Compact Metasurface-based Dual-band Antenna for OFF-Body Communications

This paper presents a metasurface-based monopole antenna (MSBMA) to cover 2.4 GHz ISM and 3.5 GHz WiMAX band for WBAN applications. The behavior is achieved by exciting the dual modes of the metasurface, which are TM
10
mode at 2.45 GHz and TM
20
mode at higher bands, using CPW fedmonopole radiators. The modes of operations are characterized by the dispersion curves of unit cells for 2×2 metasurface. The individual unit-cell (UC) is in the conventional rectangular shape, and that is designed using the theoretical transmission-line model. Then CST Microwave studio is used to design the MSBMA. The metasurface is used for dual-band generation as well as back-radiation reduction. The back-radiation reduction improves the overall performance in free space (FS) and on body (OB). On the body, the gain performance is increased to 6.90 dBi in the lowerfrequency-band (LFB) and 5.11 dBi in the higher-frequency-band (HFB). Both in FS and OB, the antenna provides an impedance bandwidth of 310 MHz in the LFB and 420 MHz in the HFB. For safety uses of the proposed antenna, the specific absorption rate (SAR) under the 10g standard is evaluated, which shows that the presence of the metasurface improves it by 99.68 % at 2.45 GHz and by 99.26% at 3.5 GHz.