Christian Trampuz

Interleaved Array Antennas for FMCW Radar Applications

An effective and robust strategy for concurrently designing the transmit and receive antennas of a frequency-modulated, continuos-wave radar is discussed. The aperture architecture is based on the use of non-periodic, interleaved sub-arrays. Deterministic element placement is employed for ensuring design efficiency. The procedure yields controllable sub-array radiation patterns and two-way side-lobe levels below - 30 dB, that are also stable over a wide frequency range.

Design, Analysis and Measurements of Reflected Phased Array Microstrip Antennas at Ka-band, using Hollow Phasing

The key issue in the design of microstrip reflectarray antennas is the technique used to obtain the required phase shift in the field scattered by each clement. Many solutions have been proposed in the past. Stub loaded patches, patches of variable size and patches with variable rotation angles are currently the most popular techniques. This paper introduces a different technique. The approach is based on identical patches with holes of different size to change the resonant frequency. This gives in turn a change in the phase of the reradiated field and allows directing the main lobe of the radiation pattern off broadside. The analysis was carried out at 33.5 GHz, first on a single element and then extended to arrays of finite dimensions. Some arrays were built and measurements were carried out on these prototypes. There is good agreement between theoretical results and measurements

A selection of meta sensing airborne campaigns at L-, X- and Ku-band

Synthetic Aperture Radar (SAR) is becoming more and more requested in the commercial and scientific world, especially considering the latest developments toward compact, high- resolution and cost-effective sensors. Since 2008, MetaSensing has been commercially offering services and sensors allowing a larger group of users to benefit from the advantages of SAR technology. During the last year of operation, MetaSensing has remarkably extended its radar capabilities by performing several airborne campaigns at different frequencies and interfer-ometric and polarimetric configurations. This paper reports about technical specifications of a selection of airborne data acquisitions at L, X and Ku band.

Antenna pattern measurements in the V-band — a low-cost test range

A simple and cost-effective test range for the measurement of antenna radiation patterns in the F-band is described. The arrangement enables accurate antenna measurements without resorting to the use of expensive anechoic chambers. A procedure for the alignment of the antenna phase center with respect to the rotation axis of the turntable, on top of which the antenna under test is fastened, is presented. The measurement procedure has been validated by comparing the measured radiation pattern of a standard-gain horn antenna with the results predicted by means of electromagnetic analysis tools.

Latest MetaSensing ground, airborne and spaceborne SAR developments

The paper focuses on the recent activities carried on by MetaSensing in the airborne, ground based and space borne SAR field. Several new sensors at different frequencies (including polarimetric and interferometric SAR at P, L, C, X, Ku band) have been built and operated by MetaSensing in different campaigns, the latest performed for private partners and agencies are described. MetaSensing is also involved in an innovative space mission study for a compact SAR satellite system. In addition to develop a space borne real time SAR processor, MetaSensing is carrying on Inverse SAR acquisition over the International Space Station and bistatic airborne measurements. Finally, the principles of the new developed Fast Ground Based SAR (FastGBSAR) are also described.

Low sidelobe interleaved transmit-receive antennas for FMCW radar applications

The advantages of interleaving the transmit and receive array antennas of an FMCW radar system in the same aperture were discussed. By dividing the real estate into sub-regions and applying to the two interleaved sub-arrays a thinning according to a Taylor illumination function, remarkably low sidelobes, below −40 dB for the radar two-way radiation pattern, were obtained. Some possible aperture partition alternatives were presented. Finally, it has been demonstrated that interleaving methodologies and thinning strategies can be proficiently combined to produce array factors with well-shaped beams and very low sidelobes.

Interleaved Array Antennas Design | (Almost) Deterministic Strategies

The synthesis strategies to be used for designing array antennas implementing the shared-aperture concept are described and discussed. The presented techniques range from fully deterministic approaches to semi-deterministic ones up to purely statistical design strategies. The pros and cons of each technique are ascertained. 1. INTRODUCTION The quest for increasingly performing antenna front-ends has been stimulated in the last years by the necessity of implementing complex functions in radars and communication systems. In particular, modern sensing systems require the (array) antennas to be able to perform a number of concurrent tasks, such as, for instance, operating at difierent frequency bands, difierent polar- izations, difierent scanning directions, etc. The coexistence of several array antennas performing concomitantly the difierent tasks often results in bulky antenna systems that are di-cult to deploy on moving platforms such as ships, airplanes or satellites. A convenient way to address this problem is to co-locate the array antennas responsible for the difierent services (functionalities) to be concurrently provided. The so-called shared-aperture concept (1,2) can then be adopted to realize multi-functional array antennas. The difierent func- tionalities are ascribed to sub-arrays of elementary radiators, the sub-arrays sharing a common physical area that constitute the complete antenna aperture. An early implementation of this concept is reported in (3) where the elementary antennas com- posing the sub-arrays are deployed on interleaved, uniform grids. A later contribution (4) proposed a complementary partition of a linear array in two sub-arrays exhibiting narrow radiation beams and grating lobes free operation. The shared-aperture concept was successively exploited to achieve multi-frequency operation (2) and polarization-agility capability (5). Moreover the possibility to integrate the transmitter and the receiver antennas of a frequency modulated, continuous wave (FMCW) radar by making use of the shared-aperture concept was demonstrated in (6). In this paper, some techniques that can be used to design interleaved array antennas imple- menting the shared-aperture concept are described. The reader is conducted through a path that, starts from strictly deterministic methods, passes through an intermediate step, and leads to fully stochastic approaches. The advantages and drawbacks introduced by the difierent techniques are analyzed in detail. It is worth noting that none of the techniques described in this work invokes any kind of iterative optimization procedure, this enabling a time efiective design strategy for any of the presented methods.

First results of the BelSAR L band airborne bistatic fully polarimetric Synthetic aperture radar campaign

BelSAR is an ESA funded project for acquiring and analyzing airborne bistatic Synthetic Aperture Radar data at L band, in support of the SAOCOM passive radar satellite under study at the agency. MetaSensing has built two L band SAR systems able to work in bistatic mode. A few test flights have been performed in The Netherlands and the paper reports the first results of the airborne bistatic campaign.

MetaSensing - the advanced solution for commercial and scientific SAR imaging

Synthetic Aperture Radar (SAR) [1] is becoming more and more requested in the commercial and scientific world, especially considering the latest developments toward compact, high-resolution and cost-effective sensors [3]. Since 2008, MetaSensing has been offering commercially services and sensors allowing a larger group of users to benefit from the advantages of SAR technology. During the last year of operation, MetaSensing has remarkably extended its radar capabilities by performing several airborne campaigns at different frequencies in interferometric and polarimetric configurations. The present article describes MetaSensings latest developments in airborne SAR imaging.