Improvement of System Compatibility through Coupling Reduction

This paper deals with various techniques in the form of modifications or additions which were developed to produce additional coupling reduction in existing systems. Although this has been the prime purpose, due consideration has been given to the effects of the different methods on the original objectives of the systems. Some of the techniques alter the radiation patterns and gains of the antennas involved. Consideration has been given to developing techniques which are operable over a broad band of frequencies in order not to restrict the operational requirements of the systems involved. Both analytical and experimental results are presented. Experiments were performed in convenient microwave frequency bands. However, by proper scaling with respect to frequency, it is possible to use the results given in this paper at other frequencies. One of the methods of coupling reduction described here is the compensating bridge. This bridge is formed with the addition of a cancellation link between two interfering systems. The bridge is balanced by adjusting the amplitude and phase of the power transmitted through the link to obtain high isolation. The distinct achievement here is the reduction of interference between two systems over a broad range of frequencies. This method is one of the most versatile since it can be readily extended to almost any frequency band. The use of corrugations in the form of circumferential trenches around the aperture of an antenna was found to offer a substantial reduction in coupling.