An innovative and effective photonics-based radio frequency (RF) spectrum scanner is presented and demonstrated, enabling the detection in the 0.5–28.5 GHz range. The proposed receiver scans the whole frequency range at discrete steps, down-converting at baseband single portions of the detected spectrum, where they can be precisely acquired, without using RF bandpass filters nor optical filters. The wideband scansion is achieved by simply tuning an optical carrier only, avoiding the use of an RF synthesizer or of multiple parallel local oscillators. In more detail, the optical carrier is modulated by the detected RF signal through an electro-optical modulator, and photomixed with an optical local oscillator to down-convert the modulation sideband to baseband. The optical carrier also feeds an optical frequency comb generator—driven by a fixed RF oscillator at 1 GHz—whose output injects the local oscillator. This way, the optical carrier and oscillator are phase locked and can be tuned at steps of 1 GHz. The developed demonstrator achieves an input range up to 28.5 GHz, and a simulative analysis suggests the capability of exceeding the 0.5–40 GHz range employing commercially available devices. Moreover, it shows a linear dynamic range of 160 dB/Hz and a spuriousfree dynamic range of 109 dB/Hz2/3, aligned with the state-of-the-art broadband RF receivers. The proposed solution appears to fulfill the performance requirements of the demanding electronic support measures applications, with the potentials for largely reducing the receiver size.
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