Ultra Compact Flexible Monopole Antennas for Tri-band Applications

Abstract

Two novel ultra-compact flexible tri-band antennas with coplanar waveguide (CPW) feed and asymmetric coplanar strip (ACS) feed arrangements are presented in this paper.These antennas are fabricated on an extremely thin substrate with dielectric constant (ε r ) 3.5 and loss tangent (tan δ) 0.027.The folded geometry of the antennas contributes to the size reduction.While the CPW-fed tri-band antenna (19 mm × 19 mm) exhibits bandwidth of 130 MHz, 600 MHz, and 1550 MHz in the lower, middle, and upper frequency bands, the ACS-fed tri-band antenna (19.5 mm × 15 mm) exhibits 80 MHz, 600 MHz, and 2220 MHz bandwidth, respectively.Design equations are developed, and an appropriate circuit model is recommended.The performance of the antenna is investigated for various bending conditions.Simple geometry, compactness, flexibility, and stability under bending conditions over multiband make these incredibly thin antennas quite appealing for ISM 2.4/5.2GHz, Wi-Fi 2.4/5 GHz, WLAN 2.4/5.2/5.8GHz and WiMAX 3.5/5.5GHz applications.