A signal feed apparatus for an antenna including a slot through a conductive wall, comprises a non-conductive slot insert, a non-conductive block fixed to the slot insert and including first and second cable conduits and first and second plug sockets coinciding with first and second signal feed-points of the antenna. A signal cable is inserted into the cable conduits and includes first and second conductors. Conductive plugs are inserted into the first and second plug sockets to electrically connect the conductors to the first and second signal feed-points.