Antennas Hidden Inside the Vehicle Roof Gerald Artner Robert Langwieser Christoph Mecklenbräuker Jerzy Kowalewski (Karlsruhe Institute of Technology)

Current Automotive Antennas Shark-Fin Modules  Contain: • • • • •

GPS 2G, 3G, 4G (MIMO) Car-to-car (MIMO) Satellite Radio Remote Keyless Entry

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Antennas Hidden Inside the Roof

car clip art openclipart.org copyleft

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Chassis Antenna Cavity  Vehicle antennas in a cavity in the chassis  Preferred position in the roof  Large, contains many antennas

G. Artner, R. Langwieser and C. Mecklenbräuker, “Concealed CFRP Vehicle Chassis Antenna Cavity,“ in IEEE Antennas and Wireless Propagation Letters, doi: 10.1109/LAWP.2016.2637560

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Chassis Antenna Cavity  Prototype built  Carbon fiber reinforced polymer

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Standard Antennas

 3 antennas • monopole 5.9 GHz • IFA 2 GHz • conical monopole 1-10 GHz

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Standard Antennas – Return Loss  Good return Loss > 10 dB

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Gain Measurements  Anechoic chamber  Built a fixture

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Chassis Antenna Cavity

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Chassis Antenna Cavity  Broadband description from cone  Cavity corners visible in pattern

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Pattern Reconfigurable Antenna With Four Directions Hidden in the Vehicle Roof  2.6 GHz antenna can be reconfigured to radiate in 4 directions

G. Artner, J. Kowalewski, C.F. Mecklenbräuker and T. Zwick, "Pattern Reconfigurable Antenna With Four Directions Hidden in the Vehicle Roof," accepted iWAT 2017.

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Pattern Reconfigurable Antenna  Reconfigure towards front, back, left or right  PIN diodes  2.6 GHz LTE

J. Kowalewski, T. Mahler, C. Heine and T. Zwick, „Compact pattern reconfigurable LTE antenna,“ International Workshop on Antenna Technology (iWAT), Sydney, 2014, pp. 72-75.

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Chassis Antenna Cavity  Antenna fits  Enough space for more antennas

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Measurements  Calibrated gain measurements in anechoic chamber  „car roof“ 1x1 m² carbon-fiber reinforced sheet

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Return Loss  Return loss better than 15 dB  Resonances shifted only slightly  (without cavity 15 dB front and 25 dB right)

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Gain Pattern in Driving Direction  ~3 dB additional gain front/back  ~10 dB gain difference front/side

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Gain Pattern Towards the Side  ~5 dB additional gain left/right  ~10 dB gain difference side/front

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Conclusion Antennas can be built into the vehicle roof. Advanced antennas (like pattern reconfigurable antennas) also work there. We are moving towards a smart vehicle roof.

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S11 without cavity

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Vienna (TU Wien) – Karlsruhe (KIT) Short Term Scientific Mission

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