Single Feed per Beam

Status

Completed
Status date

2010-12-09
Activity Code

5C.225

Objectives

The project covers the development, manufacturing and test of two types of Ka-band feed chains. The feed chains are assigned to work in a single feed per beam multi spot beam antenna. They are dual circularly polarized and combine Rx and Tx signals. One feed chain serves user and gateway applications, the other feed chain additionally provides RF sensing capability.

Current Ka-band multi spot beam antennas are using different feed chain designs for User, Gateway and RF sensing (RFS) applications. The varying positions and orientations of the RF I/F's of the different feed chains require a quite complex waveguide routing to connect the feed chains to the RF P/L I/F's at the spacecraft module. Beside the efforts in producing and accommodating these individual waveguide runs they simultaneously increase the complexity of the thermal design of the feed cluster assembly.

The objective of this development was to design, build and test an EM of each a generic feed chain for User and Gateway applications as well as a feed chain for RFS applications, all of them having standardised RF I/F's in a regular configuration and orientation. This will allow for the deployment of a simplified and modular waveguide run design, thus considerably reducing production or procurement cost and lead times and simplifying the thermal design of the feed cluster assembly.

Furthermore a novel mode filter concept in the common Tx/Rx section of the feed chain avoids the use of any waveguide filters or diplexers in the feed chain network, thus increasing the operational band width of the feed chains.

Challenges

Generic design for User and Gateway feed chain,
To be build with fast and conventional manufacturing technics (due to possible high nuber of required feed chains),
Standardised RF I/F's,
Novel feeding concept:
- Increased frequency bandwidth,
- Reduced Ohmic losses,
- Improved axial ratio.

Benefits

Increased antenna gain due to reduced losses,
Improved XPD due to reduced axial ratio,
Reduced manufacturing / procurement cost and lead time of feed cluster assembly due to modular and standardised design,
Capability of tracking of CP as well as LP beacon signals.

Features

Generic user and gateway feed chain design with standardised RF I/F's
Tracking with E01 mode - alternatively using two orthogonal delta modes to enable for tracking of CP as well as LP beacon signals
Combined Tx/Rx operation over an increased frequency bandwidth:
- Tx: 17.7GHz - 20.2GHz
- Rx: 27.5GHz - 30.0GHz
- Dual polarized (RHC/LHC)
- Axial Ratio < 0.30 dB
- Ohmic losses UG Feed Chain
  - Tx < 0.35 dB
  - Rx < 0.25dB
- Ohmic losses RFS Feed Chain
  - Tx < 0.45 dB
  - Rx < 0.2 dB
Generic design: all components of the feed chains remain unchanged for different applications. Only the horn has to be adapted.

Plan

This Artes 5.2 project:

Design, manufacture and test an EM of a generic User and Gateway feed chain,
Design manufacture and test an EM of a RFS feed chain.

Continuation under a joined Artes34 project together with Astrium Ltd:

Manufacture and test a batch of EQM User and Gateway feed chains and a RFS feed chain,
Design, manufacture and test an EQM of a feed cluster housing module (FCHM),
Integrate and test the EQM of the feed chains and FCHM assembly.

Finalisation in November 2011.

Current status