The circulator also includes a magnet on top of the substrate over a resonator circuit part of the microstrip lines and a pole piece on the bottom of 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 {HEAD ~ the microstrip lines} in {TAIL ~ a particular direction} 
The circulator also includes a magnet on top of the substrate over a resonator circuit part of the microstrip lines and a pole piece on the bottom of 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 { HEAD ~ the microstrip lines } in { TAIL ~ a particular direction }
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL