G9C19 (D)  
What configuration of the loops of a two-element quad antenna must be used for the antenna to operate as a beam antenna, assuming one of the elements is used as a reflector? 
A. The driven element must be fed with a balun transformer
B. The driven element must be open-circuited on the side opposite the feed point
C. The reflector element must be approximately 5% shorter than the driven element
D. The reflector element must be approximately 5% longer than the driven element
