In RF circuits, what is a ‘T’ switching configuration?

A ‘T’ switching configuration is a way to improve isolation in RF circuits.  It comprises three reed relays.  The relays are arranged in the following manner: one is on the left upper part of a T, the second one in on right side of the T after the junction, and the third relay is mounted on the vertical component of the T.  For maximum isolation, the first and second relays are in the open state. The third relay is closed and its bottom end of the T is grounded.  With the first relay open any signal that leaks thru to the junction of the three relays will be shunted to ground.  Any signal still left at the junction will be further isolated by the open contacts of the second relay.  When conducting a signal through the ‘T’, both the first and second relay are closed allowing the signal path.  The third relay is open.  The ‘T’ configuration will improve isolation, but there will be some signal loss due to the longer signal path.