Zhenhai Shao

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.

W-band high bit passive phase shifter for automotive radar applications in BiCMOS

This paper presents a 65–85 GHz 5-bit passive phase shifter at the desired frequency of 77 GHz, using CMOS switches available in the 0.13 µm SiGe BiCMOS process. The phase shifter is based on a low-pass π-network and CMOS passive transistors. The RMS phase error, the insertion loss and the VSWR is less than 3.5°, −20 dB and 2 at 77 GHz respectively, so it is possible to precede this design with a high gain LNA without loss of system linearity or input power handling and it is convenient for afterwards signal processing.

Database design of GPRS-oriented remote meter reading system

First, the advantage of GPRS-oriented remote reading system is displayed. According to the hardware data collecting system for meter reading which is illustrated bellow, a software design model for sending and collecting a variety of meter data is given. At last, theform of these data stored in the database is presented by several data sheets, and the drawback of the database design is introduced.

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.

A power supply design based on LT3748

This paper describes in detail how to select components of the peripheral circuits of LT3748. In this paper, the LT3748 is introduced to produce an 8Vout at 3A from the nominal input voltage -48V with an operating input voltage range of -38.4V to -72V, where -48V is a common telecommunications equipment voltage. The test results show the output voltage and the current meet the demand of the project and the efficiency of the circuit is about 70%.

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.

Sparse Sampled MIMO radar for angle-range-doppler imaging

MIMO radar can provide higher resolution, improve sensitivity, and increase parameter identifiability without considering sparse sampled. Sparse signal recovery algorithms can offer improved estimation when the scene of interest contains a limited number of targets. In this paper, we present a modified approach to sparse signal recovery. The proposed approach follows an lq-norm constraint (for 0<;0<;1) and can provide increased sparsity via iterative minimization compared to existing approaches. Simulation results show the proposed approach provides superior performance for sparse MIMO radar imaging applications at a low computational cost.

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.