Xingchao Dong

DESIGN OF A DUAL-POLARIZED BROADBAND SINGLE-LAYER REFLECTARRAY BASED ON SQUARE SPIRAL ELEMENT

A dual-polarized broadband single-layer reflectarray antenna based on square spiral element is presented in this paper. Two designs with similar square spiral structures but different construction processes and transition patterns are investigated and compared. The comparison results show that the design varying the length of the first stub of one-arm square spiral is more suitable for building the reflectarray. Several 441-element reflectarray antennas fed by horn with different offset angles are also simulated and compared to show the broadband characteristic. A reflectarray with offset angle of 15 degrees is then fabricated and tested. The measured results show good radiation performances, and the 1-dB gain bandwidth of 34.7% is obtained. The measured gain is 27.1 dB at the center frequency of 15 GHz, which is equivalent to 45.6% aperture efficiency.

A novel single-layer reflectarray antenna using square spiral element

A novel single-layer reflectarray using square spirals is presented in this paper. The square spiral element employs four square spiral arms. By changing the length of the arm, a 450° phase variation range is realized. Besides, the element indicates stable responses for different incidence angles and the reflection phase curve is almost linear. Based on the good phase performance, a square reflectarray with side length of 99 mm is designed and simulated. The simulation results show good radiation performances and 1-dB gain bandwidth is about 31.3% at the center frequency of 15 GHz.

A novel seamless scanning leaky wave antenna in ridge gap waveguide technology

A novel seamless scanning leaky wave antenna in ridge gap waveguide technology is presented. The impedance matching technique is employed to suppress the open-stopband (OSB) which produces a discontinuity for a seamless scanning leaky wave antenna. Ridge gap waveguide proposed recently is used as the feeding structure. The antenna radiates from longitudinal slots of which the leaky constant is designed small to ensure a high directivity. The simulation results of full-wave analysis show that the proposed antenna bandwidth is from 12GHz to 18GHz covering the whole Ku-band while seamless scanning is achieved from backward to forward directions including broadside radiation. The scanning range is from −20° to 14° with an average gain of 18dB.

A new single-layer reflectarray using circular patch with semicircular ring slots

A single-layer reflectarray antenna using circular patch with four semicircular ring slots is proposed in this paper. By changing the diameter of the circular patch, the proposed phasing element can realize phase range about 500 degrees with relatively stable reflection magnitude. Besides, the reflection phase curve with smooth slope is almost linear. Based on the good phase response, a 421element reflectarray is designed, simulated and fabricated. The measured results show that 1.5-dB gain bandwidth can attain 24% at the center frequency of 15 GHz.

Design of a novel Ku/X-band reflectarray/transmit-array antenna with frequency selective surface

A planar reflectarray/transmitarray antenna which reflects/transmits the incident fields radiating from feed antenna is presented. The antenna works as a reflectarray at 13.85 GHz and a transmitarray at 8 GHz. The unit cell is composed of three layers. The first layer consists of a crosseddipole element and a square ring frequency selective surface (FSS) on the top and bottom surfaces of a dielectric substrate. The second and third layers are identical and consist of a square ring slot element on both sides of a dielectric substrate. An air gap is inserted between layers. The aperture of the antenna is 225 mm which equals 10.4 wavelengths at 13.85 GHz and 6 wavelengths at 8 GHz. The reflectarray/transmitarray antenna is fabricated, and NSI planar near-field system is used to measure the performances of the prototype. Good agreement between the simulated and measured results has been achieved. The measured gain is 27.1 dB in reflection mode at 13.85 GHz resulting in a 38% aperture efficiency and 23.1 dB in transmission mode at 8 GHz resulting in a 45.7% aperture efficiency.

Terahertz High-Gain Offset Reflector Antennas Using SiC and CFRP Material

Two high-gain terahertz (THz) offset reflector antennas are proposed. The silicon carbide material and thermally stable carbon fiber-reinforced plastic are selected as reflectors for high specific stiffness and low thermal expansion coefficient which are helpful for space use. Dual polarization is achieved by introducing a wire-grid polarizer which can separate the two THz polarization waves provided by multimode horns fabricated in electroforming technology. Furthermore, three-coordinate test system and theodolites are employed to detect the surface error of dishes and alignment of antenna subsystem. The physical optics analysis based on the measured reflector surface data is introduced referring to the large aperture antenna patterns by virtue of its accuracy and high efficiency. The results of this novel method are compared to that of the near-field test. Measurements show that the sidelobe levels (SLLs) of the single polarization silicon-based reflector are below −32 dB while the gain is 55.3 dB at 330 GHz, and the dual polarization carbon fiber-reinforced plastic reflector antenna suppresses the SLLs to −28 and −29 dB in two principal planes while the gain is 57.2 dB at the same frequency, respectively. The good performances of the proposed antennas indicate the potential for the application of space THz radiometer.

Three frequencies band dual polarization antenna for radiometer

This paper presents the design and development of a multifrequency finline orthomode transducer (OMT) and filters that separate the dual polarization waves. The wide band corrugated horn is used as the feed. Simulated results shown that the three frequencies (18.7GHz, 23.8GHz and 37GHz) patterns remain good shape, while the VSWR are lower than 1.5 at working bands.

A broadband reflectarray using patch with slot ring on ground plane elements

A broadband center-fed reflectarray antenna is presented in this paper. Patch with slot ring on ground plane elements are used for bandwidth improvement. It is shown that quasi-linear phase responses with broad frequency band can be achieved by such a phasing element. An 11×11 elements reflectarray is designed and simulated. The results show that the simulated gain is 23.92 dB at the center frequency of 13.58 GHz with 3-dB bandwidth of 52%, which demonstrate significant broadband operation compared with that of conventional reflectarray.