170 GHz gyrotron utilized to heat the plasma in the thermonuclear fusion is a power source device and the most important component of the electron cyclotron resonance system. The problem of the overlarge power density in the collector will restrict the increase of the average output power and the pulse width. Therefore, a Transverse Magnetic Field Sweeping Solenoids(TMFSS) is designed. According to the simulation analysis of the electron distribution in the collector, the power density could be decreased significantly from 4.7 kW/cm2 to 0.29 kW/cm2 after applying the solenoids, which will effectively ensure the stable operation of the tube. The optimized design of the TMFSS will be used in the future gyrotrons assembly and hot testing.

Quasi-optical feed network can transmit multiple signals, which has been used in radio astronomy，atmosphere remote sensing and meteorological sounding. This paper describes the quasioptical design method，introduces the research progress in quasi-optical feed network and analyzes the development priority of terahertz quasi-optical. The research of quasi-optical components and high precision integration and test of quasi optical system will be the key point of future development.

The Orbital Angular Momentum(OAM) communication method is recognized as a promising method in improving the capacity of the communication systems. Based on the relevant research at home and abroad, the development of the OAM communications is introduced. According to the frequency characteristic, the structure and advantages of the terahertz OAM communication are analyzed. Some technical problems, especially those with wide bandwidth and long-range communications, are discussed for further development and applications.

The terahertz filter is an important component of the terahertz system, which is difficult to be designed quickly and accurately. Based on the co-simulation of Genetic Algorithm(GA) and finite element method, a fast and accurate design method of terahertz filter is realized. The HFSS-MATLABAPI script library is utilized in the design, which not only adopts the accuracy of HFSS for field simulation, but also reduces the blindness of tentative optimization by genetic algorithm in MATLAB. A 210-230 GHz band-pass filter is designed by this method. The measured results show that the in-band insertion loss is less than 0.6 dB and the out-of-band rejection is more than 30 dB. The accuracy of the method is verified.

Terahertz radar has extremely high resolution when measuring single targets. However, under multi-target conditions, the use of classical chirp waveform modulation may result in false difference frequency combinations, thus creating ghost targets. Aiming at this problem, a design scheme of multi-target detection for terahertz radar with improved waveform working at 0.22 THz is proposed. It consists of two parts:trapezoidal wave and triangular wave. The speed-distance blur range is calculated by the upper and lower sweep of the trapezoidal wave, and the relative speed of the target is detected by the constant frequency band. Nevertheless, the ghost target still exists owing to the mismatch of the velocity-distance intersection. The subsequent triangular waves with different frequency modulation slopes can help completely eliminate the ghost target. The architecture of the terahertz radar system is given in this paper, and through the near-realistic simulation, it is proved that the accuracy of terahertz radar for difference frequency pairing will be greatly improved under this new waveform system.

Analysis and pattern recognition of the interference undergoing in the communication system can assist the self-adaptive adjustment of the communication system parameters, thereby the anti-jamming capability can be stronger and targeted. A wide-bandwidth communication system is researched. Previous research shows that multi-hidden-layer neural network can resolve any form of classification problems. In order to classify the five common interference patterns, a classification method which uses power spectrum density and two-hidden-layer neural networks is proposed. Simulation results show that, under different interference patterns and different Interference-Noise-Ratios(INR), the average recognition accuracy is above 99.6%. In all the other four interference patterns without comb-spectrum interference, the recognition accuracy is above 99.7%, while 98.4% in the comb-spectrum interference. The proposed method has relatively stable recognition ability, and can be applied to the detection of communication interference.

The performance optimization of narrowband interference is discussed in view of two problems: the randomness of Global Positioning System(GPS) satellite signal and the cost of interference engineering. Firstly, on how to offset the randomness of satellite signals, the interference effects of different interference positions of single-frequency signals and narrow band Linear Frequency Modulation(LFM) signal bandwidth settings on GPS receivers are simulated and analyzed. Secondly, on how to reduce the cost of interference engineering, the method of replacing single interference with multiple interference is used for experimental analysis. The simulation results show that the interference uncertainty caused by the randomness of satellite signals can be eliminated to a certain extent by using the optimal interference position or the uniform and random distribution in the GPS signal bandwidth, and the total cost of interference can be reduced by replacing single signal with multiple signals.

The Joint North Sea Wave Project(JONSWAP) spectrum sea surface is mainly determined by parameters such as wind speed, wind area and spectral peak factor. The double stacking method is utilized to generate three-dimensional JONSWAP sea surface. The influence of direction concentration and spectral peak factor on the surface geometry model is analyzed. The physical optics method is adopted to analyze the changes of average backward scattering coefficient of JONSWAP spectrum sea surface with the direction concentration and the spectral factor. The simulation results show that the influence of spectral factor on the average backward scattering coefficient of the surface is less than 1 dB, and the influence of direction concentration parameters on the average backward scattering coefficient of the surface is more than 5 dB. Therefore, when studying the electromagnetic scattering of the JONSWAP spectral sea surface, the spectral peak factor can take the mean value, and the direction concentration parameter should be determined according to the wave growth state.

In order to be more adaptable to the upgrading of airborne equipment and enhance the capability of the fighters, the power management of airborne radar under active interference condition in air-to-air combat is researched from the pilots’ point of view. The effect of radar power management on electronic warfare interception is analyzed firstly. According to the numerical simulation results based on flight training data, the mismatch range of target Electronic Support Measure(ESM), the tracking range of the radar and the interception range by the target ESM compose geometric series. Then the relation between the mismatch range and burn through range is discussed. It is concluded that power manage measures should be taken on condition that the radar is superior to the target ESM obviously, otherwise the measures should not be taken in case of radar losing energy advantages over the target interference.

In view of the Point Spread Function(PSF) for near-field Multiple-Input Multiple-Output (MIMO) radar imaging cannot analyze the scattering mechanism of complex targets effectively, a simulation method of millimeter wave near-field MIMO radar imaging based on near-field Physical Optical(PO) scattering data is studied. The method uses near-field physical optics method to compute the near-field scattering field including the information of array configuration and scattering mechanism. Near-field MIMO image is finally generated by imaging processor. Using the D-band "T"-shaped two-dimensional sparse MIMO arrays to carry out the near-field imaging experiment, the simulation results are in good agreement with the actual imaging results. This method can analyze the imaging performance of the near-field MIMO imaging system, support the formation design, and reveal the near-field scattering characteristics and imaging mechanism of complex targets.

The detection and tracking process of radar targets are often interfered by ground clutters, sea clutters and whether clutters. After the traditional Moving Target Indication(MTI) filtering and Constant False Alarm Rate(CFAR) detection, the residual clutters have almost the same two-dimensional distribution(range-time) as the target, and it is difficult to distinguish them. To solve this problem, a plots filtering method for radar targets based on clutter feature evaluation is proposed. Synthetically considering the difference of features in amplitude fluctuation, distance/pitch/orientation correlation and phase shifts, comprehensive feature factors are evaluated to distinguish radar targets from clutters. Finally, the proposed method is verified by using the real radar measured data, which indicates that the effective suppression rate of clutters is significantly higher than that of traditional methods.

By synthesizing bandwidth in the frequency domain, the distance resolution of Stepped Frequency Radar(SFR) seeker can distinguish the detailed features of complex targets, so as to conduct anti-interference and target identification. When implementing SFR echo simulations, echo model are required to accord with the targets on detailed features, and the target is no longer point target. Nevertheless, using the scattering center extraction means some of the scattering points are discarded and merged, and the detailed description of the target is not accurate. Therefore, a method of generating complex target echo model based on FEKO is proposed, according to the time domain characteristics of the SFR signal, time domain echo model using the scattering data based on FEKO is deduced. In addition, FEKO is utilized to extract the scattering field amplitude and phase information of the target at various incident angles and the information is stored in database. When simulation is implemented, time domain echo calculation is conducted by directly employing stored scattering data, thus high fidelity echo model of complex target can be obtained. This method for echo modeling has practical value in air-to-air missile digital simulation, hardware-in-loop simulation and anti-jamming research.

For detecting and tracking the moving objects of interest by changing illumination, a new method is proposed. The proposed method combines improved Vibe algorithm with the particle filter algorithm by introducing illumination feeding model to Vibe algorithm, and reconstructing the particle filter to solve the changing illumination problem. In the phase of moving target tracking, Linear Regression Classifier(LRC) is introduced into the recognition algorithm, as well as the background information. The improved Local Ternary Pattern(LTP) is adopted to carry out feature extraction and recognition. Developing the program and carrying out some experiments, the experimental results demonstrate that the new method can assist detecting and tracking moving target with changing illumination study.

For the wireless cooperative location network using Ultra-Wideband(UWB) signal, a function model of the square position error bound of the network and the transmitting power of the agents is explored. Under the condition that the total power of the agent is limited, based on the Stackelberg model and the particle swarm optimization algorithm, the transmit power of the agent is optimally allocated. The simulation shows that the power optimization allocation proposed in this paper is more efficient than the power equal allocation. The square position error bound is reduced by 3%, which improves the positioning accuracy.

Aiming at the Wireless Sensor Networks(WSNs) of Duty Cycle(DC), the researchers have attempted to reduce transmission delay and energy consumption by Anycast technology, and have conducted in-depth research. An Energy Efficient Anycast Routing(EEAR) protocol is proposed in this paper. EEAR adopts a new Anycast routing metric called Expected Energy Consumed(EEC) that is contrary to previous Anycast routing metrics. By using the new Anycast routing metric, the forwarder set is selected reasonably and the expected energy consumed can be minimized along the path of a packet. Simulation results show that EEAR consumes less energy than similar existing protocols, while maintaining a comparable delay and high delivery rate.

A novel magneto–electric dipole antenna with ultra-wideband and dual-polarized characteristics is proposed. In comparison with traditional magneto-electric dipoles, this antenna achieves a wider bandwidth by replacing the traditional “Γ” feeding structure with a stair-shaped one, and meanwhile using semicircle radiators rather than the commonly used rectangular ones. Such an antenna is designed, fabricated and measured. The measurement and simulation results agree well with each other, and demonstrate encouraging properties. For its two feeding ports, the impedance bandwidths with the Standing-Wave Ratio(SWR)≤2 impedance are up to 90.8%(2.06-5.37 GHz) and 84.4%(2.08-5.12 GHz) respectively, and moreover, over the whole working frequency band, the proposed antenna possesses both good directional radiation patterns and stable gains, e.g. the gains are (8.6±0.8) dBi and (8.85±0.85) dBi respectively for the two feeding ports.

Based on the plane wave superposition model of the classical reverberation chamber, an improved plane wave superposition model is established in view of the fact that the existing probabilistic statistical model cannot simulate the environment of electromagnetic field with Rician distribution. In order to verify the validity of the model, the Probability Density Function(PDF) of the related electric field under different K factors is simulated by Monte Carlo method and fitted with ideal PDF. It is further verified that when the Rician K factor equals 0, the Rician distribution electromagnetic field model degenerates into a classical reverberation chamber field model. Finally, the influence of the sampling parameters(plane wave superposition number and agitator position number) on the simulation results is considered, and the best sample is determined to obtain stable PDF curve.

To meet the demand of high power microwave measurement, a broadband waveguide directional coupler of X-band is presented. In order to achieve the requirements of broadband, a multi-hole coupling structure is adopted, which uses the Chebyshev function to get each coupling coefficient, and gets the initial diameter of each hole by hole-coupling theory. A broadband coupler meeting the design requirements is obtained through optimization with simulation software. According to the simulation results, the coupling coefficient of the system is 40 dB within 8.2–12.4 GHz, the in-band fluctuation is less than 1 dB, and the isolation is more than 30 dB, the measured coupling coefficient is 38–39 dB, the reflection is less than -20 dB, the power capacity is 0.84 MW, which is suitable for MW level high power microwave pulse measurement.

A V-band miniaturized integrated receiving front-end mainly realizes the low Voltage Standing Wave Ratio(VSWR), low noise and miniaturization of V-band millimeter wave signal. In this paper, the miniaturized integration of millimeter wave receiver channel is realized by using multi-function chip and hybrid integration technology. A microstrip quadrature coupler is introduced to form a balanced distribution amplifier to optimize the input coefficient of the radio frequency receiving port, replacing the bulky waveguide broadband isolator, which reduces the volume and weight of the millimeter wave receiver front-end. Through the fault tolerance design of the transition probe of V-band waveguide, the assembly difficulty in the receiving front of the V-band is reduced, and the one-time assembly qualification rate of the front-end is improved. The input standing wave coefficient of the quantization V-band miniaturized integrated receiving front-end Radio Frequency(RF) is better than 1.6, the noise coefficient is better than 4.2 dB, and the external dimension(including the socket) is 33.4 mm×30 mm×12 mm. The V-band miniaturized integrated receiving front-end provides an effective solution for the integrated design and quantitative assembly production of V-band millimeter-wave miniaturization.

A simulation analysis method of harsh electromagnetic irradiation susceptibility about electronics is proposed aiming for high electromagnetic pulse attack in complex electromagnetic environment. This method combines 3D electromagnetic field simulation with 2D electric circuit simulation, which includes steps of building model, defining material parameters, adding load and exciting source, placing observation points. This method can obtain time-domain and frequency-domain characteristic of space and cable. According to the simulation results, the voltage and current in space and cable can reach peak soon with broad frequency domain, which are able to destroy many electronics. Therefore, some methods should be adopted to protect electronic devices. The proposed simulation method also can be utilized to analyze harsh electromagnetic irradiation susceptibility of all common electronics.

The basic transmission characteristics of Ultra Wide Band(UWB) nanosecond electromagnetic pulse signal via microwave receiver Band Pass Filter(BPF) is explored on time domain and frequency domain by using simulation calculation and experimental methods. It is the complement to the transmission characteristics study of traditional Continuous Wave(CW) signal and pulse modulation signal through microwave BPF. A preliminary law of transmission characteristics of UWB nanosecond electromagnetic pulse signal through microwave BPF is obtained, which can provide technical basis for the future applications of UWB nanosecond electromagnetic pulses in all kinds of receivers.

A novel circularly polarized rectenna with function of harmonic suppression is designed. The rectifier is directly integrated on the ground plane of the receiving antenna. The circularly polarized rectenna has the characteristics of light weight, compact size, low profile, and is easy to be conformed with the surface of aero-crafts. The rectenna works at 5.8 GHz and is fed by Coplanar Waveguide(CPW) coupling, which results in a broad working bandwidth. A Compact CPW Resonant Cell(CCRC) is directly loaded into the feeding to suppress the high order harmonics. The designed rectifier circuit adopts voltage doubling, and uses two chip capacitors for DC filtering and has a simple structure. The proposed rectenna has a compact structure and a 0.5 mm thick profile. Furthermore, the mass of the proposed design is only6.28 g and the optimum rectification efficiency is 63.84%. The test results are in good agreement with thesimulation results, which verifies the feasibility of the design.

The continuous Class-F Power Amplifier(PA) can mitigate the requirement of fundamental and second harmonic impedances by introducing a modified factor, thus extending the bandwidth of class-F PAs. In this paper, a new modified continuous Class-F mode is proposed. The design space is extended by introducing the resistive second and third harmonic impedance, so that it can realize multi-octave bandwidth. Based on this theory, an ultra-broadband high-efficiency power amplifier is realized showing 59%-79% drain efficiency,39.8-41.4 dBm saturation output power and large signal gain above 10 dB in 0.4-2.2 GHz frequency range. The simulation and test results are good, which verifies the validity of the methodology.