High Impedance Surface Reflector Research Articles

Backfire suppressed low profile aperture coupled stacked patch antenna backed by a high impedance surface (HIS) reflector for UHF RFID reader applications

In this paper, a backfire suppressed aperture coupled circularly polarized (CP) stacked patch antenna for universal ultra-high frequency (UHF) radio frequency identification applications is presented. Cross-polarized backfire radiation patterns were successfully suppressed by a planar high impedance surface (HIS) reflector. The size of the fabricated antenna is 250 × 250 × 26.9 mm3 (0.71λ0 × 0.71λ0 × 0.076λ0) and its peak gain value of 7.1 dBi is measured. The distance between the antenna and the HIS reflector is only 4.8 mm (0.014 λ0). The HIS reflector suppressed cross-pol backfire radiations by about 10 dB. Detailed antenna and HIS reflector design are discussed thoroughly in this paper. The presented backfire suppression technique using the HIS reflector is scalable to other applications and frequency bands. This paper demonstrates the feasibility of the HIS structure at UHF band.

Light‐weight wideband spiral antenna with a two‐layer circular HIS reflector: TL‐CirHISR spiral antenna

This study describes a light-weight wideband spiral antenna that radiates a unidirectional beam. To realise a light-weight antenna, a one-layer thick high-impedance surface reflector (HISR) for a reference spiral antenna is replaced by a two-layer circular HISR (TL-CirHISR). The TL-CirHISR is made of fan-shaped patches printed on a dielectric substrate. It is revealed that a voltage standing wave ratio (VSWR) of <2 and an axial ratio of <3 dB are obtained across a design frequency range of 3.2–10 GHz (a fractional bandwidth of ∼103%). A weight reduction of 50%, compared to the weight of the reference spiral antenna, is achieved. A prototype spiral antenna with the TL-CirHISR is fabricated and measured to confirm the analysed antenna characteristics, with good agreement between analysed and measured results obtained.

A Low-Profile Wideband Dual-Polarized Antenna Based on an Improved HIS and Its Broad-Angle Beam-Scanning Array

A low-profile wideband dual-polarized antenna with an improved high-impedance surface (HIS) reflector is proposed. Dual-polarized radiation is excited by feeding a set of crossed dipoles. Low profile is achieved by utilizing an improved HIS reflector. Good impedance characteristics are realized by inserting small square cells among the primary hexagonal cells of the HIS. Two shorting pins and four parasites are introduced to increase port-to-port isolation and improve impedance matching, respectively. A prototype with profile 7.5 mm (about 0.06$\lambda$ and $\lambda$ equals to the wavelength at center frequency) was fabricated and measured. The experiment results show that the antenna element achieves 43$\%$ bandwidth ($\vert { S_{11}}\vert$<; $$-$10 dB) from 2.0 to 3.1 GHz. The polarization isolation between those two ports is larger than 25 dB. The element was then extended to an eight-element phased array. The measured results demonstrate that the array can scan $\;\pm\text{50}^{\circ }$ for either polarization from 2.0 to 2.6 GHz.

Tri‐band HIS backed spiral antenna for wireless LAN applications

ABSTRACTThis study reports the performance of an Archimedean spiral antenna, which exhibits unidirectional circularly polarized radiation patterns with a peak gain &gt;8 dBic in the lower (2.4–2.485 GHz) and upper (5.15–5.35 and 5.725–5.875 GHz) Wireless local area network frequency bands. The required backlobe suppression and impedance match are obtained by placing a multiresonant high impedance surface (HIS) in close proximity to the radiating aperture. Simulated and measured radiation patterns are shown at the center frequency of all three channels and a comparison of the key performance metrics is made with free space and metal backed antenna arrangements to demonstrate the enhancements which are attributed to the HIS reflector. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1116–1121, 2015

Low-profile dual-polarized patch antenna with HIS reflector for base station application

A coax-feed low-profile dual-polarized patch antenna with high impedance surface (HIS) reflector is presented. The proposed antenna contains two pairs of narrow slots along the diagonals and two pairs of T-shaped slots along the centerlines, which keep the cross-polarization under −38 dB. By introducing two short pins, the isolation between the two ports remains more than 36 dB in the whole bandwidth. Low profile and high front–back ratio characteristics are achieved by using the HIS reflector, which is also applied to enhance the performance of two-element array. The height of the antenna is less than λ/8 and the front–back ratio is better than 35 dB. The mutual coupling lower than −31 dB is obtained for the array design with the patches placed 0.8λ apart. The proposed antenna which covers a −10-dB reflection coefficient bandwidth of 2.28–2.75 GHz can be used as the low-profile base station antenna for WiMAX and LTE applications.

A Reconfigurable Plate ZAGI Antenna Using HIS Reflector for Gain Increasing

A novel design of a Plate ZAGI Antenna with HIS reflector is proposed, analyzed, simulated and implemented in this paper. In this Antenna instead of normal reflectors we use a high impedance surface reflector. It is made of continu- ous metal that conducts dc current and eliminates ac current with a certain bandwidth. This new surface omits surface waves and so, image currents are not phase reversed. Simulation and experimental results show a very considerable gain increasing in proposed antenna against usual antenna.