A new broadband circularly polarized (CP) square slot antenna is evaluated numerically and verified experimentally. The proposed antenna uses a lightening-shaped feedline protruded from the signal line of the feeding coplanar waveguide (CPW). Two symmetrical F-shaped slits embedded in opposite corners of ground plane are designed to obtain an excellent CP bandwidth. By adjusting the dimensions of the lightening-shaped feedline, the CP bandwidth can be further enhanced. Measured results show that the 3-dB axial-ratio bandwidth of the proposed antenna can reach 51.7% (2150 MHz-3650 MHz), and the impedance bandwidth is as large as 60.2% (2150 MHz--4000 MHz) with VSWR ≤ 2. Measured results are in good agreement with the simulation. The proposed antenna can be easily fabricated because of the simple coplanar geometry.
2. Xu, R. P., X. D. Huang, and C. H. Cheng, "Broadband circularly polarized wide-slot antenna," Microwave Opt. Technol. Lett., Vol. 49, 1005-1007, May 2007.
3. Tseng, L. Y. and T. Y. Han, "Microstrip-fed circular slot antenna for circular polarization," Microwave Opt. Technol. Lett., Vol. 50, 1056-1058, Apr. 2008.
4. Shi, S., K. Hirasawa, and Z. N. Chen, "Circularly polarized rectangularly bent slot antennas backed by a rectangular cavity," IEEE Trans. Antennas Propag., Vol. 49, No. 11, 1517-1524, Nov. 2001.
5. Qing, X. M. and Y. W. M. Chia, "Broadband circularly polarized slot loop antenna fed by three-stub hybrid coupler," Electron. Lett., Vol. 35, 1210-1211, Jul. 1999.
6. Chu, Q. X. and S. Du, "A cpw-fed broadband circularly polarized square slot antenna," Microwave Opt. Technol. Lett., Vol. 52, No. 2, 409-412, Feb. 2010.
7. Chou, C. C., K. H. Lin, and H. L. Su, "Broadband circularly polarized cross-patch-loaded square slot antenna," Electron Lett., Vol. 43, 485-486, 2007.
8. Iwasaki, H., "A circularly polarized small-size microstrip antenna with a cross slit," Electron Lett., Vol. 44, 1399-1401, 1996.
9. Sze, J. Y., K. L.Wong, and C. C. Huang, "Coplanar waveguide-fed square slot antenna for broadband circularly polarized radiation," IEEE Trans Antennas Propag., Vol. 51, No. 8, 2141-2144, Aug. 2003.
10. Sze, J. Y. and C. C. Chang, "Circularly polarized square slot antenna with a pair of inverted-L grounded strips," IEEE Trans Antennas and Wireless Propagation Lett., Vol. 7, 149-151, 2008.
11. Sun, J. Y., C I. G. Hsu, Z. W. Chen, and C. C. Chang, "Broadband CPW-fed circularly polarized square slot antenna with lightening-shaped feedline and inverted-L grounded strips," IEEE Trans. Antennas Propag., Vol. 58, 973-977, Mar. 2010.
12. Wang, C. J. and C. H. Chen, "CPW-fed stair-shaped slot antennas with circular polarization," IEEE Trans. Antennas Propag., Vol. 57, No. 8, 2483-2486, Aug. 2009.