In cooperation with: Laboratorio Antenne e Microonde Automotive Glass Antenna for Worldwide Cellular Phone Coverage Author: M. Cerretelli, ASK Industries SpA & University of Florence (IT) Presenter: Simone Ledda, University of Florence
C-type antenna intended for automotive internal glass installation Worldwide mobile phone bands (LTE compatible) 3G: from 810MHz to 960MHz and from 1.71GHz to 2.17GHz Extensible to LTE (4G) worldwide (690MHz 960MHz and 1.71Ghz 3.13GHz) No need of any dedicated matching network developed under an R&D cooperation program between the ASK Industries Group and the Microwave and Antenna Laboratory (LAM) of the University of Florence (Italy) Page 2
Antenna layout Page 3
Side view of the proposed antenna: schematic dimensions bent metallic plate and two 1.6 mm thick PCBs (FR4) overall volume of 80x60x20 mm 3, placed 4mm apart from the internal glass surface Page 4
Simulation settings 4.2Mln cells with limited dummy roof Mesh aligned with antenna s PCB Glass: ε r =7, tanδ=0.02 Transient Solver; energy stop -40dB Simulation time: About 18minutes with dummy roof [HP xw8600, dual Intel Xeon X5470 12MB cache, 8 cores @ 3.3GHz] Page 5
Simulation settings 45Mln cells with real car Mesh aligned with car Transient solver; energy stop -30dB Simulation time: About 3days with car (16Gb ram) [HP xw8600, dual Intel Xeon X5470 12MB cache, 8 cores @ 3.3GHz] Page 6
Simulation vs measurements: input matching Page 7
37mm / 76mm Automotive Glass Antenna for Worldwide Cellular Phone Coverage Performance comparison with other antenna types C-antenna Floating Monopole Slot antenna Page 8
Floating monopoles matching Page 9
Simulated patterns on real car with different antenna type (same position) C-antenna monopole 960 MHz 1880 MHz Page 10
Simulated patterns on real car with different antenna type (same position) Horizontal Cut for Theta=90 - Red curve for C-antenna, green for Monopole 960 MHz 1880 MHz Page 11
Simulated LAG, Linear Average Gain obtained by linearly averaging the simulated realized gain on a 360 (step 1 ) azimuth rotation for an elevation of 0 above the horizon C-Antenna vs Monopoles (two, for the two bands of interest) 76mm monopole 37mm monopole Page 12
Open Area Test Site (OATS) for external vehicle measurements at ASK Turntable RF COAX 10m 40m Copper - 10m MOTION CONTROLLER HD 100 Optical fiber 60m PC RF COAX 60m NETWORK ANALYZER HP 8714ET TXRX CONTROL STATION 2.5x3m Page 13
LAG, Linear Average Gain, measured at ASK Open Area Test Site obtained by linearly averaging the measured gain on a 360 (step 1 ) azimuth rotation for an elevation angle of about 5. All measures are normailized to the radiation of a quarter wavelength monopole (dbq) placed in the center of the car roof. Three antenna type, same installation: C-Antenna, Slot antenna and monopole Radiation differences mainly related to mismatch (slot antenna not well matched over 1.95GHz) Page 14
Conclusions Standalone antenna performances are optimized to achieve a wideband input matching with the higher allowable radiation efficiency The limited ground plane simulation is representative of the input matching of the antenna installed onto the car and can be used for optimization Radiation performances strongly depend on the chosen installation position inside the car If the installation point inside the car is compelled by the car manufacturer, as frequently happens for design and/or cost reason, radiation performances cannot be much controlled by simply tuning the antenna, which essentially acts as a field source in a complex near field environment Author email: matteo.cerretelli@unifi.it Page 15