A Multiband Robust Planar Antenna for Wireless Handheld Devices

In this paper, a novel design of compact multi-band planar antenna is presented. Quarter-wavelength resonating slots are introduced on the radiating patch of a microstrip line fed monopole antenna. This arrangement provides reduced ground current effect. Moreover, ambient conditions like presence of nearby metallic structures, dielectric overlay, plastic casing, transceiver chips etc. are shown to have no significant effect on the antenna performance. This makes it a suitable candidate for applications in hand held devices. The input impedance of the antenna can be controlled by the slot position. A prototype tri-band antenna is designed for the 2.4/5.2/5.8 GHz wireless LAN frequency bands on a 0.813-mm thick RO4003 substrate with a dielectric constant of 3.55. The measured 10 dB return loss bandwidths cover and exceed the bandwidth requirements. The radiating patch has a compact dimension of 30x10 mm(2).