This chapter presents a simple, metamaterial-loaded planar ring antenna for WLAN/WiMAX applications. The proposed antenna is equipped with two neutralization lines to improve performance in the desired operating bands. The use of neutralization lines as conducting strip allows the antenna to function at the upper resonance-3.5GHz and the incorporation of complementary split ring resonator at the rear of the substrate benefits in the antenna's compact size. Due to the incorporation of a quarter wave transformer with a semicircular ring construction, the ring antenna produces better dual-band response. The upper resonance 3.5GHz is obtained due to the combination of tuned semicircular ring and circular ring along with the conducting strip in the structure. The fabricated antenna is printed on FR4 substrate with dimensions 10×10×1.6 mm3. The simulated results are verified by experimenting the fabricated antenna. It offered 14.6% bandwidth in the lower resonance 2.4 GHz and 8.5% bandwidth at upper resonant frequency 3.5GHz with radiation characteristics suitable for the WLAN/WiMAX applications.
TopIntroduction
With the growing popularity of sophisticated wireless communication systems, there seems to be a growing interest in lightweight, simple, and cost-effective broadband antennas. (Zaker, R. and A. Abdipour, 2010). For a variety of wireless applications, circularly polarised (CP) antennas have recently received much interest than linearly polarised (LP) aerials. particularly WLAN, WiMAX, Wi-Fi, and Bluetooth (Rocca, P., M. Donelli, G. Oliveri, F. Viani, and A. Massa, 2013). In terms of maximum intensity toward power reception, the reflectivity of transmitting and receiving signals in all planes, ease of installation, resistance to adverse weather conditions, and reduced multipath losses, CP antennas outperform LP antennas (Shin, Y. S., S. O. Park, and M. Lee,2005). Monopole antennas have become increasingly popular in recent years due to their low profile, low cost, wide bandwidths, and simple structure. The main disadvantage of CP antennas is their narrow bandwidth and large size. To compensate for these drawbacks, researchers must develop a small-scale, broadband CP antenna with a wide axial ratio bandwidth (Foudazi, A., H. R. Hassani, and S. M. A. Nezhad, 2012). Because of its ease of setup, integration, and multiband operation capabilities, planar geometry monopole antennas have received a lot of attention in recent years.
Various planar broadband antennas have been presented in (Midya, M., S. Bhattacharjee, and M. Mitra, 2019 to Donelli, M., T. Moriyama, and M. Manekiya, 2018) to improve AR bandwidth for various applications such as GSM and WLAN while keeping the size as small as possible. A triple-band G-shaped fed antenna has an ARBW of 53.92% and an impedance BW of 62.94% (Midya, M., S. Bhattacharjee, and M. Mitra, 2019). However, the axial ratio of this antenna is lower than its bandwidth. For wireless standards, (Wang, C.-J., M.-H. Shih, and L.-T. Chen, 2015), provide a bent-shaped feed with three slots, one T-shaped and two inverted-L slots etched in the ground plane, but with a lower BW. The antenna in (Ellis, M. S., 2016) is composed of a rectangular slot and a microstrip feed line. This antenna has an IBW of 90.2% and a 40% axial ratio of 3 dB.
For CP operation, (Li, Q, 2017) proposes an inverted-L strip and a modified ground plane. The Wi-Fi, Bluetooth, and WLAN bands, as well as a portion of the WLAN spectrum, are covered by the 10 dB reflection coefficient bandwidths. An L-shaped radiator with two opposing strips at ground plane corners covers 44% (2.35–3.66 GHz) and 70% (4.55–9.55 GHz) IBW with AR of 35.9% (2.40–3.45 GHz), 44.0% (4.65– 7.27 GHz), and 6.3% (8.13–8.66 GHz) in (Xu, R, 2017). (Gyasi, K. O, 2018) demonstrates a planar antenna with an IBW of 9.7% in the lower band, 11.3% in the middle band, and 60.2% in the upper band. The axial ratio bandwidths in the lower band are 4.9% and 58.6% in the upper band, respectively.