation at the horizon. The design technique centers on finding an optimal aspect ratio of height to radius for the DRA to minimize the lateral radiation. The lateral radiation of the DRA is reduced by operating in the higher-order TM 1 21 mode. The tradeoff is a reduced bandwidth, relative to the usual TM 11 0 mode. Numerical results are obtained from both HFSS and CST Microwave Studio simulations.