Ultra-Wideband Frequency Modulated Continuous Wave Photonic Radar System for Three-Dimensional Terahertz Synthetic Aperture Radar Imaging

Abstract

Three-dimensional (3D) imaging remains an expensive and challenging task in the THz band. In this study, a frequency-modulated continuous-wave photonic radar system was presented in the 300-GHz band, instead of using electronic-based devices. The proposed system can obtain a 6-dB bandwidth of 120 GHz to achieve a range resolution of ~1.1 mm. The frequency sweep linearity of a laser source was calibrated with respect to the imaging distance and range resolution, through which a maximum detectable distance of ~800 mm was achieved with the collimated beam. To obtain the desired 3D information, the synthetic aperture radar (SAR) technique was introduced to the proposed system to achieve 3D imaging, which was not bounded by the fixed focal distance of a focus lens. It can provide a spatial resolution of ~1.5 mm within a 3D imaging range up to ~300 mm. The potential and limitations of SAR imaging schemes are discussed based on the theoretical and experimental results.

A New Extended Target Detection Method Based on the Maximum Eigenvalue of the Hermitian Matrix

“…According to the previous analysis, the covariance matrix of the high-resolution range profile sample is constructed for Equation (11). The formula of the covariance matrix is as follows:…”

“…Step 4: Connect each selected sliding window matrix block to construct the column vector as shown in Formula (11), and construct the Hermitian covariance matrix corresponding to its column vector according to Formula (40);…”

“…Stepped-frequency synthetic wideband radar has attracted much attention due to its advantages of anti-clutter, small instantaneous bandwidth, low hardware requirements, and easy waveform design. Compared with traditional low-resolution radar and conventional wideband radar, stepped-frequency synthetic wideband radar is of great significance in the development of modern wideband radar signals and has become a hot research direction [11][12][13][14][15].…”

Ultra-Wideband Multi-Octave Planar Interconnect for Multi-Band THz Communications

“…Therefore, ultrawideband (UWB) communications and multi-band communications using frequency division multiplexing (FDM) schemes in the THz band are critical factors in achieving Tbps communication links [4]. Besides communications, the availability of the vast bandwidth plays a vital role in the development of high-resolution sensors for ranging [5], non-destructive imaging [6], 3D imaging [7], and THz spectroscopy for material identification from fingerprints [8][9][10]. Indium phosphide (InP)-based uni-traveling carrier photodiodes (UTC-PDs) have an enormous potential for such UWB applications owing to the multi-octave tunable THz signal generation enabled by the photomixing technique [11,12].…”

“…Recently, InP-based UTC-PDs have exhibited UWB operation beyond 4 THz [13] and promising levels of output power, reaching over +15 dBm at 77 GHz [14], +3.4 dBm at 150 GHz [15], and -0.6 dBm at 240 GHz [16]. However, the conventional packaging technology based on metallic rectangular waveguide (WR) interfaces or antennas limits the operational bandwidth of broadband THz-PDs [7,8,[14][15][16]. On the other hand, although the use of silicon (Si) lenses enables UWB operation for free-space optics [9,13], their large physical size prevents planar integration into compact THz integrated circuits [17][18][19].…”