Phased array using the sequential rotation principle: analysis of coupling effects

Abstract

The growing demand for broadband multimedia services urges the aeronautical industry to provide bidirectional on-board communication services in near future. Today, the first aircrafts are already being equipped with the technology necessary to provide intemet access for staff and passengers. Up to now, these solutions are developed to operate in L-and Ku-Band, due to the satellite systems available and the existence of affordable RF-components for these frequency ranges. Considering broadband multimedia applications, however, it is obvious that in the near future the technology will have to explore higher frequency regions like Ka-Band, where the required bandwidth can be provided. Several studies show that, for airbome broadband satellite communications, the terminal antenna is one of the key components in the system design. To compensate for the aircrafts movement, the terminal antenna must be steerable, to allow satellite tracking. Due to the limitations of mechanically steerable antennas, an electronically steerable array antenna using digital beamforming seems to be the most promising solution. Still, the development of such antenna arrays in Ka-Band technology faces high demands regarding performance, integration and, last but not least, component costs. In the framework of a project called SANTANA (Smart ANtenna TermiNAl), funded by the german government (BMBF) on behalf of the DLR, several antenna concepts have been investigated. One promising concept, which will be discussed in this paper, is a transmit-only array at 30 GHz that uses the sequential rotation principle to improve the circular polarisation.

Far-field characterisation of large arrays: A methodical approach

“…Investigations showed that this is allowed for the respective configuration because the amount of surface waves propagating is very small [6].…”

Sequential 90° Rotation of Dual-Polarized Antenna Elements in Linear Phased Arrays with Improved Cross-Polarization Level for Airborne Synthetic Aperture Radar Applications

“…Some other techniques improve the cross-polarization level by rotating the antenna elements in reflectarray applications [23], or combining the 180°rotation of the antenna structure along with a 180°alternate feeding based on the overlapping of different multipolar moments [24]. Further rotation topologies such as the sequential rotation is typically used for arrays of circular polarized antennas, as it leads to an improvement of the axial ratio bandwidth or the polarization purity [25][26][27][28][29]. Generally, the majority of cross-polarization suppression techniques start from the decomposition of planar arrays into subarrays, and a very few applications consider linear arrays.…”

Low Side-Lobe Circularly-Polarized Phased Arrays Using a Random Sequential Rotation Technique

“…Next to the challenge of generating high-quality circular polarization, there is the issue of side-lobe control. Regular (periodic) array antennas experience a limited frequency bandwidth due to the appearance of grating lobes and blind scan angles that are due to the element separation distance and mutual coupling [8], [9]. In addition, such arrays typically do not allow for dual-frequency operation.…”