Radar Systems are among the most widely used communication systems. They are used in both military and civilian applications such as: Remote sensing, Microwave Sounder (MWR), Ship Navigation, and Air Traffic Control (ATC). Radar systems use high power electromagnetic signals to detect and locate faraway objects such as aircrafts or ships. The development of radar started in the 1930s, before and during the Second World War, however it is still an important area of research with its critical role in various applications.
Typically, radar systems require high-power to cover large areas. Such high power cannot be derived from one source. Therefore, multiple power sources are combined together to achieve such high power, where these sources must be synchronized and in-phase. In the normal operation of a traditional power combining network, the internal matching of the network is the most important design factor, so that the power sources will be combined without any significant losses. However, in case of failure of any source before the combining stage, the power of the working sources will be reflected and dissipated into a protection circuit causing huge losses and degradation in the overall system performance.
In theory, it is impossible for any three-port passive networks (such as power combiners) to satisfy three conditions: losslesssness, internal matching, and the reciprocity. The power combining is usually made out of conducting linear material to satisfy both the reciprocity and the losslessness conditions. Hence, the failure of one source at the combiner port leads to reflection as the network theoretically cannot be internally matched. To overcome this limitation, the power combining system must deploy active components to avoid the mismatch situations.
In this thesis, we propose a system which improves the performance of power combining networks by detecting the failure events of the malfunctioning source and directs the properly-functioning source to the output by the aid of electrically controlled switches. The proposed system uses directional couplers to extract a power sample from the signal passing through each branch. We build and test the controlling subsystem where all the required elements are integrated up to the proposed design. Moreover, we propose a novel Band-Pass Filter (BPF) structure using coupled structure resonators to reject the out band and reduce the noise power as a pre-filtering stage to the energy detection. Also, energy detection technique is used to identify which power source is still in operation. Finally, we provide closed-form mathematical expressions for the performance of the proposed energy detector in terms of the probability of false alarm and detection.