The objectives of the project are to design and manufacture an engineering model (EM) of a GNSS receive antenna for in-orbit position determination of telecommunication satellites in geostationary orbit (GEO). The design tasks shall cover two single frequency antennas with right-hand circular polarisation (RHCP), GNSS receive antennas, respectively tuned on the L5/E5a- and L1/E1-bands. One single frequency antenna shall be selected for manufacturing on basis of criticality of the respective design. The antenna manufactured is to be characterised by measurements on EM level.
The key challenge of the project was to find a way of achieving a high antenna gain in the specified coverage region as well as sufficient mechanical properties.
Within the scope of a similar NASA project, an “optimized receive antenna and system for precision GPS-at-GEO navigation” has been developed and patented (US 7,489,271 B2). In contrast to it, the proposed SUGA solution offers the following benefits:
The proposed solution represents a one-arm helical antenna with truncated-cone reflector optimised for the L5/E5a-band. The helix is winded on a novel support cone-shaped structure, which exhibits a high mechanical stability and a low impact on the antenna gain. The cone is fixed on its base to a truncated-cone reflector with four feet. An integrated transmission line transformer makes sure an excellent impedance matching and is directly connected to the RF front-end on the bottom side of the reflector. The antenna is wrapped into a single-layer sunshield (Kapton-Germanium).
The project was started with a System Requirement Review (SRR) including system requirement definition (Task 1) and antenna requirement consolidation (Task 2).
The next milestone, Baseline Design Review (BDR), is covered by state of the art review and baseline selection (Task 3).
Detailed design and detailed link budget analysis (Task 4) led to a Design Review (DR).
After the EM antenna manufacturing (Task 5), a Test Readiness Review (TRR) was done.
The next execution phase is the Test Review Board (TRB), during which the results of antenna testing (Task 6) shall be reviewed.
The last milestone is Final Review (FR) including an analysis of test results (Task 7).