Although the use of current state-of-the-art reflector antenna software allows designing very complex antenna systems, there is a lack of reliable and efficient design software that can include tracking modes in the feed horn mode spectrum. The objective of this project was to fill this market gap.
More specifically, the objective of this activity was the development of a software tool for optimising the RF performance of multi-mode horns with body-of-revolution symmetry for combined communication and tracking applications. The software must therefore be able to simultaneously optimise the communication and tracking performances of the horn.
The intention is to have the analysis tool embedded in the horn synthesis program. An optimisation routine will then optimise the initial geometry of the horn leading to a high performance feed. Another objective was to ensure that the optimisation process includes some critical mechanical constraints in order to obtain a mechanically feasible and cost effective design.
Once the software was developed, a breadboard horn for simultaneous telecom and tracking application at Ka-band had to be designed and tested to validate the accuracy of the software.
The key challenge of such a complex optimization process was to develop the most time-efficient algorithm without compromising the accuracy of the numerical solution. The efficiency of the design process was addressed by:
- Maximizing the accuracy of the initial design (starting geometry)
- Optimizing the numerical speed of the full wave analysis
- Use of highly efficient optimization routine(s)
Other challenges of the project included designing test capabilities and methods that are necessary for a proper validation of the software. TM01 and TE21 mode couplers which are necessary to test the tracking patterns had to be included in the test setup and properly calibrated. Mode couplers had to be de-embedded for VSWR measurements.
The key application of the developed design software is in Multiple Beam Antenna (MBA) Systems and any other antennas requiring tracking. Such high gain, narrow beam antennas degrade their performance quickly if their pointing errors are not compensated by closed-loop tracking systems. By optimizing the telecom and tracking mode performances simultaneously, the design tool is able to achieve higher performance compared to conventional software.
It should be pointed out also that even though the key application is in antenna tracking systems, the software general capabilities are much broader, allowing designing horn antennas for the most stringent requirements.
This software is a design tool that can perform the synthesis and optimization of horns for combined tracking and telecommunication applications. The design tool can simultaneously optimize the tracking and telecommunication performances of horns to yield high performance designs. The software can also perform an initial synthesis prior to optimization for certain horn types, based on user-specified RF performance requirements.
The software can handle a wide variety of horn geometries, including smooth wall and corrugated horns, and is limited to homogeneous structures exhibiting Body of Revolution (BOR) symmetry. The following geometries can be designed with the software:
Smooth Wall Horns:
- Conical horns
- Potter horns
- Modified Potter horns
- Profiled smooth wall horns
- Corrugated horns with corrugations perpendicular to the horn axis
- Ring loaded corrugated horns
- Corrugated horn with axial corrugations
- Coaxial waveguide corrugated horn
Hybrid Geometry Horns:
- An arbitrary combination of the smooth wall and corrugated horn geometries
The software is equipped with a pre-processor embedded within the software GUI (Graphical Used Interface). The pre-processor allows the user to set up an initial horn geometry based on performance requirements and design constraints (such as maximum overall length and manufacturing capabilities), as well as to define the electromagnetic modelling parameters. A comprehensive post-processor in both graphical and text formats has been developed to generate the output data.
The numerical engine is based on Combined Mode Matching, Boundary Contour Mode Matching and Spherical Wave Expansion methods that are widely recognized as the most time-efficient electromagnetic analysis tools, which ensures high accuracy and superior numerical efficiency. The optimization efficiency has been addressed by a flexible use of fast-convergent optimization tools such as Extreme or Powell methods.
The accuracy of the software was successfully validated by designing and testing a breadboard horn.
The software is able to operate on PC computers and work stations using MS Windows XP and its successors, such as Windows VISTA.
Task 1: Synthesis tool requirement definition
Task 2: Synthesis tool methodology and validation definition.
Task 3: Synthesis tool implementation requirements.
Task 4: Synthesis tool development
Task 5: Design of the multi-mode horn
Task 6: Prototyping and RF Testing of the designed horn
Task 7: Validation of the software
The project started on January 5th, 2007. All Tasks have been completed and the software was successfully validated through Breadboarding of a Smooth Wall Horn. A preliminary version of the software was delivered to ESTEC on May 1st. The final software version is scheduled to be delivered by June 12th 2009.