420 likes | 740 Views
Dual Frequency Patch Antenna Array. Timothy Horan & Emal Latifzai Group 34 ECE 445 04/27/2007. Introduction. Antenna uses L1 (1.575 GHz) currently in use for civilian GPS applications, and L5 (1.176 GHz), which will be used as a safety-of-life signal in the near future.
E N D
Dual Frequency Patch Antenna Array Timothy Horan & Emal Latifzai Group 34 ECE 445 04/27/2007
Introduction • Antenna uses L1 (1.575 GHz) currently in use for civilian GPS applications, and L5 (1.176 GHz), which will be used as a safety-of-life signal in the near future. • Compact profile allows the user the ability to use it in conjunction with vehicular GPS applications.
Introduction – Features • Microstrip patch edge fed on adjacent sides to produce circular polarization. • Quarter wave transformers used to step input impedance down to 50 ohms. • Hybrid network splits the phase of the incoming voltage so that the two feeds are 90 degrees out of phase.
Product Overview – Block Diagram Hybrid Network L1 Patch To Detection and Demodulation Hardware Power Combiner Hybrid Network L5 Patch
L1 Antenna - Overview • Initial Design was created using a program developed by Professor Bernhard’s group • Antenna simulations were performed in Ansoft Designer (student version).
Initial design allowed for epr and substrate thickness to be designated by user, although final design used board materials that the parts shop can manufacture Quarter wave transformer defined in ADS and imported modeled in Ansoft L1 Antenna Overview – cont’d
L1 Antenna - Simulations • Size of patch was optimized so that resonance occurred at 1.575 GHz. • From simulations we could gather information about S22 (return loss), radiation pattern, VSWR, gain, polarization, and input impedance (with and without qwt).
Hybrid Network • The Hybrid Network was designed in Advanced Design System (ADS), using the Line Calc tool. • Hybrid size is frequency dependent
L5 Antenna Overview • Balanis Antenna Formulas • Professor Bernhard’s “ustrip_patch_calc” program to design antenna
L5 Antenna • Ansoft Designer SV • 60.4mm x 60.4mm • Ansoft Designer SV • 60.57mm x 60.57mm
L5 Hybrid Network • Advanced Design System (ADS) LineCalc Program
Final Layouts – L1 • Wires are RG-174 with SMA connectors • Hybrid Port 4 has a surface mount 50 chip resistor
Functional Tests – L1 • Return Loss, phase of hybrid, SWR, resonance point, as well as match to 50 ohms at resonance. • Further tests were performed in the anechoic chamber to get the radiation pattern.
L5 Eagle Layouts • Antenna • Hybrid
L5 Antenna Prototype • RG-174 wires with SMA connectors • Hybrid 4th port termination
VNA Functional Tests – L5 1st Design • S11 SWR • S11LogMag • S11 Smith Chart
VNA Functional Tests – L5 2nd Design • S21LogMag • S11 SWR • S11 Smith Chart
VNA Functional Tests – L5 Hybrid • Phase 2nd Port • Phase 3rd Port • Phase Diff. =~ 91.08º
VNA Functional Tests – L5 • S21LogMag • S11 SWR • S11 Smith Chart
Anechoic Chamber Functional Tests – L5 • 80% BW =~ 120º • 90º Phase Diff. over 210º BW
Future Developments • Get the resonance point to L1 and L5 respectively. • Develop power combination/division network. • Use better coupling method that provides less loss • Consider stacked patch design • Single feed point – could also eliminate need for hybrid network.
Other Considerations • There are no possible ethics violations with which we should concern ourselves.
Credits • Mr. Ethan Miller • Prof. Bernhard • Mr. Tyrone Roach, Ms. Zhuohui Zhang • ECE Parts Shop (Mark, Wally and Frank)