Real-Time Spectrum Sniffer for Cognitive Radio Based on Rotman Lens Spectrum Decomposer

We introduce the concept of an energy-detection Rotman-lens spectrum decomposer (RLSD) real-time spectrum-sniffer (RTSS) for cognitive radio. Compared to a previously existing RTSS, the RLSD-RTSS offers the advantages of being 1) Based an a simpler and lower-cost purely passive structure, 2) Easier to design and easily amenable to tunability, 3) Of much broader bandwidth, and 4) Of accommodating more channels. The electrical size of the device is electrically larger, but perfectly acceptable in the millimeter-wave frequency range. The proposed RLSD-RTSS is demonstrated theoretically and experimentally, and is shown to support tunability in terms of both bandwidth-resolution and operation band. Given its unique features, this device may find wide applications in 5G UHD and 3-D video systems.