A parallel-plate guide is partially filled with two lossless dielectrics (Figure 13.25) where ' r1 = 4.0, ' r2 = 2.1, and d = 1

A parallel-plate guide is partially filled with two lossless dielectrics (Figure 13.25) where ˆˆ'_r1= 4.0, ˆˆ'_r2= 2.1, and d = 1 cm. At a certain frequency, it is found that the TM₁mode propagates through the guide without suffering any reflective loss at the dielectric interface.

(a) Find this frequency.

(b) Is the guide operating at a single TM mode at the frequency found in part (a)?

Incident wave