Research On Waveguide Slot Antenna Array And Power Combing Waveguide Lens Antenna

The waveguide slot antenna arrays have been widely used in radar, communication systems, and navigation applications for their geometric simplicity, efficiency, polarization purity, conformal installation and power capability. And for the high power millimeter-wave systems, the research on quasi-optical combining has been a hot area. Therefore, this dissertation focuses on the design methods of microwave and millimeter-wave waveguide slot arrays and the millimeter-wave power combiner using quasi-optical techniques based on the waveguide lens antenna with detailed considerations as follows.(1) An approximate expression is presented to compute field distribution of the waveguide slot by using MoM (method of moments). The error of this expression is about 2%. Two design equations are deduced by using the expression based on the field analysis method. And then an improved Elliott's design method for waveguide slot arrays is proposed. Consequently the design efficiency is significantly improved. The improved method is used to design a low side lobe slot array operating at 9.375 GHz. Good agreements between the simulated results and the measured ones are obtained.(2) A kind of dielectric-loaded waveguide slot array which can be easily and finely fabricated by the printed circuit board (PCB) process is developed at microwave and millimeter-wave frequencies. An approximation model is given. And the design equations are derived based on the Elliott's design equations. To verify the design method, an 8-element waveguide slot array operating at 17.4 GHz is simulated, fabricated and tested. The measurement agrees well with the theoretical prediction.(3) A new kind of method is presented for designing large waveguide slot array based on the field analysis design method and the theory of transmission line. The coupling between the slots which located on different waveguides is highly reduced by the conductance strips loading. The design process takes less computation and time. At last an 8×8 slots array operating at 9.0 GHz is designed, fabricated and tested. The measurement results show a good performance of the slot array and the design method.(4) A new kind of wideband waveguide slot array for SAR is presented. Elliptical slot is first used for the designing of the waveguide slot antenna. An analytical expression is presented to compute the normal conductance of the waveguide elliptical slot based on that of the conventional one. And a design procedure is given by using the theory of transmission line and the software of HFSS. At last an 8-element waveguide slot array operating at X-band is designed and measured. The predicted results are compared with measured data and good agreement is achieved.(5) A 2D waveguide lens is designed by using different parallel-plate waveguides propagating the TE10 mode. And the effective refractive index of the waveguide lens is given. Then two-dimensional waveguide thin lenses, hyperbolic waveguide lens and Meniscus waveguide lens, are presented for millimeter-wave quasi-optical power combining based on the waveguide lens antenna. The proposed power combiners have higher efficiency than those of the one using substrate, because the waveguide lenses are free of dielectric loss. Furthermore it is also easy to fabricate. Finally, a ten-way power combiner using waveguide Meniscus thin lens is designed and measured at 30GHz. Good agreement is obtained between the simulated results and the measured ones.