The microwave assembly may be {HEAD ~ a monopole microwave antenna assembly} but is preferably {TAIL ~ a dipole assembly} 
The microwave assembly may be { HEAD ~ a monopole microwave antenna assembly } but is preferably { TAIL ~ a dipole assembly }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL