Active phased array antenna (APAA) is a representative of complex electronic equipment, and it plays significant roles in scenarios such as battlefield situation perception, aviation guidance, and communication. It has become the core equipment in land, navigation, and aeronautical applications. With the continuous improvement of technical changes and military requirements, the working frequency band, pointing accuracy, gain, and low sidelobe level of APAA increase, and the multi-disciplinary design contradiction between antenna electrical performance and structure and temperature becomes increasingly prominent. As a result, the electrical performance of APAA in service is prone to be affected by the external complex environments. The structural-electromagnetic-thermal (SET) coupling problem has become a key problem restricting the development of APAA. This paper has summarized the structural features and environmental loads of advanced APAA on different platforms and provided design basis and principle for antenna designer. And then the SET coupling theory of APAA has been introduced, which can be applied in both the design and manufacturing stage, as well as the performance control technology in service environment of APAA. This theory helps to analyze the impact of environmental factors, such as antenna structure deformation, radome high-temperature ablation, and feed errors, on the antennas performance. For 128768 spaceborne array antenna, in the range of 2585C, the gain of antenna decreases with the increase of operating temperature and decreases by 0.015dB with each increase of 1C. The key design parameters in the fields of antenna manufacturing accuracy, efficient heat dissipation, and lightweight design are also analysed; for 3232 rectangular planar phased array antenna, the gain of antenna decreases by 2.715dB when the random error of installation position in x, y, and z direction reaches 1/10 of the wavelength. In addition, condition monitoring, displacement field reconstruction, and electrical performance compensation of APAA have also been touched to help engineers maintain and guarantee the antenna performance throughout its life cycle. Finally, the future research direction of SET technology of APAA has been discussed, and SET technology is extended to more fields such as antenna parameter uncertainty, high-frequency circuit electronics manufacturing, and electronic equipment performance guarantee.

The application of intelligent algorithm in reconfigurable antenna design can break the inefficiency of traditional antenna design based on engineering experience and electromagnetic simulation software and can significantly improve the intelligent level of antenna design. However, the convergence rate, global search ability, and optimization accuracy of the intelligent algorithm seriously restrict the accuracy and automation efficiency of antenna design and have become the bottleneck of reconfigurable antenna rapid intelligent design. Therefore, an adaptive immune annealing algorithm (AIAA) for rapid design of reconfigurable antenna is proposed in this article. AIAA introduces the idea of adaptive crossover and mutation into the basic immune algorithm (IA), which improves its population update strategy and improves the convergence rate of the algorithm; moreover, simulated annealing (SA) operator is added to the improved IA, which enhances the global search ability of the algorithm. The standard function test results show that compared with the basic IA, AIAA improves the convergence rate, global search ability, optimization accuracy, and robustness. Finally, based on AIAA, a design scheme of frequency and pattern reconfigurable antenna is proposed. Frequency reconfigurable antennas with resonant frequencies of 8.58 GHz ( $X$ -band) and 15.83 GHz ( Ku -band) and pattern reconfigurable antennas with maximum radiation directions of +39° and −39° in the xoz plane are designed based on this design method, and experimental tests are carried out. The accuracy and effectiveness of the AIAA in the design of reconfigurable microstrip antenna are verified.

Structural deformation caused by environmental loads (solar irradiation, snow and ice, devices heat dissipation, etc.), could severely deteriorate the performance of high-frequency large-aperture active phased array antenna (HLAPAA). The existing sensor placement methods for monitoring the real-time status of HLAPAA have issues with slow convergence rate, limited global search ability, and low optimization accuracy, especially with large HLAPAA with tens thousands of degrees of freedom. In this paper, we propose a novel HLAPAA sensor placement method with an adaptive double population grey wolf optimizer (ADGWO). This method introduces adaptive sentinel wolves into the basic grey wolf optimizer (GWO), improves the population update strategy and thus improves the convergence rate plus the global search ability. First, based on four benchmark functions, the test performance of ADGWO and other popular intelligence algorithms is provided. The comparison shows that the proposed method has excellent convergence speed, higher solution quality, stronger global search ability, and better robustness, making it suitable for optimal sensor placement (OSP) of large structures. Then, the ADGWO is applied to the sensor placement of an X-band HLAPAA. Compared with other OSP methods, the proposed method has advantages in terms of sensor distribution and computational and hardware cost. Finally, verification is carried out using an experimental antenna platform equipped with the optimal fiber Bragg grating (FBG) strain sensor configuration. The measurement results show that the reconstructed shape is in good agreement with the real (deformed) shape, and the calculated radiation pattern matches the radiation pattern measured in the anechoic chamber. Therefore, the proposed method and monitoring system based on ADGWO has broad application prospects in condition monitoring of large, lightweight, flexible antenna structures working in harsh environments.

This paper investigates the deformation reconstruction of vehicle-mounted radar antenna in harsh environment. With the fiber Bragg grating (FBG) strain sensor, an online radar antenna monitoring system is designed. This system simulates the typical or actual wind load of an antenna array and reconstructs the deformation shape of the antenna structure using measured discrete strain. Moreover, a new strain-displacement transformation relationship modified method, with the measured information of structure deformation and strain, is presented, and thus the accurate displacement evaluation of the antenna structure is completed. The method is divided into three steps: 1) under typical wind loads, the radar displacement and strain data are collected; 2) in combination with the least squares principle, the error matrix of strain-displacement transformation relationship is solved; 3) the error matrix is utilized to modify the strain-displacement transformation relationship. Finally numerical simulations are conducted, and the comparisons show that the proposed method is more superior in terms of the reconfiguration accuracy. Experimental validation performed using an antenna experimental platform equipped, with FBG strain sensors shows that the reconstruction results in excellent agreements with those measured directly from high accuracy digital photogrammetry.

With the constant increase in communication requirements in modern society, the number and type of antennas on communication platforms have been increasing at an accelerating rate. This has led to a continuous increase in platform volume and weight, and the electromagnetic environment of antenna operating has increasingly worsened, seriously restricting the further development of communication systems. As a new communication system antenna type, a reconfigurable microstrip antenna can reconstruct operating frequencies, beam directions, etc., by changing the antenna structure to provide the good multifunction characteristics of a single antenna, avoiding the electromagnetic compatibility issues caused by numerous system antennas. At present, most of the research on reconfigurable antennas judges the influence of structural characteristics on electromagnetic characteristics by simulation, which has imposed restrictions on their development and application. Therefore, a reconfigurable antenna with a resonant frequency of 8.66 GHz and 15.26 GHz and a reconfigurable antenna with maximum radiation directions of 36.2° and −36.5° are designed in this paper, and the electromechanical coupling theory of the reconfigurable antennas is studied. The resonance frequency coupling model and the pattern function coupling model considering the structural deformation of a reconfigurable microstrip antenna are established. Within the applicable range of antenna structural parameters, the relative error between the resonance frequency coupling model and the pattern function coupling model is less than 5%, which meets practical engineering application requirements. Finally, the method is shown by experimentation to verify the accuracy and validity of the proposed electromechanical coupling model.

Radar detection equipment with active phased array antennas (APAA) as signal transceiver is an important part of modern communication and military warfare, while the various uncertainties arising from the manufacturing assembly and operating environment of the antenna have a substantial impact on the detection performance of active phased array radar. Consequently, it is essential to examine the influence of these uncertainties on radar detection capability and explore robust strategies for performance regulation. This paper takes the APAA with antenna detection as a function as an object, the deviation analysis of antenna gain, sidelobe level and half-power beamwidth on the maximum detection range is realized, the interval amount calculation formula of ranging and angular detection accuracy is derived, and the influence of half-power beamwidth on target resolution is analyzed. Then an APAA performance guarantee method based on interval refinement is proposed. The proposed method is validated by comparing its compensation results with those of conventional optimization algorithms, revealing clear advantages in both computational efficiency and compensation accuracy. A case study is conducted to evaluate the performance of the proposed method, and the results show that the proposed method can effectively reduce the interval size of the amplitude and phase compensation of the excitation current and significantly improve the antenna detection performance.