Peng-Khiang Tan

Low-Profile, Wideband Dual-Polarized Antenna With High Isolation and Low Cross Polarization

A wideband dual-polarized antenna with high isolation and low cross polarization is presented. A pair of orthogonal planar printed dipoles, with a reflector ground plane, are used to obtain the two linear polarizations. Slots cut at the dipoles corners and shorted connections between the orthogonal dipoles are used to improve the isolation and cross polarization. Measured results show that the antenna achieves a VSWR <; 1.5 from 575-722 MHz (22.7% bandwidth). The isolation between the two polarizations is better than 35 dB, and the cross-pol level is 30 dB below the co-pol level over the entire band. The overall height of the antenna is 80 mm, which is about 0.15λ at 575 MHz.

Investigations on bandwidth improvement of reflectarrays using single-layered sub-wavelength double circular ring elements

In an effort to improve the bandwidth of the single layer reflectarray, this paper investigates the use of double concentric circular ring elements arranged in a range of sub-wavelength grids on a single layer of substrate. The double concentric circular ring elements used here allow an additional degree-of-freedom to improve the bandwidth. Based on the concentric ring element, four offset-fed 0.43m×0.43m (14.3λ×14.3λ) reflectarrays centered at 10 GHz with various element periodicities, namely λ/2, λ/3, λ/4 and λ/5 grids, are designed and developed. The measured results show that among the four reflectarrays, the one with λ/4 grid spacing achieves the broadest 2-dB gain bandwidth of 33% with an aperture efficiency of 36.2%.

Beam-scanning improvement of reflectarrays using single-layered sub-wavelength elements

This paper studies the use of double concentric circular ring elements arranged in a sub-wavelength grid on a single layer of substrate, in an effort to enhance the beam-scanning capability of reflectarrays. The work is carried out at 10 GHz on a 405mm×405mm aperture. In addition to a broad gain bandwidth, the reflectarray with a sub-wavelength grid demonstrates a superior beam-scanning performance compared to the one with X/2 grid. The measured results show that the reflectarray with 0.3X grid spacing realizes a 1-dB gain bandwidth of 22% with an aperture efficiency of 56.6%. With the reflectarray fixed, this paper investigates the possibility of beam scanning by displacing the feed horn laterally. The results show that beam scanning of ±15o is possible while retaining the broadband characteristics.

Compact and wideband antenna array

A novel wideband patch pair array antenna is presented. This array has a simple structure, compact in size, and wide bandwidth. The simulated and measured results show that return loss less than -10 dB from 2.8 GHz to 5.8 GHz. The radiation patterns are good throughout the whole frequency band.