1. Padros, N., J. Ortigosa, J. Baker, M. Iskander, and B. Thomberg, "Comparative study of high-performance GPS receiving antenna design," IEEE Trans. Antennas and Propagation, Vol. 45, No. 4, 698-706, 1997.
doi:10.1109/8.564096
2. Heidari, A. A., M. Heyrani, and M. Nakhkash, "A dual-band circularly polarized stub loaded microstrip patch antenna for GPS applications," Progress In Electromagnetics Research, Vol. 92, 195-208, 2009.
doi:10.2528/PIER09032401
3. Zhou, Y., C.-C. Chen, and J. L. Volakis, "Dual band proximity-fed stacked patch antenna for tri-band GPS applications," IEEE Trans. Antennas and Propagation, Vol. 55, No. 1, 220-223, Jan. 2007.
doi:10.1109/TAP.2006.888476
4. Hsieh, W.-T., T.-H. Chang, and J.-F. Kiang, "Dual-band circularly polarized cavity-backed annular slot antenna for GPS receiver," IEEE Trans. Antennas and Propagation, Vol. 60, No. 4, 2076-2080, Apr. 2012.
doi:10.1109/TAP.2012.2186229
5. Chen, S., G. Liu, X. Chen, T. Lin, X. Liu, and Z. Duan, "Compact dual-band GPS microstrip antenna using multilayer LTCC substrate," IEEE Antennas and Wireless Propagation Letters, Vol. 9, 421-423, 2010.
doi:10.1109/LAWP.2010.2049822
6. Wang, Y., J. Feng, J. Cui, and X. Yang, "A dual-band circularly polarized stacked microstrip antenna with single-fed for GPS applications," Antenna, Propagation and EM Theory, ISAPE 2008, 108-110, 2008.
doi:10.1109/ISAPE.2008.4735151
7. Beddeleem, G., J. M. Ribero, G. Kossiavas, R. Staraj, and E. Fond, "Dual-frequency antenna circularly polarized for GPS-SDARS operation," Antennas and Propagation, EuCAP 2007, 1-5, 2007.
8. Huang, J., "Circularly polarized conical patterns from circular microstrip antennas," IEEE Trans. Antennas and Propagation, Vol. 32, No. 9, 991-994, Sep. 1984.
doi:10.1109/TAP.1984.1143455
9. Chiu, L. and Q. Xue, "Investigation of a wideband 90° hybrid coupler with an arbitrary coupling level," IEEE Trans. Microwave Theory and Techniques, Vol. 58, No. 4, 1022-1029, Apr. 2010.
doi:10.1109/TMTT.2010.2042835
10. Gipprich, J. W., "A new class of branch-line directional couplers," IEEE MTT-S International Microwave Symposium Digest, Vol. 2, 589-592, 1993.
doi:10.1109/MWSYM.1993.276869
11. Tanaka, H., N. Babba, S. Arai, and T. Nishikawa, "2 GHz one octave-band 90 degree hybrid coupler using coupled meander line optimized by 3-D FEM," IEEE MTT-S International Microwave Symposium Digest, Vol. 2, 903-906, 1994.
12. Eom, S. Y. and H. K. Park, "New switch=network phase shifter with broadband characteristics," Microwave Optical Technology Letter, 255-257, 2003.
doi:10.1002/mop.11030