Low cost diversity antennas for low power wireless base stations

The paper presents two diversity antenna configurations, where the antenna elements are housed inside the base station chassis. The first is an indoor wireless PABX base station operating at 1900 MHz. The second is an outdoor wireless base station for serving microcells, where the range might be up to 200 m. This results in a design which is aesthetically pleasing, compact, and one where the antennas are protected from damage. The examples shown are for narrowband applications and this has enabled the use of low profile electrically small monopoles. However, the local environment inside the base station has to be included at the outset of the antenna design process, since this has a large influence on the antenna radiation pattern. For the cases shown, ground plane shaping and/or edge excitation has been used to increase radiation in the backward hemisphere. At the same time, the ground plane provides shielding for the antenna elements from objects (PCBs, walls, etc.) behind the ground plane, such that no detuning occurs