A transmission line structure includes a first transition element, a second transition element, and an active element. The first transition element has a radio frequency injection port and the second transition element, which is spaced from the first transition element, has a radio frequency termination port. An active element is in electrical communication with the first transition element and the second transition element. The active element includes a first and second connection region where the active element is attached to the first and second transition elements. The connection regions are configured to reduce reflection of electromagnetic energy.