2Current Progress Antenna Design Antenna Feeding Network Current antenna is 36 inches tall10 dB gain across 500 MHz to 2 GHz bandwidthImpedance between Ω, but should be uniform across frequency bandwidth.Antenna Feeding NetworkCurrent design offers good performance across the frequency bandwidth.Short board allows for cheap fabrication.Impedance transforming transmission line (50Ω to 170Ω) Fabrication and testing to be completed.Deploying MechanismSome possible design have been presented .No current final design has been determined.Antenna StructureABS material for use of RadomeDeformation should have little affect on gain pattern.Large amount of stress at conical base may need additional consideration when mounting to deployment base.
3Current Antenna Design Objectives Move towards Prototyping Structure and Deployment DesignDetermine suitable material for antenna structure.Study Viable options for mechanical deploymentFly on airplane to as preliminary testDesign Antenna Feeding NetworkImpedance transforming transmission line50 Ω to 170 Ω tapered lineBalanced line output to feed antennaFabrication and Testing of AntennaFabrication of feed networkAntenna gain pattern measurementsFeeding NetworkConical Spiral Antenna
4Antenna Feeding Network Microstrip tapered line to balanced parallel stripShorter PCB will allow for cheap in-house fabricationProvides good S11 and S21 across the frequency band1.93”193mil40mil10”3.3”Port 1170ΩPort 250ΩTop ViewBottom View0.2”Rogers, RT/Duroid 5880εr = h = .062 intanδ =t = 17μm
5Air Pressure Stress Analysis Yield stress of ABS:10 MPa (very minimum possible value)Predicted stress due to air resistance will not cause the ABS to failMagnitude of pressure applied to front surface area: 4.6 kPaStress is distributed evenly across the faceDirection of air flowMPa4 mm thickConical RadomeDirection of air flow
6Air Pressure Displacement of Geometry These renderings of deformation are purposefully very exaggerated in order to show regions of slight indentation and protrusionThe maximum displacement is experienced at the tip of the coneDisplacement will likely not have an effect on the Antenna gain PatternDirection of air flowmmDirection of air flow
7Concepts for Antenna Deployment Considerations for Antenna deploymentPivoting MechanismDeployment follows air dragLow ProfileClose to fuselage surfaceTotal footprint approximately antenna diameter.Electronic Motor controlledDouble acting air-cylinderScissoring arm extensionCrank window openerWeather and Temperature resilientAir Cylinder ConceptAntennaAir CylinderDeployedPositionNon-DeployedTransitionDirection of air flowScissoring ArmCrank Window Hinge
8Future Work Antenna Design Deploying Structure Finalize the Design Determine method for antenna fabrication.Study affects of ABS Radome on antenna gain pattern.Simulate effects of connecting the feeding network to the antenna.Finalize and prototype antenna design.Measure Gain pattern and ImpedanceReconfigure feed network impedance accordinglyDeploying StructureObtain ABS radome structure.Finalize and build deploying mechanism.Determine placement on fuselage.Mount and test deployment on aircraftFinalize the DesignCombine Antenna and Mechanical designs