Antenna Design Progress Chi-Chih Chen Research Associate Professor Domenic Belgiovane

1. 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

2. Current Progress • Antenna Design • 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 (50Ωto 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.

3. 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

4. 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 10” Port 1 170Ω Port 2 50Ω 3.3” 193mil Top View 40mil 1.93” 0.2” Bottom View Rogers, RT/Duroid 5880 εr = 2.20 h = .062 in tanδ = 0.0009 t = 17μm

5. 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 MPa Direction of air flow 4 mm thick Conical Radome Direction of air flow

6. 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

7. Concepts for Antenna Deployment Antenna Deployed Position • 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 Air Cylinder Transition Direction of air flow Scissoring Arm Crank Window Hinge Non-Deployed Position

8. Future Work • Antenna 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