An Analysis of Junction Discontinuity Ef- Fects in the Multi-element Coupled Lines and Its Diminution at Designing Stage

The analysis and design of the multi-element coupled lines, in conjunction with the junction discontinuity effect, is presented, and its applicability in high power rf regime is discussed. Junctions are usually employed to connect two different coupled elements, which gives rise to undesirable reactance, i.e., junction discontinuity effect. These effects are found prominent in the high power coupled lines for HF and VHF applications because of its large structural dimensions. The design and simulation of 3-element, 8.34 ± 0.2 dB coupled line section rated for 38 to 112 MHz and 200 kW has been performed. The simulated results are significantly deviated from the theoretically calculated ones where the discontinuity effect is usually ignored. A generalized theoretical procedure is developed to take into account the effect of junction discontinuity at the designing stage. The theory is applied to the 3-element 8.34 ± 0.2 dB coupled-line section, and simulation is performed by using standard Ansoft HFSS software. The HFSS simulation results are in close agreement with the theoretical predictions.