The circulator also includes a magnet on {HEAD ~ top} of the substrate over a resonator circuit part of the microstrip lines and a pole piece on the bottom of {TAIL ~ the substrate} beneath the ground for providing a magnetic field in the substrate between the microstrip lines and the ground such that signals are coupled between the microstrip lines in a particular direction 
The circulator also includes a magnet on { HEAD ~ top } of the substrate over a resonator circuit part of the microstrip lines and a pole piece on the bottom of { TAIL ~ the substrate } beneath the ground for providing a magnetic field in the substrate between the microstrip lines and the ground such that signals are coupled between the microstrip lines in a particular direction
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH