By coupling a stub-loaded open-loop resonator onto the back of a CPW-fed mirrored-L monopole, a novel triple-band planar antenna has been achieved and is presented. The proposed antenna features a compact structure with reasonable gains. The measured bandwidths for the distinct triple-band are 2. GHz. Omnidirectional radiation patterns for the three bands are observed. Simulations are confirmed by the experimental results, which ensure that the proposed antenna is well suited for WiFi and WiMAX applications.Introduction: The Worldwide Interoperability for Microwave Access (WiMAX) has integrated with the wireless local area network (WLAN) or WiFi as a very promising technology in the broadband wireless access (BWA). In addition to those licence-free and ISM bands: 2.4 GHz (2.40 -2.48 GHz), 5.2 GHz (5.15 -5.35 GHz) and 5.8 GHz (5.725-5.850 GHz) used by WiFi, the WiMAX allocates the licensed spectrum of the 2.5 GHz band (2.50 -2.69 GHz) and the 3.5 GHz band (3.4 -3.69 GHz) for its delivery. Hence, these standards would have to be implemented simultaneously in future communications systems, which propels the demand for the compact antenna designs with multiband radiation characteristics. Several dual-band and tripleband planar monopole antennas have been reported [1][2][3][4][5]. However, most of them were addressed to the needs of WLAN/WiFi applications [1-3] and personal communication systems [4], very limited compact planar antenna designs have included the distinct licensed bands of 2.5 and 3.5 GHz for WiMAX application. Recently, a dual wideband printed monopole antenna for WLAN/WiMAX was proposed [5]. The antenna has a simple structure and a very wide frequency coverage in the lower-band, from 2 to 4.16 GHz. However, there are many other existing narrowband services such as C-band satellite communications that have occupied some licensed frequency bands. To avoid frequency collision and minimise interference, additional bandpass filters are required to be added into the system when a very wideband antenna is used. Alternatively, embedding an EM-wave filter structure onto a planar antenna is one of the cost-effective methods [6].In this Letter, a distinct triple-band resonator-loaded antenna employing a symmetrical CPW feed for WiFi and WiMAX applications is proposed. The antenna comprises a mirrored-L monopole that is driven by a 50 V CPW transmission line on one side. A stub-loaded open-loop resonator is electromagnetically coupled on the other side. The distinct frequency bands are able to be determined by controlling the parameters of the open-loop resonator, and the coupling between the monopole and the resonator. Details of the antenna design are presented and discussed.Simulations are compared to experimental results.
Abstract-This paper proposes a metamaterial reflective surface (MRS) as a superstrate for a single-feed circularly polarized microstrip patch antenna (SFCP-MPA). It illustrates a simultaneous enhancement on antenna gain, impedance bandwidth (ZBW) and axial-ratio bandwidth (ARBW) by adding the MRS atop the SFCP-MPA. The MRS can enhance the ZBW and ARBW by 3.5 and 9.9 times, respectively, compared to the circularly polarized patch source. Moreover, the gain of the CP-MPA with the MRS is 7 dB higher than that of the conventional CP-MPA. The small spacing between the MRS and patch source is another merit in the present design, which is as low as λ • /16, as it results in a low-profile antenna design that well suits modern wireless communications.
SUMMARYBandwidth and gain enhancement of microstrip patch antennas (MPAs) is proposed using reflective metasurface (RMS) as a superstrate. Two different types of the RMS, namely-the double split-ring resonator (DSR) and double closed-ring resonator (DCR) are separately investigated. The two antenna prototypes were manufactured, measured and compared. The experimental results confirm that the RMS loaded MPAs achieve high-gain as well as bandwidth improvement. The desinged antenna using the RMS as a superstrate has a high-gain of over 9.0 dBi and a wide impedance bandwidth of over 13%. The RMS is also utilized to achieve a thin antenna with a cavity height of 6 mm, which is equivalent to λ/21 at the center frequency of 2.45 GHz. At the same time, the cross polarization level and front-to-back ratio of these antennas are also examined.
This article presents a metasurfaced patch antenna in which the metasurface acts as a superstrate/cover placed atop a 2.45-GHz patch antenna, at a small distance. The metasurface is a Mu-nearzero (MNZ) type, which gives a near-zero index of refraction. The MNZ metasurface consists of 4  4 double-closed-loop resonators printed on a thin FR4 dielectric slab. The proposed antenna is low-cost and lowprofile, having overall dimensions of 0.86 k  0.86 k  0.07 k. The simulation and experimental results confirm that the metasurfaced antenna not only has simultaneous enhancements on broadside gain and bandwidth, but also improves antenna efficiency.
A cost-effective solution for the performance enhancement of circularly polarised array antennas by using a thin metasurface is proposed. The array is considered as reconfigurable, where an antenna engineer can arbitrarily add the metasurface onto the original array according to application requirements. Once added, the new array forms a subwavelength cavity having a compact form factor of 1.63λ o × 1.63λ o × 0.07λ o at 2.45 GHz. The array antenna is demonstrated to have remarkable enhancement on its performance metrics including boresight gain (12.8 dBic), axial-ratio bandwidth (46.5%) and 10 dBic gain bandwidth (24.4%). More interestingly, a sidelobe suppression level of 4.4 dB is achieved.
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