Fig. 2: Demonstration of the frequency-comb-steered linear quasi-TTD beamformer. | Nature Communications

Fig. 2: Demonstration of the frequency-comb-steered linear quasi-TTD beamformer.

From: Frequency-comb-steered ultrawideband quasi-true-time-delay beamformer for integrated sensing and communication

Fig. 2

a Experimental setup. Dual-frequency combs (i.e., signal comb and LO comb) are generated with cascaded modulators. The signal comb is modulated by an intermediate-frequency LFM signal, while the LO comb is frequency-shifted through carrier-suppressed single-sideband (CS-SSB) modulation. The dual combs are then amplified, demultiplexed, and heterodyned to generate microwave signals that feed a 16-element Vivaldi antenna array. The inset shows the antenna’s picture. EDFA erbium-doped fiber amplifier, WDM DEMUX wavelength division multiplexing demultiplexer, Opt Freq optical frequency, Tx transmitter. b Spectrum of the dual combs. The highlighted 16 channels are used for beamforming. c, d Frequency and phase offset of the transmitted LFM signals in each channel, compared to the 9th channel. Freq., frequency. e Radiation patterns at the instantaneous frequency of 15 GHz when the beam direction is −30°, −15°, 0°, +15°, and +30°, respectively. The main lobes are highlighted. Angles from –30° to +30° are indicated by both color and marker shape. Exp., experiment.

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