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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.

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This paper describes the design of a novel test-set for single-ridged waveguides in the 28.5 GHz band. The test-set composes of three main parts: a waveguide transformer with a 900 bend,a part of an antenna array (slots) represented by a ridged waveguide transmission line and a load. The transformer provides a single-ridged-waveguide-to-standard-WR-28 transition and vice versa. This transition forms the interface to the measurement equipment and parts of its design will also be applied to the original design of the antenna. The load can be tested by connecting it to the singleridged output port of the adapter or to the waveguide transmission line. This saves precious development time and costs, and enables also an accurate verification of the adapter design. The waveguide transmission line can be used to test different slot configurations. Some simulations have been performed to investigate the tolerance values required for manufacturing the test-set.

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Millimetre wave antennas are typically used for applications like anti-collision car radar or sensory. A new and upcoming application is the use of 60 GHz antennas for high date rate point-to-point connections to serve Wireless Local Area Networks. For high gain antennas, configurations using lenses in combination with planar structures are often applied. However, single layer planar arrays might offer a more cost-efficient solution, especially if the antenna and the RF-circuitry are realised on one and the same substrate. The design of millimetre wave antennas has to cope with the severe impacts of manufacturing tolerances and losses at these frequencies. Reproducibility can become poor in such cases. In this paper, the successful design and realisation of a cost-efficient 60 GHz planar patch array (8x8 elements) with high reproducibility for point-to-point connections is presented. Important design aspects are highlighted and manufacturing tolerances and losses are analysed. Measurement results of different prototypes are presented to show the reproducibility of the antenna layout.