A compact monopole antenna with a defected ground plane for multi-band applications

The primary interest of this work is to create a multi-band antenna that can be used for various wireless LAN standards (e.g. WiFi, WiMax), while occupying a small area. It will be shown that this can be achieved by etching an L-shaped slot in the ground plane of a UWB grounded monopole antenna. The resulting "defected ground plane" creates an additional two resonances in the input impedance of the antenna, whose locations can be adjusted according to the size and location of the slot. The design is completely uniplanar, it is very low profile, and it does not require the use of any vias or lumped-element components. It is therefore easy to fabricate using standard photolithographic procedures at a very reasonable cost, thus making it ideal for use in wireless LAN devices.