The ALX-4000 is an ultra-broadband antenna for emission measurements and immunity tests according to nearly all relevant international standards in the frequency range from 25 MHz up to 4 GHz. With regard to its mechanical structure it is a linear polarized logarithmic periodic broadband antenna for the higher frequency range, combined with a 4:1 broadband dipole (aluminum) for the low frequency range. This kind of ultra-broadband antenna allows performance of EMC test in one run, without time consuming antenna changes. The ALX-4000E is an especially optimized version for emission measurements. It offers lower antenna factors and improved VSWR. Additionally it can be used for immunity tests which require an input power of less than 100 W cw (200 W intermitt.). The ALX-8000E has an extended frequency range up to 8 GHz. All antennas are supplied with antenna factors for 3.0 m and 10.0 m measuring distance (1.0 m on request).