Metal Chassis Tolerant Conformal High Impedance Surface Based LTE-2600 Automotive Antenna

Abstract

The number of antennas in cars is increasing by the day. The interaction of an automotive antenna with the car chassis presents a prominent design challenge. While patch antennas are resilient to the underlying chassis metal, they suffer from poor impedance matching bandwidth for a low-profile design. Dipole antennas provide higher bandwidths, but the radiation performance degrades significantly if the dipole is mounted less than a quarter-wavelength apart from the car chassis metal. This paper shows through consistent simulation and measurement results the significant benefits of using a dipole over a high impedance surface (HIS) when low-profile antenna designs for confined mounting locations close to the chassis metal are required. It was observed that the HIS-dipole delivered 35% total efficiency for a mounting location that was only 3 mm apart from the chassis metal. At the same time, a well-defined resonance with a sufficient bandwidth and a positive peak realized gain (2.6 dBi) for the LTE-2600 frequency band (2500…2700 MHz) were obtained. These results indicate a stable and reliable performance of plastic embedded HIS-dipoles in a car, and open new avenues for novel close-to-chassis automotive antenna integration locations.