Investigations On Millimeter-Wave Conformal And Beamformed Antenna

With the technical update of wireless communication systems, demands in communication capacity and transmission rate continue to increase. A lot of attention has been paid to millimeter-wave band which has much richer frequency resources. In the millimeter-wave band, SIW technology combines the characteristics of microstrip and waveguide and has advantages of low profile, low loss, high quality factor, high planar-circuit integration capability, high processing precision, and technical maturity. Based on SIW technology, concerning Chinese millimeter-wave wireless communication standard Q-LinkPan for both short and long distance, this thesis investigates the beamforming technology of Q-band planar and cylindrical conformal antennas, and proposes a novel efficient design method. The thesis is arranged as follows:In the first chapter, background of the investigations is elaborated and relevant researches on the millimeter-wave conformal and beamformed antennas are summarized and reviewed.In the second chapter, an efficient design method of pattern synthesis is proposed, which contains the genetic algorithm and aggressive space mapping method. At first, the genetic algorithm is utilized in a quick search for the optimal excitation of the synthesized array pattern, and then the aggressive space mapping method is applied to map the optimal excitation to a full-wave simulation model. By establishing a relationship of parameter extraction and mapping between full-wave simulation and circuit simulation, antenna design can be accurately accomplished through only a few times of full-wave simulations in a short period of time. This method not only saves computation resources and design time, but also takes mutual couplings among array elements into consideration.In the third chapter, a conformal SIW slot array antenna with high spatial angular selectivity flat-topped beam is designed. In millimeter-wave band, employing the hybrid optimization method introduced in the second chapter for antenna design, the pattern is synthesized to a flat top beam with high spatial angular selectivity. The radiation beam shape is designed to fit the response of an elliptic filter with high spatial angular selectivity and the flat top has small ripples and coverage of ± 30 degree. The fabricated array antenna finds its good performance in the measurement. The research achievement is published in IEEE Antennas and Wireless Propagation Letters.In the fourth chapter, a millimeter-wave planar SIW slot array antenna with cosecant squared beam is designed. By synthesizing the E-plane pattern of the planar slot array and utilizing the hybrid optimization method in the second chapter to optimize both amplitudes and phases of the element excitations, the antenna design is accomplished through only three times of full-wave simulations. The desired pattern shape is achieved with cosecant squared pattern covering up to 40 degree and small fluctuation. The measurement results validate the design target of the cosecant squared beam. The research achievement has been submitted to IEEE Antennas and Wireless Propagation Letters.In the fifth chapter, investigations of this thesis are summarized and some suggestions on future works are given.