Microwave and Optical Technology Letters最新文献

Phase-based light detection and ranging (LiDAR) technology is emerging in the fields of industrial mapping, autonomous driving, and robotics, but the traditional phase-based ranging technology generally suffers from the problem that the ranging accuracy is inversely proportional to the measurement range under a single measurement frequency, the system structure is complicated, and the performance is unstable, and so forth. In this article, a new type of LiDAR system design based on phase ranging is proposed. The system adopts a 100 + 1 MHz double measuring ruler modulation light source, uses the laser to control the phase difference detection method of the same frequency reference, optimizes the structure of the transceiver optical system, and the design of AD8302 high-resolution signal phase discriminator circuit, builds a high-precision laser ranging system, and carries out the experiments on the measurement accuracy of the LiDAR ranging system. The experimental results show that the measurement accuracy of the system is millimeter level, which is simple, practical, and can meet the needs of a wide range of practical applications. This study provides a feasible and innovative solution for LiDAR technology in high-precision distance measurement.

Wide-band low-loss passive beam steering array presents to be essential part of the RF front-ends for high-speed detection during deep space exploration missions. In this letter, the copper-based additive manufacturing technology is proposed for the implementation of low-profile (~0.1λ) antenna design. Adopting the micro-coaxial line as the basic design unit enables wide bandwidth design. In addition, the broadband designs of Butler matrix, planar antenna element, and transmission transitions are proposed, respectively. The miniaturization of the metallic patch antenna is realized using a double slotted design, ensuring an array space of ~0.5λ, which beneficial for the low-lobe beam steering. Experimental results show that the antenna array with an overall size of 39 × 29 × 0.5 mm presents four beams located at ±14° and ±43°, respectively. The bandwidth of return loss better than −10 dB ranges from 65 to 71 GHz. The measured result matches well with the simulated ones, which makes its potential operation for satellite applications.

This letter presents a 0.01–50-GHz resistive matching power detector implemented in a commercial 0.15-$��\mathrm{\mu m}�$ GaAs pseudomorphic high electron mobility transistor technology. An analytical expression is derived for the voltage responsivity of the detector as a function of temperature. To compensate for the temperature dependence of the detector, bias diode topology and mesa resistor load are employed. For an input power of −20 dBm at 1 GHz, the maximum variation of the detector output voltage is less than 0.5 dB over the temperature from $��-�55�°�$C to $��85�°�$C. The detector's S11 is less than −8 dB, the dynamic range (DR) is 55 dB, and the maximum voltage responsivity is 700 V/W. An on-chip wideband capacitor with a bent-strip shape is designed for direct current blocking. The detector can be used for wideband power monitoring and power amplifier control loop for its high DR and temperature stability.

We report the design and theoretical study of a Ga-Sb-S chalcogenide glass-based photonic crystal fiber (PCF) structure for mid-infrared supercontinuum generation. The proposed design is engineered by adjusting the diameter of air holes in the cladding region and pitch, giving us control over the dispersion characteristics of the fiber. The optimized structure design offers the Zero Dispersion Wavelength of 5.2 μm. When pumped with 50 fs secant hyperbolic pulses of peak power 4.9 kW, for a fiber of length 8 mm at pump wavelength of 5 μm, the proposed structure design produces an ultra-broadband supercontinuum spectrum spanning 1.5–14 μm. Proposed PCF design should be helpful in, biomedical imaging, supercontinuum sources, biosesning, and optical coherence tomography.

Ultrawideband (UWB) time-reversal techniques are widely used in microwave imaging systems to detect and localize breast tumors. Measuring the scattering electromagnetic fields from a breast phantom can be time-reversed and back-propagated to refocus on a tumor. In this study, a Debye model was applied to the breast phantom. Using the decomposition of the time-reversal operator (TR-DORT), images were obtained in the UWB frequency range of 3.1–10.6 GHz. The conventional TR imaging method employs the free-space Green's function to refocus on the tumor, which degrades refocusing in a lossy and dispersive breast phantom. We propose the use of the cylindrical dyadic Green's function in a three-layer medium for TR imaging. The excitation system consists of a circular array of spiral antennas. The imaging results of the proposed Green's function in TR-DORT were subsequently calculated, indicating successful tumor detection in different application scenarios of the lossy and dispersive breast phantom.

The incredible growth of wireless technologies has led to an increase in demand of spectral resources for various communication systems. The allocated spectrum for GSM is insufficient to support applications that operate at high data rates (e.g., multimedia applications or 5G mobile communications). Orthogonal frequency division multiplexing (OFDM) and generalized frequency division multiplexing (GFDM) are the recent technologies with high data rates for multimedia applications and mobile communications. These are the perfect candidates for wireless applications and 5G technologies. In this paper, an in-depth study was presented where the multicarrier models of orthogonal frequency-division multiplexing (OFDM) and GFDM are integrated with a sub-Nyquist sampling architecture. The primary focus is to evaluate and compare their spectrum sensing performance. Also analyzed the performance of both OFDM and GFDM under sub-Nyquist sampling framework and measured the bit error rate (BER) as a function of the received signal-to-noise ratio (SNR).

Aiming for long-distance, high-resolution, passive imaging, we use fiber coupling to replace the spatial coupling of the segmented planar imaging detector for electro-optical reconnaissance imaging system and propose a novel incoherent interference imaging method, which avoids the problem that the resolution of the imaging system is limited by the size of the silicon wafer. The method uses a phase retrieval algorithm and does not need to measure the phase in the system, effectively avoiding the intrinsic jitter problem of fiber optics. The feasibility of the method in achieving target image reconstruction was verified through simulation; furthermore, an indoor two-dimensional discrete sampling imaging experiment for a simple four-rod target was conducted, and an outdoor one-dimensional feature identification experiment for a two-rod target was also performed. The results showed that the resolution exceeds the diffraction limit and the reconstruction error of target size is less than 3.5%.

This study proposes an ultra-wideband multilayer absorber by combining frequency selective surface (FSS) and absorbing material. The structure is composed by three layers which are FSS loaded with resistors, absorbing material at the bottom and each layer is separated by air. The FSS in bottom has good absorption performance at high frequency while the upper layer is used to achieve low-band absorption. To extend the absorption band to the low frequency, it further add a layer of absorbing material at the bottom. Equivalent circuit is employed to analyze the principle of the designed absorber. The simulation results show that an ultra-wide absorption band from 0.61 to 12.33 GHz with a fractional bandwidth of 181% is realized for both TE and TM waves under the normal incidence. Furthermore, the thickness of the structure is only 0.07λ_L, where λ_L represents the wavelength of the minimum operating frequency. The designed absorber is fabricated and measured, and the measurement is in good agreement with the simulation.

This paper designs a bandpass filter for D-band and 0.18 μm complementary metal oxide semiconductor (CMOS) process. The bandpass filter is composed of an inverted L-shaped coupling microstrip line and a cross-coupled resonator, and is coupled to produce two controlled transmission zeros. A defected ground structure is used to make a good impedance match. The designed filter has a 3 dB impedance bandwidth of 52 GHz (149–201 GHz) with a center frequency of 175 GHz and an insertion loss of 3.23 dB. The design of this paper is a CMOS 0.18 μm process capable of applying the D-band bandpass filter with the advantages of lower insertion loss, broadband, and compact size.

In this study, a novel bandpass filter (BPF) characterized by low insertion loss (IL) and the presence of two transmission zeros (TZs) based on integrated passive device (IPD) technology is introduced. The design incorporates a low-pass filter and a high-pass filter which both exhibit strong out-of-band suppression performance. The control structure for TZs is constructed by cascading the inductance and capacitance components. The TZ controlling structure primarily generates TZs at high frequencies, resulting in a further bandwidth enhancement in the stopband. The lumped circuit of the proposed BPF is first constructed, and rigorous design formulas are provided to assist in constructing the proposed design. After schematic optimization, the second step involves layout optimization and simulation based on the specific IPD process. Experimental results mounted on a printed circuit board demonstrate that the bandwidth spans from 3.3 to 4.2 GHz with an IL of only 2.0 dB at the center frequency. Additionally, this BPF achieves impressive sideband suppression, exceeding 18 dB in the 0–1.7 GHz range and 30 dB in the 9–15 GHz range. Remarkably, the BPF is exceptionally compact with only 0.5 mm × 1.0 mm (0.006λ_c × 0.012λ_c). The proposed BPF exhibits outstanding performance with minimal IL and extensive sideband suppression at such a compact size based on the IPD technology.