Electromagnetic field simulators are routinely used to design antenna structures and achieve the desired performance, including radiation pattern directivity and gain, polarization, standing wave ratio (SWR), and other pertinent parameters. However, there are many cases where the antenna is strongly affected by its surrounding environment and failure to take this into consideration can lead to poor installed performance. Nulls can be introduced in the radiation pattern leading to drops in communication range in certain directions. Reflections from nearby objects may couple back into the antenna increasing the SWR to intolerable levels. The antenna may also receive strong signals from neighboring transmitters causing interference and reducing operability. In severe cases, it may be necessary to silence one radio system to enable another to function correctly. This is clearly an undesirable situation.
This article is copyright of IEEE December 2008