Method and apparatus for increasing bandwidth of a stripline to slotline transition

摘要

An antenna element (10) has two dielectric layers (12, 13), which separate three ground planes (17, 18, 21, 22, 23). The three ground planes have respective slots (26, 27, 28), which collectively define a slotline communicating at an inner end with a balun hole (57) that extends through all of the ground planes and dielectric layers. Two capacitive switches (121) are supported within the balun hole, and each have terminals respectively coupled to the same ground plane on opposite sides of the balun hole. The capacitive switches are independently and selectively operated to dynamically vary the impedance characteristic of the overall balun structure that includes the balun hole and two switch assemblies, and which gives the antenna element good electrical performance over a wide bandwidth. The antenna element includes a stripline (36), and a stripline to a slotline transition exists at the end of the slotline adjacent the balun hole.