We are doing research on standard electric field (E-field) generation using waveguides. An electrical device should not be influenced by unexpected electromagnetic fields. Ordinary electromagnetic interference tests require uniform E-field illumination to the device under test. The E-field strength applied to the device should be sufficiently reliable for safety and a field probe employed for the measurements should be properly calibrated against the standard E-field strength. Although the standard field generation in an anechoic chamber has an advantage in the frequency band, that in a transverse electromagnetic (TEM) waveguide is still more useful in terms of compactness. In addition to this, generating a strong field in the TEM waveguide requires an amplifier with significant lower gain compared with that in an anechoic chamber.