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In this paper, a high-accuracy predistorter is proposed for digital predistortion (DPD) linearization of power amplifiers (PAs). This new predistorter is constructed by adopting an on-line cascade architecture to reproduce iterations of iterative learning control (ILC), which is an off-line iterative algorithm used to obtain predistorted-signal samples in the conventional ILC-based DPD. Experiments demonstrate that the proposed DPD method outperforms all the existing typical DPD methods, including indirect learning-based DPD, direct learning-based DPD, and ILC-based DPD.

Conventional full-band (FB) digital predistortion (DPD) methods have limited linearization performances in terms of the adjacent channel power ratio (ACPR) and normalized mean square error (NMSE) when the nonlinearity of power amplifier (PA) is considerably strong. In this paper, an out-of-band (OOB) DPD scheme is proposed for the PA with strong nonlinearity. This OOB DPD scheme only suppressing the OOB nonlinear distortion, and it significantly improves the performance of ACPR even in the context of strong nonlinearity. Experimental results verify that the proposed OOB DPD can improve the ACPR performance by 20 dB when the PA is driven to the strong nonlinearity of −25 dBc ACPR. Moreover, even if the PA is driven to −20 dBc ACPR where the PA reaches saturation on the signal peak, the proposed OOB DPD still effectively suppresses the partial OOB distortion by 19 dB.

During the operation of the isolating switch in the GIS, due to the relatively slow contact movement speed, multiple pre-and heavy breakdowns occur in the gap of the isolating switch fracture, resulting in steep traveling waves, and multiple reflections and superpositions occur at the discontinuity of the GIS wave impedance. And then very fast transient over voltage (VFTO)appears. The core question of this paper is an electromagnetic interference. This paper is about the measurement mechanism of three-dimensional transient electromagnetic field, and realizing three-dimensional magnetic field synthesis of single-point data collected on the spot. Then through the correlation analysis of the signal, it is demonstrated that when studying the frequency characteristics of the VFTO waveform, it can be decomposed into the theory of spectrum analysis of the VFTO pulse waveform of each breakdown, and then the breakdown signal is analyzed for the statistical characteristics and time-frequency spectrum analysis. It characterizes the characteristic analysis of the entire VFTO signal. The transient radiation field of GIS switch operation may cause strong electromagnetic interference to the online monitoring digital terminal. By studying the frequency components of transient voltage, it can play an important role in the protection of electromagnetic compatibility and smart grid EMC.

In this paper, a non-planar conformal dual-polarized phased array antenna is proposed. The design of non-planar conformal antenna and optimized simulations are presented. The antenna design is based on a dual-polarized patch antenna element with vertical orthogonal baluns. The antenna element is backed by a compact cavity, to reduce the inter-element mutual coupling and to enhance the scanning performance of the curved conformal array. The proposed array achieves a wide fractional bandwidth of over 20%, when scanning up to ±45° in E and H planes. The validity of design is confirmed by simulation outcomes of 10 × 10 array model.

A conformal half-Yagi antenna is proposed in this work which can realize the directional pattern along the axial cylinder metal carrier. The antenna is designed based on the monopole antenna and traditional Yagi antenna. The proposed antenna is composed of an active monopole, one reflector pole and three director poles which are designed on the ground plane according to the operation frequency range. The proposed antenna achieves a wide bandwidth of over 20% from 14 GHz to 18 GHz which broken through the bandwidth limit of the traditional Yagi antenna. The design and optimization for the antenna was conducted in this work, and the simulated results of the maximum gain is about 8.7 dBi in the direction 25 degree offset from axial. And the gain is about 5 dBi in the axial direction, the beam width is about 89 degree in the azimuth direction and about 32 degree in the elevation direction. The S 11 is less than −15 dB in the frequency range of 14 GHz to 18 GHz. The prototype of the antenna is fabricated by the NC milling process on a whole aluminum plate which can obtain the good mechanical strength performance. The measured results of the S 11 and the gain can agree with the simulated results. The dimension of the prototype antenna is about 50 mm × 30 mm × 10 mm, and the height of the prototype antenna protruding the surface of the conformal carrier is only about 5 mm. And the weight of the prototype antenna is about 14.8 g which is suitable for installing on the platform of conformal cylinder metal carrier which required the light weight for microwave communication.

In order to achieve high gain in the azimuth to cover 360-degree range., a distributed multi-beam antenna based on switch transformation technique is proposed. Each antenna can cover 45-degree range in the direction of azimuth (eight antennas cover 360 degree) and 30 degree in the direction of elevation., respectively. The light weight and low cost Aperture Coupled Microstrip Antenna (ACMSA) is designed to broaden the bandwidth of the traditional microstrip antenna. The CST MWS is used to simulate and optimize the antenna element. Based on the designed antenna element., an array antenna is introduced. The array antenna prototype is fabricated using PCB processing technique and the measurement for the array is conducted., the measured results show a good agreement with the simulation where the gain of the antenna is about 10.7dBi and the S11 parameter of the antenna is less than −10dB in the frequency range, respectively. 8 array antennas are assembled upon aluminum sustain structure to cover 360 degrees in the direction of azimuth and each array antenna can be selected by the switch to realize communication.