Angle-Dependent Path Loss Measurements Impacted by Car Body Attenuation in 2.45 Ghz ISM Band

In the past few years more and more wireless applications (e.g. WLAN and Bluetooth) have migrated into the automotive domain. With the increasing number of devices, coexistence investigations in the 2.45 GHz ISM band are gaining importance to enable reliable communications with real time requirements like voice transmission and streaming applications. This paper presents initial results on angle dependent path loss measurements impacted by the influence of a car body on electro-magnetic wave propagation. To this effect, a measurement methodology was developed to gather the attenuation effects of the car according to different antenna positions and measurement angles. Various kinds of attenuation measurements were performed. Vehicle shell attenuation measurements were transformed into angular-dependent path loss metrics and related to vehicle-specific attenuation properties like window inserts, roof columns, trunk or engine hood. Focus of attention was drawn to free space attenuation and intra-vehicle attenuation measurements.