by using a single aperture of dimensions not greater than the shortest operating wavelength

Introduced: September 1968

Full Title

Full titles differ between systems:

IPC:

Details of transducers > Arrangements for obtaining desired frequency or directional characteristics > for obtaining desired directional characteristic only > by using a single transducer with sound reflecting, diffracting, directing or guiding means > by using a single aperture of dimensions not greater than the shortest operating wavelength

CPC:

Details of transducers, > Arrangements for obtaining desired frequency or directional characteristics (for stereophonic purpose H04R5/00) > for obtaining desired directional characteristic only > by using a single transducer with sound reflecting, diffracting, directing or guiding means > by using a single aperture of dimensions not greater than the shortest operating wavelength

No child classifications to compare. This is a leaf node in both IPC and CPC.