Microwave photonic channelized receiver can break through the electronic bottleneck, improve the throughput of satellite payload, and is expected to be widely used in broadband satellite communications. To solve the self-interference problem in the full-duplex satellite relay system, a microwave photonic channelized receiver with a self-interference cancellation (SIC) function is proposed in this paper. The equal interval division of broadband radio frequency (RF) signals is realized through polarization multiplexing technology and optical frequency shifting technology. In addition, by constructing a reference interference signal and matching the delay and amplitude in the optical domain, the self-interference signal is eliminated to avoid the receiver blockage caused by interference leakage. Theoretical derivation and experiment research are carried out, and a wideband signal with 3-GHz bandwidth is down-converted to six sub-channels with a frequency range of 0.5 GHz–1 GHz. Under the single-tone test, the isolation between sub-channels exceeds 31 dB, and the SIC depth exceeds 40 dB. When the sub-channels carry the 16quadrature amplitude modulation (QAM) signals with the bandwidth of 50 MHz, the SIC depth over 26 dB is achieved, and the error vector magnitude (EVM) is 7.6%. Under the two-tone test, the SFDR of the sub-channel is 93.5 dB.Hz ^2/3 .

Image-reject radio frequency (RF) receiver is the backbone of modern RF systems, but often suffers from limited bandwidth, local oscillator (LO) leakage, even-order distortion and I/Q imbalance. A wideband photonic image-reject RF receiver based on two phase-modulators (PMs) in a Sagnac loop and an I/Q balanced detector is proposed. In the experiment, excellent I/Q amplitude balance (<0.8 dB) and phase balance (<0.7 degrees) over a wide operating frequency from 8 to 40 GHz are achieved. Due to balanced detection, the even-order distortion and dc-offset are significantly suppressed. Combined with an analog intermediate frequency (IF) quadrature coupler, the image-reject RF receiver is implemented with a spurious free dynamic range (SFDR) of 99.4 dBHz2/3 and an image rejection of 50.3 dB. An antenna remoting RF vector signal with image interference is down-converted to the IF domain. Benefiting from the significant image rejection and Sagnac loop architectonics, a good constellation diagram and a low error vector magnitude (EVM) of the desired signal are obtained.

Radar target simulator (RTS) is extensively used in the development, debugging, and operation of automotive millimeter-wave radar systems. However, the performance of the traditional RTS based on digital radio frequency memory (DRFM) is limited by the complexity and spurious of radio frequency (RF) front end, the sampling rate of the analog-to-digital converter (ADC), and inherent delays in digital signal processing, which is hard to meet the urgent needs of wide bandwidth, low spurious distortion, high precision, and low delay. To solve this problem, a simple, multiband universal, high precision, and low-spur photonic RTS photonic RTS based on all-optical IQ upconverter is proposed. The experiment shows that the moving direction can be switched by flexible control of up-and down-frequency shifts, and accurate simulation of the target with different speeds can be achieved by a large-range-tunable Doppler frequency shift. In addition, the distance of the target can be flexibly tuned by optical delay, and the radar scattering cross section (RCS) can be simulated by wide-range power attenuation. Due to all-optical operation, the simulator has the advantages of adjustable working frequency ( L – K band), large modulation bandwidth (dc to gigahertz level), and high spurious suppression ( $>$ 30 dB). Moreover, the amplitude and phase of the generated simulated signal can also be adjusted, which is of great value in electronic warfare jamming and forwarding systems.

Radio frequency (RF) repeaters are often used in satellite communication, wireless wideband communication and electronic warfare systems for signal receiving, forwarding and processing. Due to frequency-dependent microwave devices, conventional electrical RF repeaters have limited bandwidth and are susceptible to electromagnetic interference. In this paper, a dual-channel photonic RF repeater using polarization-division multiplexing dual-parallel Mach-Zehnder modulator is proposed. The RF repeater is built entirely using optical methods and does not require any frequency-dependent equipment, thus enabling high operating frequency and large operating bandwidth. The modulator is used to perform frequency conversion on the received uplink/downlink RF signals, and the followed polarization controller and the balanced photodetector realize switching of the uplink and downlink RF channels. In the experiment, wide operating bandwidth (1-20 GHz), low channel crosstalk (>33 dB) and a large spurious-free dynamic range ( ${\rm{106\ dB\cdot Hz^{2/3}}}$ ) for the RF repeater are obtained. In addition, the channel switching of 16 quadrature amplitude modulation (QAM) RF signals with 120 Mbps data rate is demonstrated, while the adjacent channel power ratio (ACPR), demodulated constellation diagrams and the error vector magnitude (EVM) are evaluated.

Combined in-band full duplex-multiple input multiple output (IBFD–MIMO) technology can significantly improve spectrum efficiency and data throughput, and has broad application prospects in communications, radar, the Internet of Things (IoT), and other fields. Targeting the self-interference (SI) issue in microwave photonic-based IBFD–MIMO communication systems, a microwave photonic self-interference cancellation (SIC) method applied to the narrowband 2 × 2 IBFD–MIMO communication system was proposed, simulated, and analyzed. An interleaver was used to construct a polarization multiplexing dual optical frequency comb with a frequency shifting effect, generating a dual-channel reference interference signal. The programmable spectrum processor was employed for filtering, attenuation, and phase-shifting operations, ensuring amplitude and phase matching to eliminate the two self-interference (SI) signals. The simulation results show that the single-frequency SIC depth exceeds 45.8 dB, and the narrowband SIC depth under 30 MHz bandwidth exceeds 32.7 dB. After SIC, the desired signal, employing a 4QAM modulation format, can be demodulated with an error vector magnitude (EVM) as low as 4.7%. Additionally, further channel expansion and system performance optimization are prospected.