The G5RV-JR antenna is a unique all band antenna.  It consists of a 51 foot flat top
plus 17 feet of 450ohm ladder line.  In this instance, the ladder line is an active
part of the antenna and radiates RF.  Because of this, it must be fully extended
and can not contact the earth or run parallel to metallic objects.   Coax is attached
at the end of the ladder line.  Most modern radios with an internal antenna tuner
can accommodate this antenna and provide a good match on all bands from 40-10M.
This is an ideal antenna for limited space.