It is well known that a large plane reflector directly above and normal to the axis of a cylindrical transducer can have a rather drastic effect on the beam patterns of such a transducer. The degree of such an effect is, of course, dependent on size and material of the reflector, distance above the active face of the transducer, and the size of the active face of the transducer in wavelengths. Experimental data will be presented indicating some of the precautions one must take to guard against such effects or to use these effects to one's advantage if desired. Information will be presented, for both plane and conical reflectors, as to the beam depression, beam width, effective hydrophone sensitivity, and minor‐lobe structure as a function of reflector dimensions and for various distances of the reflectors above the active face. (This work is supported by the Bureau of Ships.)