Impact of mismatch loss on mobile phone simulation for automotive testing

Automotive electronic systems must operate as designed while exposed to the RF energy produced by mobile transmitters including cellular telephones. Automotive OEMs often verify functional performance using test procedures delineated in ISO 11452-3 [1] and ISO 11452-9 [2]. Test procedures simulate the mobile device via use of a small antenna placed in close proximity to the electronic device. RF immunity levels are based on a specified net power delivered from a broadband amplifier attached to the antenna via coaxial cable. The ISO standard makes only cursory reference to minimizing the antenna VSWR and cable loss for accurate delivery of the specified net power. This paper will focus on the effect of mismatch loss and its specific impact on the error in the actual net power delivered to the antenna.