1 A. Reflector Antenna
Reflector antennas are widely used in radar, communication, remote sensing, radio astronomy and other fields. However, with the development of modern reflector antennas towards large aperture and high frequency, it is more difficult to ensure their surface accuracy. Therefore, lots of work has been done to ensure their electrical performances from the coupling relationship between structural error and electrical performance [3]. But how to ensure the electrical performance of the antenna from the aspect of electromechanical coupling is the content that we want to present in the following.
The main factors related to the electrical properties of reflector antennas are panel deformation, feed position and attitude, etc. In practice, external loads such as gravity, wind and temperature will lead to the reflector panel’s deformation, feed position offset and attitude deflection, which affect the electrical performance.
In order to express the influence of these mechanical factors on electrical performance, the electromechanical coupling model is established as follows [4]:
where k is the air propagation constant; \(f_{0} (\xi - \Delta \xi (\varvec{\delta}(\varvec{\beta})),\phi^{\prime} - \Delta \phi^{\prime}(\varvec{\delta}(\varvec{\beta})))\) is feed pointing error on aperture field amplitude; \(\varphi_{f} (\varvec{\delta}(\varvec{\beta}))\) is feed location error on aperture field amplitude; \(\varphi_{s} (\varvec{\delta}(\varvec{\beta}))\) is panel distortion on aperture field phase; φ r (γ) is panel machining accuracy on aperture field phase; \(\varvec{\beta}\) is structural design variables including size, shape, topology, type etc., and γ is manufacturing process factor.
The electromechanical coupling model has been applied to a 66 m antenna structural design, which achieves the optimal stiffness distribution of the back-up structure and the center body, improves the structural symmetry and reduces the system failure risk. Ultimately, the gain of antenna increases by 0.4 dB, the sidelobe level decreases by 1.2 dB, and the weight decreases by 8%.