Can ETC be installed without sticking it to the windshield?

[AthenaFitz]

ETC does not have to be stuck to the windshield. Installing ETC on the upper part of the windshield is to minimize obstruction of the driver's view and to ensure better recognition by highway toll station equipment. As long as the highway toll station's sensing device can detect the ETC device, it can be installed on the car's dashboard or held up by hand when passing through the toll station. This will not affect the transmission of electromagnetic waves in free space. Electromagnetic waves will still refract and reflect when passing through different media, eventually reaching the signal receiver. ETC is an electronic toll collection system, and vehicles that frequently use highways usually install this device to save time when passing through toll stations.