New zeroth-order resonators (ZORs) are utilized as parasitic elements to enhance a microstrip antenna's bandwidth. By utilizing mushroom T/L shaped resonators, extra resonances are generated. Then, by merging the resonances of the microstrip antenna and the T/L shaped resonators, a wideband antenna is obtained to cover the 5.15-5.35 GHz wireless local area network (WLAN) band. As the ZORs are embedded in the patch of the microstrip antenna, the usages of the parasitic elements do not increase the antenna size. Moreover, as one ZOR resonance is lower than the microstrip patch resonance, a compact antenna is realized. The patch size is decreased from 0.27λc×0.42λc×0.027λc of the reference microstrip antenna (RMA) to 0.25λc×0.40λc×0.026λc of the proposed ZOR based microstrip antenna, where λc is the wavelength of their corresponding lower cutoff frequencies. The proposed antenna was fabricated and measured. The simulated and measured -10 dB impedance bands of the proposed antenna are 5.06-5.40 GHz and 5.07-5.42 GHz, respectively. And, its bandwidth increases 70% compared to the RMA. The simulated and measured patterns are stable in the whole operating band. The gains of 4.73 dBi and 4.24 dBi are measured at the ZOR modes, and 7.88 dBi is measured at the microstrip patch mode.
2. Mandal, K. and P. P. Sarka, "High gain wide-band U-shaped patch antennas with modified ground planes," IEEE Trans. Antennas Propag., Vol. 61, No. 4, 2279-2282, 2013.
3. Cao, W. Q. and W. Hong, "Bandwidth and gain enhancement for probe-fed CP microstrip antenna by loading with parasitical patches," Progress In Electromagnetics Research Letters, Vol. 61, 47-53, 2016.
4. Verma, A. K. and Nasimuddin, "Resonance frequency of rectangular microstrip antenna on thick substrate," Electronics Letters, Vol. 37, 1373-1374, 2001.
5. Peng, L., C. L. Ruan, and X. H. Wu, "Design and operation of dual/triple-band asymmetric Mshaped microstrip patch antennas," IEEE Antennas Wireless Propag. Lett., Vol. 9, 1069-1072, 2010.
6. Tiwari, R. N., P. Singh, and B. K. Kanaujia, "Butter fly shape compact microstrip antenna for wideband applications," Progress In Electromagnetics Research Letters, Vol. 69, 45-50, 2017.
7. Peng, L., J. Y. Xie, and S. M. Li, "Wideband microstrip antenna loaded by elliptical rings," Journal of Electromagnetic Waves and Applications, Vol. 30, No. 2, 154-166, 2016.
8. Guha, D., C. Sarkar, and S. Dey, "Wideband high gain antenna realized from simple unloaded single patch," IEEE Trans. Antennas Propag., Vol. 63, No. 10, 4562-4566, 2015.
9. Shetti, N. M., "Waveguide coupled microstrip patch antenna a new approach for broad band antenna," Progress In Electromagnetics Research C, Vol. 72, 73-79, 2017.
10. Yoo, S. and S. Kahng, "CRLH zor antenna of a circular microstrip patch capacitively coupled to a circular shorted ring," Progress In Electromagnetics Research C, Vol. 25, 15-26, 2012.
11. Peng, L., J. Y. Mao, X. F. Li, X. Jiang, and C. L. Ruan, "Bandwidth of microstrip antenna loaded by parasitic zeroth-order resonators," Microwave and Optical Technology Letters, Vol. 59, No. 5, 2017.
12. Ko, S. T. and J. H. Lee, "Wideband folded mushroom zeroth-order resonance antenna," IET Microwaves Antennas & Propagation, Vol. 7, No. 2, 9-84, 2013.
13. Ko, S.-T. and J.-H. Lee, "Hybrid zeroth-order resonance patch antenna with broad-plane beamwidth," IEEE Trans. Antennas Propag., Vol. 61, 19-25, 2013.
14. Mehdipour, A., T. A. Denidni, and A.-R. Sebak, "Multi-band miniaturized antenna loaded by ZOR and CSRR metamaterial structures with monopolar radiation pattern," IEEE Trans. Antennas Propag., Vol. 62, No. 2, 555-563, 2013.
15. Amani, N. and A. Jafargholi, "Zeroth-order and TM modes in one-unit cell CRLH mushroom resonator," IEEE Antennas Wireless Propag. Lett., Vol. 14, 1396-1399, 2015.
16. Udagedara, I., M. Premaratne, I. D. Rukhlenko, H. T. Hattori, and G. P. Agrawal, "Unified perfectly matched layer for finite-difference time-domain modeling of dispersive optical materials," Optics Express, Vol. 17, No. 23, 21179-90, 2009.
17. Szabo, Z., G. H. Park, R. Hedge, and E. P. Li, "A unique extraction of metamaterial parameters based on Kramers-Kronig relationship," IEEE Transactions on Microwave Theory and Techniques, Vol. 58, 2646-2653, 2010.
18. Schneider, V. M. and H. T. Hattori, "High-tolerance power splitting in symmetric triple-mode evolution couplers," IEEE Journal of Quantum Electronics, Vol. 36, No. 8, 923-930, 2000.
19. Kapon, E., J. Katz, and A. Yariv, "Supermode analysis of phase-locked arrays of semiconductor lasers," Optics Letters, Vol. 9, No. 4, 125-127, 1984.
20. Peng, L., J. Y. Xie, X. Jiang, and C. L. Ruan, "Design and analysis of a new ZOR antenna with wide half power beam width (HPBW) characteristic," Frequenz, Vol. 71, No. 1–2, 41-50, 2017.