  So far, cosmic ray air showers have been detected using scintillation counter
arrays on the ground widely. And also air Cherenkov detection method, which is
limited its observation period in moonless nights, has been adopted. The
detection method of radio emission from cosmic ray air showers is not new, but
rather old method. Radio emission from cosmic ray air showers has not been
detected with the method of self-trigger system. If the detection method of
radio emission were available, there is no limit of the observation like
Cherenkov counter. The developments of high radio frequency (RF) technology
might make the detection of radio emission from extensive air showers possible.
Antennas calibrated in laboratory are available. With those antennas, we can
directly obtain the absolute intensity of radio frequency from cosmic ray air
showers. Main issue to detect radio emission is that signal level is quite low.
The thermal noise particularly causes background noise source. Those issues and
detection method are discussed. We also describe an antenna detection method to
generate self-trigger signal and a method to identify air shower events from
natural and artificial noises.
