16, August 2019

ESA Open Invitation to Tender AO9924
Open Date: 14/08/2019
Closing Date: 02/10/2019 13:00:00

Status: ISSUED
Reference Nr.: 19.1ET.21
Prog. Ref.: Technology Developme
Budget Ref.: E/0901-01 – Technology Developme
Tender Type: C
Price Range: 200-500 KEURO
Products: Satellites & Probes / RF / Microwave Communication (Platform and Payloads) / Antennas / Omnidirectional, Helix, Horn, Parabolic, Phased Arrays / Platform vs Payload
Technology Domains: Electromagnetic Technologies and Techniques / Antennas / Array Antennas and Standalone Radiators
Establishment: ESTEC
Directorate: Directorate of Tech, Eng. & Quality
Department: Electrical Department
Division: RF Payloads & Technology Division
Contract Officer: Singer, Anze
Industrial Policy Measure: N/A – Not apply
Last Update Date: 14/08/2019
Update Reason: Tender issue

Most of the sub-surface planetary radars operate in the frequency band between 6 and 50 MHz. At these frequencies, and due to the large size of the antennas, a trade-off is made on the centre frequency and bandwidth of operation based on the science requirements of depth and resolution. The reason for this is that a resonant dipole antenna operating at a higher frequency out of resonance willgenerate nulls in the nadir direction, yielding a great loss in dynamic range and thus in penetration depth. The only alternative available today would be to accommodate multiple antennas for various frequency bands, with the direct consequence of risky deploymentschemes and significant increase of cost and mass. This activity is focussed on the development of a single dipole antenna that canbe used in a large frequency band (e.g. 9-30 MHz) for EnVision. Several techniques have been identified that can be used to achievethese results: a design based on lumped elements (inductances and capacitances) that at higher frequencies become high impedances and thus electrically reducing the size of the dipole, generating this way the wanted smooth pattern towards nadir, without loss of dynamic range. The same lumped element at low frequencies lets the current pass and the whole length of the dipole is used, to obtainthe same type of radiation pattern. Alternatively, a telescopic boom can also be used as antenna arm, and through the change of thelength of the dipole during flight, observation at different centre frequencies throughout the mission becomes possible. The mechanism and deployment of telescopic CFRP boom is already available in Europe with flight heritage. The existing transmitter and receiver units have already the capability to operate in multi-mode (including changing the centre frequency of the chirp and its bandwidth), but no antenna is available to enable such operation. This activity will start with a trade-off of the available techniques to achieve multi-band operation of the dipole and after selection of the most suitable methodology, design, manufacture and test a working breadboard of the selected concept

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