Design of Miniaturized and Polarization-Insensitive Double-Layer Frequency Selective Surface Based on Meander Lines

The work presented in this paper concerns a method for the miniaturized frequency selective surface (FSS) based on the meander lines. A miniaturized dual-bandstop FSS structure based on meander lines with spiral-shape is proposed and simulated. The equivalent circuit and current distributions are introduced to explain the FSS performance. The size of the unit cell is 10 mm, which is about 0.037 wavelength at the first resonant frequency. Simulation results indicate that the proposed FSS has a frequency shift smaller than 1% for different polarizations with an oblique incident angle of 60°. A prototype of the FSS is fabricated and measured. The measurement results show that the FSS is polarization-insensitive and angle-insensitive.

A compact parallel coupled meander lines shaped composite right/left-handed transmission line (CRLH-TL) based symmetric quasi-0 dB coupler

In this paper, parallel coupled meander lines (PCML) composite right/left-handed transmission line (CRLH-TL) based symmetrical quasi-0 dB coupled-line coupler is presented. Proposed coupler shows measured backward wave coupling level of 0.81 dB at frequency of 6.17 GHz with 3 dB fractional bandwidth (FBW) of 12.64%. Throughout the 3 dB frequency range (5.78–6.56 GHz), isolation and insertion loss of the coupler is better than 24 dB. Overall size of the proposed coupler is 19.6 × 12.1 mm. An equivalent lumped LC circuit model of the coupler is demonstrated. Measured results of the coupler show good agreement with the electromagnetic (EM) simulated and lumped LC circuit model simulated results, which validates proposed coupler design and its performance.