Liu Jinxian

4GHz∼50GHz wide bandwidth high linearity and low hysteresis magnetic circuit for magnetically tuned filter

This paper describes a design method of wide bandwidth, high linearity, low hysteresis magnetic circuit for magnetically tuned filter, and analyzes the key technology .Through the analysis of magnetic field, design a new type magnetic circuit, and improve the performance of the magnetic circuit. In the frequency band of 4GHz~50GHz, the hysteresis is less than 60MHz and the linearity deviation is less than 160MHz, meets the needs of wideband millimeter-wave test equipment. And put forward a transformation method of hysteresis loop, in this way, we can visually see the hysteresis and linearity, in wide frequency band.

Design of a Ka -band double balance mixer based on the marchand balun

A Ka-band double balance mxer based on the marchand balun is proposed in this paper. The new design is simulated and validated by the measurement. Measured results show that about 10dB typical conversion loss, high gain compression and about 10dB return loss are achieved across the bandwidth from 27GHz to 44GHz, and LO-to-RF isolations are higher than 20dB.The results of conversion loss and isolation characteristic are the best among the same type mixer operating in ultra wideband millimeter wave frequency band in the reported paper.

A novel physical parameters measuring method using wireless passive sensor in harsh environment

This paper presents a novel physical parameters measuring method using wireless passive microwave resonator for harsh environment. Even if ordinarily physical parameters sensors are very attractive for a lot of applications, they suffer from weak energy autonomy and they are not compatible with harsh environment. The sensors must work reliably in the high temperature or high pressure environment, and we can monitor the physical parameters without connecting the sensors directly. In order to overcome these problems, we have developed a new kind of wireless parameters sensor system using resonator. The wireless passive physical parameters sensor works in harsh environment. The receiving unit in the general environment can receive and process the reflect signal of the resonant frequency. When the physical parameters of monitoring are changed, the resonant frequency will be different. Accurate online monitoring of physical parameters is highly desirable inside various harsh environments. This method avoids the constraints of the harsh environments, reduces the cost and difficulty of the parameters sensor system. At the same time, this method in this paper can survive these harsh environments and provide continuous monitoring. In addition, this paper presents a way to suppress the background clutter effectively. The method not only can improve the receiving efficiency, but also can reduce the effect of background clutter on the physical parameters extraction in the harsh environments.

Design of a new power equalizer

In this paper, a new microstrip power equalizer based on branch resonator loaded resistor is presented. Fourth-order resonance structure is employed to synthesize the frequency response. The equilibrium depth is 12.4dB. For 7.5GHz–18GHz application, the input and output return loss of the power equalizer is greater than 10dB. By changing the characteristic impedance of the main transmission line, which is connected by the resonance branches, we obtain good standing wave ratio. Because no additional matching transformer is needed, the power equalizer is small and easy to be produced. The power equalizer has been widely used in traveling-wave tube amplifiers.

A new ultra-wideband multi-way coaxial power combiner

A novel ultra-wideband multi-way coaxial power combiner is presented in this paper. In the new structure, there is an extended coaxial waveguide cavity, where the microwave signal can be transmitted smoothly with little reflection, and 24 ultra-wideband coupling probe of great efficiency. The transmission waveguide type is changed from coaxial waveguide to parallel boards at the edge of the extended coaxial waveguide cavity. For 6GHz-18GHz ultra-wideband application, the output port of the coupling probe is technically designed with the λ/4 impedance matching. Simulation and measured results well agree with each other, showing that the insertion loss SR21 is around -2dB and the return loss SR11 is below -10dB, which is practically feasible for ultra-wideband power combining.

A novel highpass filter based on complementary split ring resonators

A novel highpass filter based on complementary split ring resonator (CSRR) is presented, the HPF has two-staged resonators, each resonator is obtained by improving traditional CSRR into rectangle-shaped CSRR. Equivalent circuit of CSRR will be studied in the paper and the HPF will be simulated in HFSS and measured. The HPF has a compact size of 7mm*10mm, its passband covers from 7GHz to 22GHz with an insert loss less than 2dB, the rejection below 6GHz is more than 30dB, which means this HPF has a sharp edge. Simulation results in HFSS and measurement results are greatly matched.

Design of a 100kHz∼20GHz microwave receiver front end module

A 100kHz~20GHz front end module has been proposed for the high performance hand-held spectrum analyzer. The proposed front end module is the key part of the microwave receiver. It takes use of modern microwave hybrid integrated technique and combines switch duplexer, types of filters, local oscillator frequency multiplexer, types of mixers and intermediate frequency amplifier filter together. It has advantages of volume reduction and performance increasement. The frequency-changing principle of the module is described, and then the switch duplexer and types of filters are simulated and analyzed. The module is fabricated and the measurement results is given. The module adopts fundamental mixing method. The noise figure of the front end module is less than 28dB, the input P-1dB compression point is higher than 6dBm, and the image frequency rejection is higher than 65dB. The total size of the module is 238.7mm×107mm×17.3mm. The number of the front end module produced is more than 200. Its fabrication and consistence are well. The average noise level of the hand-held spectrum analyzer with the proposed front end module is better than -140dBm in the whole band.