Increasing Isolation between Colocated Antennas Using a Spatial Notch

Abstract—This letter presents an antenna configuration to achieve a coupling reduction between colocated antennas. Ap-plication of an adaptive spatial notch enables this functionality. Analytical results are obtained, which show good resemblance to simulated and measured results, performed on a prototype manufactured to operate around 2.5 GHz. Coupling reduction of 50 dB has been measured. The antenna impedance is also influ-enced because of this configuration and shows an better than 15 dB at the frequency of interest. In addition, the radiation pattern of both antennas is influenced. This can be seen as an advantage or a disadvantage, depending on the application. Index Terms—Antenna isolation, antenna measurements, electromagnetic coupling, near field. I