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The OVP blended teaching method is an effective teaching method based on the engineering teaching practice and the course system of microwave technology and antenna. In the teaching process, we should emphasize the combination of network, virtualization and project teaching mode, and attach importance to the application of new educational platform and educational resources, especially the diversification and cutting-edge concept of curriculum team, which makes teaching methods diversify and engineering. A number of knowledge points throughout the whole design process, to achieve the effective combination of technical principles and engineering practice. It enables students to really participate in the process of teaching and learning, and help to cultivate their comprehensive abilities of practice and innovation.

We propose a novel method of background suppression to solve the issue that background regions are recognized as actions in weakly-supervised temporal action localization. The general attention-based action localization methods tend to use the attention module to generate segment-level attention weights. But there is little difference between the attentions from the background segments similar to the target actions and the attentions of the action segments, which causes the result that many background segments related to the target actions are still recognized as actions. To address this issue, a weakly-supervised temporal action localization network by background suppression (BS-WTAL) is designed. It introduces a filtering module for suppressing the background features and encouraging the action features, a classification module for identifying action categories and a generative attention module for segment-wise representation modeling. This enables BS-WTAL to suppress background to improve localization performance. Furthermore, we conduct ablation studies from different perspectives. Extensive experiments were performed on two datasets – THUMOS14 and ActivityNet1.2. Our approach shows better performance on these two datasets, even comparable with state-of-the-art fully-supervised methods.

An ultra-wideband 45° phase shifter is presented in this letter. The phase shifter is designed using a multi-section broadside coupling structure that yields ultra-wideband bandpass response and constant phase shift. The measured reflection coefficient, insertion loss and phase variation are −12.5 dB, 0.67 dB, ±1.6° for the band from 2.85 to 10.70 GHz (112%), and −12.5 dB, 1 dB, ±5° for the band from 2.60 to 11.05 GHz (124%). This design outperforms the previously reported results about ultra-wideband 45° phase shift and is suitable for the ultra-wideband Butler matrices design.

Path planning is a prerequisite task to automatically navigate with virtual camera and plays a crucial role in virtual endoscopy (VE) application. The path planning algorithm based on segmentation combines the center-line path with the image segmentation by using the result of image segmentation to reduce the complexity of path planning. The algorithm makes use of the connectivity-preserving features of sequence images and segments a series of images by applying the adaptive region growing algorithm. It stores the seed of growing region into a series of stack as the key point of the navigation plan. Considering there are maybe some cavities after 2D segmentation, we propose a 3D region growing algorithm. The key point of navigation path is selected during segmentation, and the navigation path is obtained after smoothing those points. Experiment results show that our algorithm is feasible and robust.

A novel centerline planning algorithm for virtual endoscopy is proposed. It can be executed in original images data directly, no longer subjects to the results of segmentation. It is based on B-Snake model, and a moving polyhedron centralize method is defined, which provides a centralizing force as the external force of B-Snake model. And the internal force of the Snake model is removed, so as to control the model easily. With the characteristic of B-spline, a few control points are chosen and the smooth and continuous centerline is got effectively. Error analysis and experimental results show the validity of the proposed method.

Recently, metasurfaces (MSs) have continuously drawn significant attentions in the area of enhancing the performances of the conventional antennas. Thereinto, focusing MSs with hyperbolic phase distributions can be used for designing high-gain antennas. In this chapter, we first design a new reflected MS and use a spiral antenna as the feeding source to achieve a wideband high-gain antenna. On this basis, we propose a bi-layer reflected MS to simultaneously enhance the gain and transform the linear polarization to circular polarization of the Vivaldi antenna. Then, we proposed a multilayer transmitted MS and use it to enhance the gain of a patch antenna. This kind of high-gain antenna eliminates the feed-block effect of the reflected ones but suffer from multilayer fabrication. To conquer this problem, we finally propose a single-layer transmitted focusing MS by grouping two different kinds of elements and use it to successfully design a low-profile high-gain antenna.

Fabry-Pérot cavity (FPC) antenna is a kind of high-gain antenna. Compared with other high-gain antennas, such as array antenna and reflector antenna, the FPC antenna enjoys the advantages of simple structure and high efficiency. So it has attracts many attention since proposed. However, it also suffers the disadvantages of narrow band and fixed radiation patterns, due to its resonance structure. In order to overcome these disadvantages, we proposed novel strategies to realize reconfigurable FPC antennas using the phase controllable metasurfaces (MSs). Through adding PIN diodes into every unit cell of the MS, the reflection phase of the MS can be controlled by tuning the states of the diodes. Then the designed phase controllable MSs are used as the partially reflection surfaces (PRS) to realize frequency or radiation pattern reconfigurable FPC antennas. In this chapter, we analyze the basic theory of the FPC antenna and describe its radiation principle firstly. Then, reflection phase controllable MSs are designed and applied to the FPC antennas. Thus frequency and radiation pattern reconfigurable FPC antennas are formed. The design processes are described in details, and the proposed antennas are fabricated and measured. The measured results verify the correctness of the designs. Through this chapter, the readers can form a comprehensive understanding of reconfigurable FPC antenna design.

Recently, metasurfaces (MSs) have received tremendous attention because their electromagnetic properties can be controlled at will. Generally, metasurface with hyperbolic phase distributions, namely, focusing metasurface, can be used to design high-gain antennas. Besides, metasurface has the ability of controlling the polarization state of electromagnetic wave. In this chapter, we first propose a new ultrathin broadband reflected MS and take it into application for high-gain planar antenna. Then, we propose multilayer multifunctional transmitted MSs to simultaneously enhance the gain and transform the linear polarization to circular polarization of the patch antenna. This kind of high-gain antenna eliminates the feed-block effect of the reflected ones.