| In this thesis, three types of integrated lens antenna systems have been investigated for millimeter-wave (mm-wave) applications, namely the ellipsoidal lens, the lens-fed lens/reflector and the spherical lens. First, single and multiple beam circularly polarized ellipsoidal substrate lens antennas are designed, implemented using Rexolite and experimentally characterized at 30 GHz. The designed ellipsoidal lens antenna is capable of launching 31 beams with a 3 dB overlapping level and achieves a scan coverage of 45.4° based on a hexagonal arrangement of printed feed patch elements at the back of the lens. On the other hand, the lens-fed lens/reflector is introduced to reduce the overall weight. In this case, a small feed lens is utilized to feed a larger but thin objective lens or a reflector. On- and off-axis properties are theoretically investigated and experimentally verified at 30 GHz to compare with the single ellipsoidal lens and some important conclusions are drawn. The developed lens antennas are well suited for mm-wave broadband point-to-point or point-to-multipoint wireless communications.; Next, a homogenous spherical lens antenna is presented which is capable of generating multiple beams with very wide scan-angle (up to 180°) and is suitable for low-cost mm-wave automobile collision-avoidance applications. A detailed efficiency analysis is carried out and the corresponding focusing properties are studied for some low-loss materials available for use at mm-wave frequencies. In addition, suggestions are made on how to reduce the spherical aberrations by choosing appropriate feed sources. The theory is experimentally verified at 77 GHz using a Teflon spherical lens fed with printed tapered slot antennas. |
