Waveguide Modes of Operation

1-23 Q-23. What term is used to identify the forward progress velocity of wavefronts in a waveguide? Waveguide Modes of Operation The waveguide analyzed in the previous paragraphs yields an electric field configuration known as the half-sine electric distribution. This configuration, called a MODE OF OPERATION, is shown in figure 1-29. Recall that the strength of the field is indicated by the spacing of the lines; that is, the closer the lines, the stronger the field. The regions of maximum voltage in this field move continuously down the waveguide in a sine-wave pattern. To meet boundary conditions, the field must always be zero at the "b" walls. The half-sine field is only one of many field configurations, or modes, that can exist in a rectangular waveguide. A full-sine field can also exist in a rectangular waveguide because, as shown in figure 1-30, the field is zero at the "b" walls. Similarly, a 1 1/2 sine-wave field can exist in a rectangular waveguide because this field also meets the boundary conditions. As shown in figure 1-31, the field is perpendicular to any conducting surface it touches and is zero along the "b" walls. Figure 1-29.—Half-sine E field distribution. Figure 1-30.—Full-sine E field distribution.