Multihole Couplers for Overmoded Waveguide Systems

摘要

Directional couplers for transverse electric (TE) modes which selectively pick one mode from a mode mixture in an overmoded circular waveguide system are described. Unwanted modes are statistically nulled out in the coupling waveguide. Mode selectivity and directivity oscillate up and down with an increasing number of holes and finally reach 20 dB. A directional coupler for the TE02 mode (28 GHz, 63.4 mm circular waveguide) with 41 holes and a length of 1.6 m shows a directivity of 68 dB and suppresses TE01 with 58 dB, TE03 with 28 dB, TE04 with 34 dB, TE22 with 37 dB, and further modes TElm (l5, m6) with 17 to 34 dB.