Very efficient 5G/6G antenna array system (AAS) feed

A radio frequency (RF) feedline structure comprising:

• a first printed circuit board (PCB) including an upper metal layer, a lower metal layer, and at least one elongated cutout defining an upper portion of an open channel, the upper and lower metal layers being electrically connected by at least one of metal plating and a plurality of half-vias disposed along opposite walls of the at least one elongated cutout;
• a second PCB including an upper metal layer, a lower metal layer, and a plurality of elongated slots defining a suspended signal path disposed co-linearly within the open channel, the upper and lower metal layers being electrically connected by at least one of metal plating and a plurality of half-vias disposed along the suspended signal path;
• and
• a third PCB including an upper metal layer, a lower metal layer, and at least one elongated cutout defining a lower portion of the open channel, the upper and lower metal layers being electrically connected by at least one of metal plating and a plurality of half-vias disposed along opposite walls of the at least one elongated cutout;
• and
• respective upper and lower ground planes electrically connected to the upper metal layer of the first PCB and the lower metal layer of the third PCB, the upper and lower ground planes electrically closing the corresponding upper and lower portions of the open channel.