Antenna Design Progress Chi-Chih Chen Research Associate Professor Domenic Belgiovane Graduate Student The Ohio State University ElectroScience Laboratory Electrical and Computer Engineering Department 1330 Kinnear Road, Columbus, OH 43212 TEL: (614) 292-3403, FAX: (614) 292-7297, Chen.118@osu.edu

Current Progress Antenna Design Antenna Feeding Network Current antenna is 36 inches tall 10 dB gain across 500 MHz to 2 GHz bandwidth Impedance between 150-180 Ω, but should be uniform across frequency bandwidth. Antenna Feeding Network Current 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 Mechanism Some possible design have been presented . No current final design has been determined. Antenna Structure ABS material for use of Radome Deformation should have little affect on gain pattern. Large amount of stress at conical base may need additional consideration when mounting to deployment base.

Current Antenna Design Objectives Move towards Prototyping Structure and Deployment Design Determine suitable material for antenna structure. Study Viable options for mechanical deployment Fly on airplane to as preliminary test Design Antenna Feeding Network Impedance transforming transmission line 50 Ω to 170 Ω tapered line Balanced line output to feed antenna Fabrication and Testing of Antenna Fabrication of feed network Antenna gain pattern measurements Feeding Network Conical Spiral Antenna

Antenna Feeding Network Microstrip tapered line to balanced parallel strip Shorter PCB will allow for cheap in-house fabrication Provides good S11 and S21 across the frequency band 1.93” 193mil 40mil 10” 3.3” Port 1 170Ω Port 2 50Ω Top View Bottom View 0.2” Rogers, RT/Duroid 5880 εr = 2.20 h = .062 in tanδ = 0.0009 t = 17μm

Air 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 fail Magnitude of pressure applied to front surface area: 4.6 kPa Stress is distributed evenly across the face Direction of air flow MPa 4 mm thick Conical Radome Direction of air flow

Air Pressure Displacement of Geometry These renderings of deformation are purposefully very exaggerated in order to show regions of slight indentation and protrusion The maximum displacement is experienced at the tip of the cone Displacement will likely not have an effect on the Antenna gain Pattern Direction of air flow mm Direction of air flow

Concepts for Antenna Deployment Considerations for Antenna deployment Pivoting Mechanism Deployment follows air drag Low Profile Close to fuselage surface Total footprint approximately antenna diameter. Electronic Motor controlled Double acting air-cylinder Scissoring arm extension Crank window opener Weather and Temperature resilient Air Cylinder Concept Antenna Air Cylinder Deployed Position Non-Deployed Transition Direction of air flow Scissoring Arm Crank Window Hinge

Future 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 Impedance Reconfigure feed network impedance accordingly Deploying Structure Obtain ABS radome structure. Finalize and build deploying mechanism. Determine placement on fuselage. Mount and test deployment on aircraft Finalize the Design Combine Antenna and Mechanical designs