TM0n0 - and TMm10 - Mode Oversized Cylindrical Cavity Power Combiners

TM_m10 -mode power combining is treated in addition to conventional TM_0n0-mode combining in a multiple-device oversized cylindrical cavity having a window output structure. Mode analysis gives the condition for stable power-combining operation in the desired mode. By experiments both on TM_0n0 -mode combining (n = 2, 3, and 4) and on TM_m10 -mode combining (m = 2 and 8), it is shown that almost perfect power combining in the TM₂₁₀ mode can be achieved as in the TM₀₂₀ mode and that the power combining efficiency decreases gradually with increasing n or m. A possible advantage of TM_m10 -mode combining in an oversized cavity is suggested based on the experimental result that power combining in the TM₈₁₀ mode gives higher efficiency than in the TM₀₄₀ mode.