SMALL-CELL WAVEGUIDE ANTENNA ARRAY FOR E-BAND POINT TO POINT WIRELESS COMMUNICATIONS

In this paper, a highly directive small-cell waveguide antenna array for point to point wireless communication in E-band radio frequency systems is presented. The antenna array is designed and dedicated for the paired bandwidths 71-76 and 81-86 GHz. It is composed of 32 * 32 horn elements with a total surface of ~ 100 * 100 mm (2) to achieve a directivity [greater than or equal to] 38 dB, narrow beam (~ 2[degrees]), and low-level sidelobe [less than or equal to] -26 dB. A compact stepped horn antenna element (SHE) (6.6 mm) is designed. It is 25% smaller than a standard horn element (in the same band) keeping the same aperture surface (3.4 * 3.4 [mm.sup.2]). Layer-by-layer micromachining process is employed for the fabrication. A compact feeding network (25 mm) is realized using ridged waveguide technique with a cut-off frequency of 55 GHz, much lower than standard WG one in the same band. A bow-tie multi-section waveguide polarizer rotator ([+ or -]90[degrees]) is optimized and associated with the WG transitions to re-phase the fields applied to SHE elements. Electric discharge machining (EDM) process was used to manufacture a 4 * 4 sub-array prototype including the entire WG power-feed network. The antenna is characterized in an anechoic chamber, and experimental results are compared to 3-D electromagnetic simulations with good agreements over the two bands.