Analysis of an open-ended waveguide radiator with dielectric plug

The paper presents a moment method analysis of an open-ended waveguide radiator when a dielectric plug is pushed into the radiating end. It is demonstrated that such a structure behaves as a very good radiator of microwave energy over a band of frequencies. Experiments were carried out with polystyrene plugs, of different thicknesses, inserted at the end of a WR-90 X-band waveguide, and excellent agreement between theory and experiment has been achieved. The analysis also shows that the frequency band of best match can be varied over the frequency range by adjusting the thickness of the plug which is inserted at the radiating end.