This paper gives an overview on current activities at Astrium GmbH in Friedrichshafen in the field of technology development for future space-borne X-SAR systems based on Digital Beam Forming. The focus is on the verification of scan-on-receive beamforming in the frame of the DLR funded “High-Resolution-Wide-Swath (HRWS) demonstrator” project.

ESA has initiated several studies to enhance the performance of next generation of C-Band SAR. This paper provides an overview of the on-going demonstration activity for critical technology in C-band as required for a next generation Sentinel-1 SAR instrument with enhanced performance in terms of coverage and resolution. The new instrument will use digital beam forming (DBF) capabilities to achieve the performance improvement by a new combined analogue/digital beam forming unit called TRIM (Transmit/Receive Interface Module). The paper reports on the status of ongoing developments at subsystem level including required technological elements as European GaN and deep sub-micron silicon semiconductor technology.

Since the U.S. Federal Communications Commission (FCC) opened the spectrum from 3.1 to 10.6 GHz for unlicensed radio applications with an EIRP of up to 41.3 dBm/MHz, numerous papers have been published on ultrawideband (UWB) antennas. Often the goal in these publications is to present an antenna, which has a satisfactory input reflection coefficient and a reasonable, constant radiation diagram versus frequency. However, in the case of UWB, there are numerous additional critical characteristics, which must be considered in the proper wireless system design. The publications, which treat this topic with sufficient proficiency, use such quantities as transient gain, group delay, ringing, dispersion, signal fidelity, polarization, efficiency, and the peak value of the transient response. For practical applications based on signals with an UWB instantaneous bandwidth occupation, all criteria are of vital importance, because they determine the sensor resolution, accuracy, or increase the bit error rate in communications systems. This paper gives an overview of UWB antenna designs together with their suitability for different applications with respect to the aforementioned critical characteristics. Additionally, UWB antenna array design, polarization diversity, and application in body area network (BAN) will be discussed. In nearly all cases the time-domain characteristics are taken into account, as they are more intuitive to interpret and very convenient for time-domain UWB system design.

Basic principles for ultra-wide-band (UWB) radiation are presented and discussed in this paper. The discussion starts with a description of the influence of antennas on UWB transmission. The parameters characterizing antennas in time and in frequency domain are specified. Since the number of possible antenna structures is nearly unlimited, the focus will be on a classification according to different radiation principles. For each of these mechanisms, the typical advantages and disadvantages are discussed, and an example antenna and its characteristics are presented. For a wireless engineer, the problem to solve is the proper design of an antenna with the desired radiation characteristics. The final outcome of this paper is that there exist numbers of UWB antennas, but not each of them is suited for any application, especially in view of radar and communication systems requirements.