Antenna arrays on aircrafts have several advantages if they will be integrated into the skin of the aircraft. However, conformal and structure integrated antennas are subject to aeordynamical loads which will cause vibrations and deformations of the antenna elements. This will lead to severe deviations of the phase information of the incoming and outgoing signals and affects the antenna performance. One approach to overcome vibrations of an antenna array is active vibration control by integrating sensors and actuators into the antenna structure. This paper gives an overview of a demonstrator antenna array with active vibration control
-This paper presents two metamaterial-inspired solutions to mitigate the scan blindness effects in a phased array antenna. In the first solution, portions of a bed of nails are introduced in the radome to prevent the excitation of surface waves. In the second solution, a superstrate metasurface is designed to synthesize a permittivity tensor optimized to achieve a wide angle impedance matching. In both approaches, the numerical simulations are successfully compared with measurements of a phased array antenna prototype with 100 elements. The wire medium-based solution reveals an effective way for reducing the blind-spot in a wide bandwidth, while the metaradome has been found less suitable for the same purpose.
In this work, a metaradome based on a fakir's bed of nails is designed and tested in order to suppress the blind directions of a 100-element antenna array. The antenna is a microstrip array designed to operate in X-band. The fakir's bed metamaterial-like was first approximated using analytical formulas before a full-wave numerical optimization. Experimental results are exposed and confronted to numerical results. They show a significant reduction of the blind spot subsequent to the metaradome addition
A high gain vertically polarised travelling‐wave frequency scanning array antenna fed by a meander rectangular waveguide is presented for Ku‐band operation. The proposed antenna is used in a radar demonstrator setup to detect and monitor birds in direct proximity to the wind farms. The goal is to prevent collisions of birds with wind farms. The proposed antenna consists of 34 inclined dumbbell‐shaped radiating slots integrated with a parallel‐plate waveguide. The proposed meandered feeding structure is used to enlarge the beam scanning angle range over frequency. The dumbbell‐shaped radiating slots are employed in the narrow wall of the meandered waveguide due to the space restriction of the meandering. The parallel‐plate waveguide is used as a polarisation filter to reduce the cross‐polarisation level of the proposed antenna owing to the inclination of the radiating slots. An E‐plane horn is used to reduce the beamwidth in the elevation plane. The overall size of the antenna is 20.6λ in length and 15λ in width, where λ is the free space wavelength at 15.55 GHz. The antenna operates in the frequency range from 15.40 to 15.70 GHz. The half power beamwidth is about 4° in the azimuth plane and about 20° in the elevation plane at 15.55 GHz. The main beam of the antenna steers over frequency to cover 39° of angular range in the azimuth plane. A Taylor distribution is applied to achieve sidelobe level below −25 dB in the same plane and 26 dBi gain over the operating frequency range. The antenna array is fabricated and measured successfully to verify the proposed approach. The fabricated antenna shows an impedance matching significantly better than 10 dB in the operating frequency. The measured gain is higher than 25 dB throughout its frequency range.
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