On Antenna-Architectures for Sensitive Radiometry to Support Oceanography

Paper in proceeding, 2015

The presentation discusses different antenna architectures supporting radiometric tasks for oceanographic observations. With Aquarius and SMOS in orbit with their associated resolution and revisit capability in L-band, further enhancements are of interest. Following studies into desirable resolution and frequency band interests for oceanographic applications (ref: Microwat - an ESA study, see also https://www.ghrsst.org/ ), breaking through and desirable requirements have been derived. Investigations into potential antenna architectural realisations have been initiated. Included are radiometer sensor (read:antenna) scenarios, based on conical scanning, interferometric 1D and pushbroom coverage. A wide coverage is available from the first two architectures, and a very good sensitivity is available with the pushbroom scenario. There are a couple of interesting aspects, related to polarimetry capabilities, resolution, sensitivity, etc. The pushbroom architecture, at cost of some complexity offers a very good sensitivity with interesting antenna architecture solutions to offer breaking through capabilities, in particular concerning the sensitivity requirements, in combination with polarimetric capabilities. Coverage comes with some infrastructural antenna complexity, with the needs and creativity for a deployable antenna configuration. Following initial considerations for all three antenna configurations at overview level, the push-broom scenario is presented with more details. Interesting aspects include ongoing technology developments in other related fields with refined results to come would enable to consider antenna architectures are used in which focal plane arrays find a combination with shaped reflector assemblies. With processing capabilities further enhanced - with ongoing developments underway in other sectors as radio astronomers can confirm - one would be able to further improve and refine sensitivity aspects in combination with polarimetric capabilities and resolution enhancement. Instrument sensors (read: antennas) have to be absolutely accurate, where in comparison telecommunication scenarios require a link budget to be fulfilled. The developments and availability of RF front-end and Analogue to Digital circuitry are an important aspect here, enabling the use of focal plane arrays with several hundreds of elements, as already ongoing within the radio-astronomy studies for the square kilometer arrays. Terrestrial applications in low power circuitries are ongoing in various domains, be it for local networks, sensor networks or other (various, IMEC, Fraunhofer, etc.). Further spin-in is expected. One could consider the resulting microwave push-broom antenna architecture in fact as a sensitive multi-frequency microwave camera, operating in frequency bands of interest. We are investigating currently the pushbroom scenario for 2, possibly 3 bands, from C-band up to Ku-band.