Compact spherical reference radiation source for the transfer of ‘Interference Field Strength’ value, offers very good price-performance relation. The KSQ 1000 is a special version of reference radiation source for the frequency range 30 MHz to 1 GHz. It consists of a battery operated comb generator which generates selectable frequency spectra with 1 MHz, 5 MHz or 10 MHz distance of the discrete spectral lines. The basic frequency 10 MHz is supplied by an ultra stable crystal oscillator. The complete circuit is mounted into two metallic half spheres, which provide a dipole antenna for the radiation of the generated frequency spectrum. This configuration supplies little dimensions of the KSQ 1000 and allows operation in small test areas (e.g. GTEM 250).