Design and characterization of single and multiple beam MM-wave circularly polarized substrate lens antennas for wireless communications

We present the design of single and multiple beam circularly polarized (CP) substrate lens antennas for wireless applications at 30 GHz. Circular polarization and high directivity are desirable features as they can effectively reduce multipath effects and maintain a proper link margin. In addition, multiple beam antennas can be utilized either for space division multiple access (SDMA) or for incorporating "smart" antenna features. The approach taken is to use an aperture coupled patch antenna as the lens feed in combination with low-cost plastic materials for making the lens. For the single-beam design, an ellipsoidal lens is utilized which leads to diffraction limited patterns on-axis. For the multiple-beam design, we choose a hexagonal arrangement of printed patch elements at the back of the lens to maximize scan coverage. Also, the extension length of the ellipsoidal lens is optimized to launch beams with roughly equal power densities.