Compact Dual-band ACS-fed Monopole Omnidirectional Antenna for 2.4/5.2/5.8 GHz WLAN Applications

A compact dual-band asymmetric coplanar strip (ACS) fed printed monopole omnidirectional antenna with three radiating structures for 2.4/5 GHz WLAN/Bluetooth applications is presented. The designed antenna comprises of a simple ACS-fed (Asymmetric Coplanar Strip) monopole and three different strip radiating elements. It occupies a very compact overall size of 15 x 24 mm(2) including the ground plane, which is only about 0.12 lambda x 0.20 lambda (lambda is the wavelength at the frequency of 2.45 GHz in free space). So, it has the characteristics of miniaturization. A resonant mode at 2.45 GHz is created by adding a inverted-L branch, and the resonant mode at 5.62 GHz is co-produced by the horizontal strip and vertical strip including an element which is like a Chinese Tai Chi fish. Dual desired resonant frequencies achieved, and each of them can be tuned independently. Both the simulated and measured results show reasonable agreement, and the measured dates show that the antenna has an impedance bandwidth of 90 MHz (2.4-2.49 GHz) and 810 MHz (5.07-5.88 GHz), and a reflection coefficient of less than -10 dB, it is suitable for WLAN 2.4/5.2/5.8 GHz applications and 2.4 GHz Bluetooth bands.