| In recent years, phased antenna arrays have gained a wider and wider popularity. Presently, the trend is to increase the efficiency of the phased array systems. In particular, there is a specific need for greater capacities and transmission speeds, which requires the design of higher performance systems. In this context, wideband antennas are required.; Printed and slot microstrip antennas are widely used in phased array systems. They exhibit a low profile, small size, light weight, low cost, high efficiency, and ease of fabrication and installation. Furthermore, they are generally economical to produce because they are readily adaptable to hybrid and monolithic integrated circuits' fabrication techniques at RF and microwave frequencies.; This research presents the design of wideband slot and printed antennas for phased array antenna systems. Three analysis tools are used in this analysis, ADS Momentum, HFSS, and a developed code by the author based on the finite difference time domain (FDTD) method. The FDTD code combines a comprehensive set of features such as: near field and far field excitations with different source types, resistor, capacitor, inductor, thin wire, diode and far field calculations. In addition, it provides two absorbing boundary conditions: Liao and Convolutional Perfect Matched Layer (CPML). The code can also simulate half of a symmetric geometry by utilizing the symmetry properties.; Different types and shapes of antennas are designed: printed and slot antennas, and triangular and rectangular shape antennas. Different techniques are applied to improve the antenna bandwidth and size. Introducing a tapered transition between the feed line and the antenna is found to improve the bandwidth. Also, adding a tuning stub creates new resonances, which can be utilized to improve the bandwidth. Adding a short is utilized to improve the bandwidth for some antenna designs. Using half of one antenna design and flipping it by 90° decreases the antenna size. Using a wide slot improves both bandwidth and size of the antenna. In addition, the parametric study of some antenna designs is performed to improve the bandwidth and size. A re-configuration technique using ideal switches is also investigated to improve the usable bandwidth of the antenna, while maintaining the good radiation characteristics of the antenna.; Different synthesis techniques are studied to reduce the sidelobe level and beamwidth of one-dimensional antenna arrays, where Dolph-Tschebyscheff is found to give the best results. Then, wideband coplanar waveguide and microstrip feed networks are designed to feed one-dimensional arrays of slot and printed antenna designs, respectively, with different scanning angles. Two-dimensional arrays of slot and printed antennas are also designed, and their characteristics are presented and compared. Moreover, arrays are designed and presented for dual- and circularly-polarized applications. |
