This numerical study proposes an enhancement technique of nonreciprocal phase shift in curved composite right/left-handed metamaterial lines loaded with corrugation structures at the microstrip edges. The numerical simulation results show that the appropriately designed corrugation structures enhance the nonreciprocity.
This paper proposes a dual-polarized filtering antenna with extracted-pole unit (EPU) using LTCC substrate. The EPU realizes the high skirt characteristic of the bandpass filter with transmission zeros (TZs) located near the passband without cross coupling. The filtering antenna with EPU is designed and fabricated in 28 GHz band for 5G Band-n257 (26.5-29.5 GHz). The measured $S$11 is less than −10.6 dB in Band-n257, and the isolation between two ports for dual polarization is greater than 20.0 dB. The measured peak antenna gain is 4.0 dBi at 28.8 GHz and the gain is larger than 2.5 dBi in Band-n257. The frequency characteristics of the measured antenna gain shows the high skirt characteristic out of band, which is in good agreement with electromagnetic (EM)-simulated results.
An electromagnetic coupled type microwave heating applicator using a zeroth-order resonator (ZOR) is proposed. The guide wavelength in ZOR can be infinite regardless of the physical length, which enables uniform heating in a wide area. The characteristics of a single ZOR whose zeroth-order resonant frequency is 2.44 GHz were investigated by simulations and experiments. The heating simulation results of the thin film show the length within which the power loss density became more than 50% normalized by the maximum was 0.428λ0, where λ0 is wavelength in vacuum. This means the uniformly heatable length is successfully extended in the 1D direction.
The impedance expansion method (IEM) is a circuit modeling technique based on the method of moments. The IEM has been extended mainly for application to wireless power transfer systems. For example, the IEM has been extended to consider the presence of perfectly conducting and dielectric/magnetic scatterers. This paper introduces the basic concept, theoretical extension, and recent application of the IEM.
In this paper, new multiband Doherty power amplifier design for 5G NR Sub-6 GHz handset applications is proposed. The proposed Doherty power amplifier is demonstrated experimentally with GaAs-HBT. A PAE of 38.9% and a NR ACLR of -37.8 dBc at an average output power of 27.4 dBm are measured at 3.75 GHz under 5G NR 100 MHz, DFT-s-OFDM, QPSK operation. Moreover, the proposed Doherty power amplifier maintains more than 34.0% efficiency with a NR ACLR of below -35.6 dBc from 3.35 GHz to 5.15 GHz, corresponding to 5G NR Band n77 and Band n79.
Boron doped diamond particles (BDDP) have been investigated using dielectric spectroscopy from 100 Hz to 10 GHz using a combination of microwave cavity perturbation and the broadband coaxial probe method. Raman and x-ray photoelectron spectroscopy demonstrate that the BDDP consist of both diamond and a considerable concentration of non-diamond carbon. The electrical conductivity increases with the boron to carbon (B/C) ratio in the fabrication process. The microwave complex permittivity also increases with increasing B/C ratio from, with loss tangent increasing from 0.4 to as large as unity, demonstrating the potential for BDDP in tuneable microwave absorber additives.
This paper proposes a novel shape optimization suitable for microwave matching circuits by hybridizing parameter optimization (PO) and topology optimization (TO). TO helps obtain new and innovative solutions to electromagnetic design and optimization without depending on the designer's knowledge and experience. However, TO is one of the ill-posed problems and might be therefore unsuitable for electronic circuit layouts, which are often constrained by process design rules and electrical characteristics specifications. To solve this problem, we combined the TO using the NGnet on-off method, which can create a continuous shape, with the PO to ensure a connection between terminals, and optimized the matching circuit for the microwave amplifiers. As a result, this hybrid-optimized circuit achieved a 38 % reduction in circuit size while achieving the same performance as when PO was performed alone. It suggests that this hybrid optimization can lead to an innovative circuit layout that is not constrained by parameters set by the designer.
A method of an equivalent loop current modeling of printed circuit board traces and components on printed circuit boards was investigated. A microstrip line (MSL) and parallel lines are used as test benches. The loop current is one of common electromagnetic field source models, and is composed of a signal and a return current in this case. One-dimensional convolutional neural network (CNN) was used as a classifier to estimate the size parameters of the loop current model. The results show a feasibility and necessity for improvement of the equivalent loop current modeling by the machine learning of the near-field information.
This paper proposes an efficiency enhancement technique in a full-duplex electrical-balanced duplexer (EBD) front-end based on a quadrature balanced harvester (QBHV) connection at the isolation EBD port. A circuit prototype employing GaN PA devices around 400 MHz with 40% harvester efficiency measured 25% efficiency improvement (1 dB) with better than 25 dB TX-RX isolation and nonlinearity performance similar to a standalone power amplifier (PA).
In this paper, a compact rejection filter is proposed based on 2.5-D spoof surface plasmon polariton (SSPP) structure and folded spilt-ring resonators (SRRs). By embedding the folded SRRs into periodic grooves of the 2.5-D SSPP transmission line, a rejection band is created in the ultra-wide passband, resulting in pass-rejection-pass frequency characteristics. The rejection band and the cut-off frequency of the filter can be adjusted independently by changing the geometrical parameters of the 2.5-D SSPP rejection unit. Because of the compact folding structure, the lateral size is reduced by 54% compared with the conventional 2-D SSPP rejection filter.
In this paper, the new output waveform equations of Class EF power amplifier (Class EF PA) are obtained by combining the switching operation mode and harmonic tuning through mathematical derivation. The waveform theory simplifies the design process of Class EF PA, improves the efficiency of Class EF PA. In order to simplify the matching process for Class EF PA, the third harmonic impedance in the form of pure reactance is proposed. A fabricated PA using CGH40010F gives that the output power is 40.4 dBm, the gain is 10.4 dB and the drain efficiency is 75.9 % at 3 GHz.
A low mutually coupled multiple-input multiple-output (MIMO) antenna is designed for on-chip millimetre-wave (mm-Wave) application. Two circularly polarized (CP) cylindrical dielectric resonator antennas (CDRA) with polarization diversity are placed over a double substrate silicon layer. Herein, a simple decoupling approach is applied to inhibit mutual coupling by introducing a metal plate in the substrate between the two DRAs. According to the simulation results, the inserted metallic plate improved isolation by 4-5 dB in the desired CP bandwidth. This is achieved while maintaining excellent radiation efficiency and gain, making the suggested antenna appropriate for mm-wave on-chip MIMO applications. (This paper has been submitted to Asia-Pacific Microwave Conference 2022 (APMC 2022) )
Recently, "Both-Side Retrodirective System" was proposed, as a beam convergence technique, for high power microwave transmission. To demonstrate the effectiveness of the both-side retrodirective system by experiment, the authors propose a 2-dimensional measurement equipment. Propagation in the parallel plate waveguide was analogized based on free-space propagation, and the theory and characteristics were clarified by simulation. The electric field distribution in the waveguide is measured by electric probe. As a result, it was confirmed that the beam formed in the waveguide was successfully measured. Thus, the effectiveness of 2-dimensional experiment system for both-side retrodirective system was shown.
A low-power, low-noise fully-integrated LNA has been studied operating the MOSFET in the moderated-inversion region. The most influential device for NF of the fully-integrated LNA is the parasitic resistance of the gate inductor, so the inductance of the gate inductor should be low, however, it exhibits a lower gain, therefore, gate size optimization is needed. In this work, 920 MHz cascode amplifiers with W of 0.5, 1.0, and 1.5 mm were studied. As result, 1.0 mm gate width exhibits optimum, s21 and NF showed 16.9 dB and 2.30 dB with 1.28 mW power consumption. TSMC 180-nm CMOS process was used.
To realize the combinations of wide field-of-view (FoV) and multi-beamforming capability with an affordable implementation as required by SKA mid-frequency dense array, this paper presents a broadband wide field-of-view true time-delay based multi-beamforming architecture guided by the concept of allocating beams over the full FoV.The system is designed as a two-dimensional silicon-based beamformer combined with a chessboard beam-selector and is able to produce 16 independent beams covering $\pm 45$ °scanning angle while maintaining a flexible digital multi-beamforming capability within the full optical FoV.Thus the design provides a feasible solution that fulfills the wide FoV,flexible multi-beamforming and cost-effective system design requirements for large-scale dense array.
Beamforming technique has been the major trend for the next-generation wireless communication system to overcome the high propagation loss transmitting through the air. This paper presents a highly integrated planar switched beam antenna module for 5G new-radio (NR) application. The module consisted of 1×4 array with a Butler matrix and a single-pole-quadruple-throw (SP4T) switch. Implemented with Rogers RO3010 as the substrate, the antenna module has shown the four beam steering directions of 14°, -40°, 49°, and -16° with a 10-dB impedance bandwidth from 35 to 41 GHz. The experimental results demonstrate a great potential for the 5G NR wireless applications.
In this paper, we propose extraction of thermal circuit based on experimentally obtained transient temperature of GaN HEMT. Also, we evaluated the thermal circuit using randomly changed power, which simulated a modulated signal such as TDD-LTE. A thermal circuit was extracted using a simple pulse-shape dissipation power. The temperature was confirmed to begin to rise at 10–4 sec, showed a trend of saturation at around 10 –2 sec, then began to rise again around 10 –1 sec. For formulation of this temperature rise, we used a 5-stage thermal resistance and capacitance circuit. We have evaluated the extracted circuit model using randomly changed power with a frequency of 1 kHz. Both measured and simulated temperature are agreement with tracking the power change. Therefore, we can conclude our methodology may play an import role in RF operation under dynamically changing power conditions such as TDD-LTE.
This paper investigates a concept for a 79 GHz millimeter-wave receiver (Rx) frontend optimized for highly linear frequency-modulated continuous-wave civil-automotive radars. It consists of a double-balanced passive ring mixer for the frequency down-conversion, and two highly-linear differential amplifiers as low-noise amplifier and driver for the local-oscillator (LO) signal. To prove the concept, the circuit is implemented in a 22nm FDSOI CMOS technology. It is also studied how the control of the threshold voltage by the back-gate (BG) biasing can increase the circuit performance. Leveraging this feature, no dc biasing is required for the passive mixer and the trade-off between gain and linearity of the amplifiers can be easily tuned with the BG voltage. To characterize the Rx, the chip is mounted on a print circuit board with external resistive loads. Measurements of the fabricated chip show a maximum differential voltage conversion gain (CG) of 10.8 dB at a $1 \mathrm{k}\Omega$ load and the minimum double side-band NF $\boldsymbol{(\text{NF}_{\text{dsb},\min})}$ of 9.7 dB with a 50Ω-load. The simulation shows that the $\boldsymbol{\text{NF}_{\text{dsb},\min}}$ can be further improved, while the Rx drives a higher resistive load. With a 1 kΩ load, the simulated NF dsb,min is 7.5 dB. In the measured RF signal range from -30 dBm to -5 dBm, the CG is nearly linear, and the simulated input-referred 1dB-compression-point is between -4 dBm to -2 dBm depending on the LO frequency. To the best knowledge of the authors, this is the highest reported.
Mm-wave communication using massive Multiple-Input Multiple Output (MIMO) is highly directional in nature, hence making beam scanning and alignment a crucial aspect. In high mobility scenarios, frequent beam scanning may incur a performance degradation due to high control overhead. In this paper, we have adopted a supervised learning approach to determine the precoders and combiners for a hybrid beamforming architecture. To avoid frequent beam scanning and switching, we propose an overhead-aware strategy that addresses a trade-off between the spectral efficiency (SE) and the overhead signalling. Simulations are performed using channel data generated using the open source channel simulator NYUSIM.
In this paper, a novel way for dual-band power amplifiers (PA) linearization is proposed based on spiking neuron networks (SNN). A dual-input dual-output SNN is interacted with classical memory polynomial model, which can largely reduce the computational complexity. The experimental results on a real PA show that the proposed method can reach similar linearization performance compared with traditional methods but with low energy consumption. This is the first time that the SNN is deployed for multi-band PA linearization. Future work is to develop a trainable SNN model for real-time PA linearization.
