Sentence:  Very recently , observations have been made at 8 - mm wave length with a reflector 22 meters in diameter with a resultant beam <WSD>width</WSD> of only about 2 ' ( Amenitskii , Noskova , and Salomonovich , 1960 ) . 
Meaning of the word marked with <WSD> tags:  the extent of something from side to side