although locations on opposite lateral sides of the test area are also acceptable a test system for rebroadcasting am and fm signals and for broadcasting am and fm specialized i e dedicated test signals is shown in fig3 an am antenna 31 and an fm antenna 32 are located on the exterior of building 10 am antenna 31 is connected to a notch filter 33 and the filtered am broadcast signals are amplified in an amplifier 34 the amplified am signals are coupled to one input of a summing amplifier 35 an audio source 36 such as a compact disc player or a waveform generator generates other test signals which may be used in radio testing and are coupled to an am transmitter 37 which provides am broadcast signals to a second input of summing amplifier 35 audio source 36 may provide special tones for example for specialized vehicle testing the output of summing amplifier 35 is connected to a coaxial transmission line 38 which transmits the summed am broadcast signals to the antenna via a matching network 40 matching network 40 is optional and would be used only if needed to provide sufficient energy coupling to the antenna for the am antenna a first conductor.