Zhang, Y., J. A. Ruiz-Cruz, and K. A. Zaki,  "Ridge Waveguide Coupled Stripline Resonator Filters and Multiplexers",  2006 IEEE MTT-S International Microwave Symposium Digest, pp. 681-684, June, 2006.

Zhang, Y., J. A. Ruiz-Cruz, and K. A. Zaki,  "Ridge Waveguide Divider Junctions for Wide-Band Multiplexer Applications",  2006 IEEE MTT-S International Microwave Symposium Digest, pp. 1225-1228, June, 2006.

Ruiz-Cruz, J. A., Y. Zhang, M. M. Fahmi, and K. A. Zaki,  "Ridge Waveguide Elliptic Filters in Narrow-Wall Canonical Configuration",  Proc. 36th European Microwave Conference, pp. 1080-1082, Sept., 2006.

Ruiz-Cruz, J. A., Y. Zhang, K. A. Zaki, A. J. Piloto, and J. M. Rebollar,  "Ridge waveguide branch-line directional couplers for wideband applications and LTCC technology",  2005 IEEE MTT-S International Microwave Symposium Digest, pp. 1219-1222, June, 2005.