Adjustable beam tilt antenna

An antenna assembly for producing a radiation pattern and capable of varying the beam angle of said radiation pattern comprising:

• a plurality of substantially annular radiating members arranged end-to-end in a stacked array with one end of said array being a signal feed end;
• signal feed means connectable to a signal feed line for coupling a signal between the feed line and said stacked array, said feed means including:
• a co-axial feed structure having inner and outer conductive feed elements and extending through said annular radiating members of said stacked array from said signal feed end of said stacked array towards the other end thereof;
• said inner conductive feed element having an end terminating at an adjustable feed point located between the opposite ends of said stacked array, and said outer conductive feed element extending substantially the entire length of said stacked array;
• first means for nonconductively electrically coupling the end of said inner conductive feed element to an adjacent one of said radiating members at said feed point adjacent to the end of said inner conductive feed element;
• and
• additional means for nonconductively electrically coupling said outer conductive feed element to adjacent one of said radiating members of said stacked array at additional adjustable points adjacent the opposite ends thereof;
• and
• means for adjustably supporting said stacked array and said co-axial feed structure and permitting relative axial movement therebetween and the adjustment of the position of said adjustable feed point along said stacked array to thereby alter the beam angle of the radiation pattern.