Cielo

Objectives

The primary objective of the Cielo project is to design and develop a fully functioning Ka Band transceiver at a competitive price point. The proposed new transceiver will offer significant cost savings when compared to the previous generation.

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This will be achieved by the following key changes to the product design:

• The transceiver will be a fully integrated product. A single base casting will be used for both the transmitter and receiver, and the OMT will be incorporated into this casting. Thus the number of waveguide interconnects will be reduced from 3 to 1. Also, some transmitter and receiver functions will be combined onto a common circuit board, reducing the number of PCB’s and reducing total size and component cost.

• Bare die used in the current BUC will be replaced by SMD’s. This will yield a pure SMD solution, allowing the use of board space to be better optimised. Also, employing SMD technology will allow the RF circuit boards to be manufactured using similar technologies to those used for Ku-band LNB’s, thus greatly reducing the manufacturing costs, compared to the current ‘chip and wire’ technology employed in the first generation products.

Challenges

Integrating transmitter, receiver and OMT into a single housing represents a significant step with associated technical risk. However this approach has already been proven in the Skyware industrialized Ku band transceiver, KR1214.

Whilst this fully integrated design has many benefits, there are also drawbacks. Principal among these is the heating of the receiver section by the high powered transmitter. This has meant detailed thermal design studies of the fins and mechanical housing.

The manufacturing and selection of appropriate filters will be one of the key issues to resolve in the manufacturing process.

The final key issue will be the achievement by the MMIC suppliers of a packaged chip suitable for SMD.

Plan

The initial part of the project, a concept design phase, has been completed. The key areas studied were: thermal design, filter concept design, electrical concept design and a MMIC packaging feasibility study.

With the completion of the electrical concept design, the overall radio architecture and likely board materials have been chosen. These have fed into the detailed electrical design of the five main circuit boards (TX RF, RX RF and IF).

With the conclusion of the MMIC packaging feasibility study, a decision has been made over what approach to adopt for packaging the MMIC’s.

Currently, the detailed design (mechanical and electrical) of the product has been completed. This development has included several iterations & trial integrations. 5 prototype units are in the process of being built and fully evaluated/tested.

Current Status

The 6 prototypes have been built and thoroughly tested and evaluated. The test reports are now available for review which will be held end May 2005.