Xueyong Zhu

Ka-band rectangular waveguide power dividers

Waveguide T-junction and directional couplers are widely used in microwave/millimeter wave systems, because its circuit is simply and easily to be designed and fabricated. In this paper, a ka-band E-plane rectangular waveguide power divider is proposed and optimized. The first level of the network is the T-junction, which can halve the power for the first time, and the second level are two 3dB directional couplers, which are designed accordingly to the couple of electromagnetic field between seven waveguide slots. It is developed with excellent isolation between output ports. The good transmission characteristic can be obtained at ka band.

High Performance Waveform Generator Design for Full-Coherent Millimeter-Wave Radar

Millimeter-wave radar has attracted much attention as a replacement of some infrared or laser systems currently in use. In this paper, an approach of developing high performance waveform for full-coherent millimeter-wave radar is proposed. With good frequency configuration and optimal utilization of DDS (direct digital synthesizer), PLL (phase locked loop) and FPGA (field programming gate array), the developed radar waveform generator implemented with low complexity has the good performance of both spectrum purity (phase noise and spur level) and switching speed. The measurement results show that, in S/C band, the local oscillators bandwidth is 480MHz and the minimum frequency step is 15MHz, the spur level is better than -65dBc, the phase noise level is better than -94dBc/Hz@1kHz, the maximum frequency switching time is less than 15mus.

The near‐field processing and narrowband imaging algorithm for MIMO array

Purpose – Imaging is a really difficult problem when systems are implemented in the near‐field region and real‐time needs. The purpose of this paper is to consider a novel system model and present a narrowband 2‐D imaging algorithm in the near‐field region and under the real time constraint.Design/methodology/approach – The first part of this paper proposes a novel approximation for the round‐trip distance of the near‐field echoed data based on a 2‐D synthetic aperture planar array. The second part of this work proposes a near‐field narrow imaging algorithm based on the above system model. Narrowband waveforms are employed in the array system, so that the range alignment and decoupling in range‐azimuth are not necessary.Findings – The errors of the proposed approximation are much smaller as compared with those of the Fresnel approximation. For example, the errors of the proposed approximation are negligible when the antenna is fixed at (0, 0). In other cases, the errors are decreased by almost 50 percent....

2.4GHz/5GHz wide-band receiver in a wireless communication system based on 4×4 MIMO technology

This paper presents a wide-band receiver at 2.4GHz and 5GHz for 4×4 MIMO wireless communication system. This design is proposed and realized using super heterodyne architecture solution. Dual conversion structure is used in this receiver system. The receiver benefits from RF part, control part and phase shifter part. The carrier of this transceiver is 1.82GHz and 4.42GHz, and the local oscillation providing carrier mainly consists of PLL and DDS. Both 70MHz and 580MHz are intermediate frequency of the receiver, which have 8MHz and 150MHz pass-band channel respectively. The developed receiver is used for field experiments in outdoor wireless communications. The measurement result shows that this receiver developed works well.

The research of homodyne LFMCW radar

Nowadays, the 24GHz band is allowed temporarily for car radars by European Telecommunication Standards Institute (ETSI) until 2013, when the hardware technology (MMICs, antennas, etc.) will be mature enough to enable the development and production of automotive radar modules at the 76-81 GHz band. In this paper, a common structure of homodyne LFMCW (Liner Frequency Modulated Continuous Wave) radar transmitted-received front end and the radar signal processing are discussed. Moreover, taking the 76GHz automatic cruise radar as an example, this paper will discuss the basic measurement principle of relative distance and velocity to target. In the end, some significant conclusions guiding on the project will be achieved.

Research on Cross-Polarization Interference Canceller with blind adaptive algorithm

Co-Channel Dual Polarization (CCDP) technology is an efficient way to double the link capacity in modern communication system. However, the consequent polarization interferences become an inevitable problem to fight. Therefore, a Cross-Polarization Interference Canceller (XPIC) is necessary against the cross-talks. This paper focuses on the baseband XPIC technology and builds a simulink model to show the XPIC performance in 256-quadrature amplitude modulation (QAM) system. Meanwhile, a two-stage blind adaptive algorithm joint constant modulus algorithm (CMA) and Decision-Directed LMS (DDLMS) is introduced to XPIC to enhance system performance. Simulation results show the feasibility and effectiveness.

Design of a novel broadband power divider based on oversized-coaxial and radial waveguide

This paper proposes an improved 1 to 4 power divider based on oversized-coaxial and radial waveguide. To widen the bandwidth of the divider/combiner, an axially symmetric oversized coaxial waveguide is used to transform input to the radial waveguide, and at the bottom of the radial waveguide, stepped-impedance technology is used to realize the impedance match. According to EM simulations, the simulated −20dB return loss bandwidth is approximately 44.25% (ranging from 22 to 34.5GHz), and good amplitude imbalance and phase imbalance are observed in the band. This structure has properties of not only a wide band, low insertion loss and high output power, but also a small size, a high power combining efficiency and efficient heat sinking, and has potential for broadband high power combination.

The near-field processing for a 2-D narrow imaging algorithm

This paper proposes a novel approximation for the round-trip distance of the near-field echoed data based on a planar 2-D synthetic aperture planar array. A near-field narrow imaging algorithm based on the novel approximation is proposed. Comparisons of the proposed approximation and the Fresnel approximation are also demonstrated. The errors of the proposed approximation are negligible when the antenna is fixed at (0, 0). In other cases, the errors decreased by almost 50 percent. Moreover, in our array system, narrow waveforms are employed, and thus, the range alignment and decoupling in range-azimuth are not necessary. The simulation results verify the validity of the algorithm.

CMOS and BiCMOS VCO — Status and trends

This paper gives a brief overview of voltage controlled oscillator(VCO) based on Si CMOS and SiGeBiCMOS process technologies. The status of designing techniques for high performance VCO is summarized because of its importance for high-speed communication systems and radar sensors. Then, the development tendency of VCO is introduced.

Design of Ka-band substrate integrated waveguide power dividers/combiners

In this paper, two classes of Ka-band Substrate Integrated Waveguide(SIW) power divider are presented and studied. The advantages of the SIW technique are its low profile, low-lost, mass-productive, ease of fabrication and fully integrated with planar circuits. All the modules are designed to be operated in a wide frequency range. The Y-junction shows a bandwidth of 29.4%.