Hendrik Bayer

Tracking antenna for mobile bi-directional satellite communications in Ka-band

A satellite tracking antenna for mobile satellite communications in Ka-band was developed, employing a conical scan produced with a tilted and fast rotating sub-reflector. This tracking technique facilitates a simple and low-cost dual-frequency feed structure suitable for bidirectional operation. Two separate tracking voltages are generated by the system — one for elevation and one for azimuth. The antenna is able to detect misalignments up to 2° from the satellite direction with a bandwidth of 20 Hz.

Ka-Band User Terminal Antennas for Satellite Communications [Antenna Applications Corner]

The growing need for bidirectional mobile satellite communications in the Ka-band necessitates the development of dedicated antenna systems. In this article, we describe two different solutions for mobile user-terminal antennas intended for an operation in emergency scenarios. The first solution, a high-gain antenna, consists of a Cassegrain reflector, fed from a multimode monopulse tracking system for circular polarization at a satellite downlink frequency of 20 GHz. The structure is operational at 30 GHz to cover the uplink frequency range. The antenna system is mounted on a high-performance mechanical positioner to facilitate a fast compensation of the movements of the carrier vehicle. The second solution, a low-profile antenna, consists of leaky-wave antenna (LWA) panels employing two-layer partially reflective surfaces (PRSs). A hybrid tracking technique is used, and a unique feature of this antenna is its dual-band operation, to overcome the challenge of widely separated uplink and downlink ranges in the Ka-band. This article describes the design of the two types of antennas and analyzes the measurement results. Furthermore, tracking issues considered from the view of control engineering are addressed, and an evaluation of tracking accuracy is presented.

A dual-band circularly-polarised leaky-wave antenna for mobile Ka-band satellite communications

This paper describes the design and testing of a circularly polarised dual-band leaky-wave antenna panel operating at 20 and 30 GHz. The compact panel fits into a low-profile user-terminal antenna concept intended for mobile bidirectional Ka-band satellite communications. As a proof-of-principle, a dual-band partially reflective surface (PRS) with a physical aperture of 60 mm by 60 mm was manufactured and tested. Numerical simulations and measurement results prove the principle of operation.

Low-profile tracking antenna for Ka-band satellite communications

This paper provides information about a mobile low-profile satellite tracking antenna with dual-band performance and a reconfigurable circularly polarised radiation pattern, realised by Ka-band sub-aperture panels located on a mechanical azimuth positioner. The design and measurement results of a leaky-wave antenna panel, selected for this purpose, as well as a tracking antenna prototype are presented in this publication.

Land-mobile Ka-band satcom tracking antenna employing a printed circuit board based multimode monopulse feed

The growing interest in bi-directional mobile satellite communications in Ka-band necessitates the development of dedicated antenna systems and feeds. In this paper we describe a mobile satellite communications ground terminal with a Cassegrain reflector antenna fed from a multimode monopulse tracking system for circular polarisation at the satellite downlink frequency of 20 GHz. The novel structure based on transitions from coplanar to circular waveguides is operational at 30 GHz as well, to cover the uplink frequency range. The antenna system is mounted on a high-performance mechanical positioner to facilitate a fast and precise compensation of the movements of the carrier vehicle. This work contributes to the development of a satellite terminal for land-mobile communications in disaster scenarios [1].

Dual-band leaky-wave antenna based on a dual-layer frequency selective surface for bi-directional satcom-on-the-move in Ka-band

A 2D-periodic leaky-wave antenna for a Ka-band satcom-on-the-move ground user terminal is presented. The antenna panel operates at the 20 GHz downlink as well as the 30 GHz uplink bands with the respective circular polarizations, using a common radiation aperture and a common phase centre. The dual-band performance is achieved by a carefully designed stacked dual-layer frequency selective surface, with one layer operating at 20 GHz and being transparent at 30 GHz, and the second layer acting vice versa. The paper describes the design of the circularly polarized primary feed, the dual-layer structures, and the complete compact leaky-wave antenna panel. The measured radiation performance reveals realized-gain values above 22 dBi and efficiencies above 60%. The cross-polarization discrimination and sidelobe level are suitable to meet the power spectral requirements for satellite communications at Ka-band.