Analysis, Design, and Fabrication of a High-Gain Low-Profile Metasurface Antenna Using Direct Feeding of Sievenpiper s HIS

Abstract

HISs have recently shown the ability to support leaky waves, and to excite plasmonic and HIS resonance frequency modes for use as an antenna. In this paper, we analyzed, designed, and fabricated a TMA by directly feeding edge-located HIS cells through a microstrip feeding network. In contrast to other metasurface antennas that necessitate an external antenna to excite metasurfaces, our approach is inspired by the TMA design methodology that directly feeds the HIS cells rather than using it as a reflector. We developed a circuit model for the proposed structure and compared the results with those obtained from full-wave simulations. In addition, our further objective was to simplify the structure based on the working principle of the proposed antenna. This objective was achieved by converting square patches into parallel strip lines, leading to an aperture efficiency of 0.77. This simplification also creates additional space to explore various resonant patterns on the top surface and the feeding network on the bottom surface of the TMA. Full-wave simulation results indicate that, despite the compact dimensions of the proposed array with 64 electrically small patch resonators (1.84λ*1.84λ*0.032λ, whereλis the free space wavelength at 6.0 GHz), it achieves a realized gain, HPBW of about 15.1 dBi and 28° respectively at 6 GHz. Finally, we constructed a prototype and conducted measurements to validate the design. Measured results demonstrate good agreement with simulation ones with a gain of about 13.5 (+-0.5) dBi and a HPBW of 27° at 6 GHz. The proposed TMA is scaled to fit within the required dimensions for smart handheld devices at higher frequencies, while maintaining high gain capability. The design s scalability, single-feed, and compact footprint make it optimal for diverse wireless communication systems, such as car to car communications.

Figures (14)

• Figure 1: (a) Front, (b) back, and (c) side views of the radiating cell, (d) an equivalent circuit model of the patch unit-cell, and (e) the simulation results of unit-cell using CST and its equivalent circuit model using ADS. [Noted that the schematic views of cells in (a)-(c) are in a different scale for a better illustration. Port 1, with an impedance of $\mathit{Z}_L$ = 70 $\Omega$, represents the load of the unit-cell, while port 2, with an impedance of $\mathit{Z}_0$ = 377 $\Omega$, represents the free-space wave impedance.]
• Figure 2: A schematic view of the TMA cell with dimensions of L = 11.28 mm, s = 0.125 mm, N = 4.45 mm, A = 2 mm, P = 2d = 11.53 mm, t = 0.813 mm, r = 0.6 mm (a) top, (b) bottom, and (c) perspective view. [Noted that the thickness of the cell in (c) is in a different scale for a better illustration.]
• Figure 3: (a) Unit-cell radiation pattern, (b) scattering parameters from the lumped port 1 ($S_{11}$) located at the load of the cell and from the waveguide port 2 ($S_{22}$) located at the waveguide incident port for illuminating the top surface of the radiating cells with a TEM mode (377 $\Omega$), and (c) the dependency of $S_{11}$ (dB) on the distance of the via-location between the center of the cell ($N=0$ mm) and maximum available distance of the via location from the center ($N=4.45$ mm).
• Figure 4: The distributions of the (a) electric field strength, (b) surface current strength and (c) magnetic field strength on the periodic unit-cells excited by a normal incident plane wave for different relative phases at the resonance frequency of 6.0 GHz.
• Figure 5: (a) The front view of TMA with eight strip line array, and (b) the distribution of surface current on the parallel strip TMA array at 6.0 GHz. (Noted that the square patch array is reduced to a strip array with metalizing just vertical slots in the patch cell, as shown in Fig. 2.)