. Airborne radar. Airplanes; Guided missiles. 10-15] MISCELLANEOUS MICROWAVE COMPONENTS 547 twists are feasible in surprisingly short lengths. A typical 3-face, 90° step twist for X-band is only 1 inch long, yet has a very low VSWR over a 12 per cent band. The step-twist principle has been applied to an interesting variable twist useful as an oscillating rotary joint having both ports on the axis of rotation. The commercial unit shown in Fig. 10-19 will rotate ±90°, with a VSWR of under over the full 40 per cent waveguide Fig. 10-19 Step-Twist Rotary Joint Permits ±90° Rotation of
. Airborne radar. Airplanes; Guided missiles. 10-15] MISCELLANEOUS MICROWAVE COMPONENTS 547 twists are feasible in surprisingly short lengths. A typical 3-face, 90° step twist for X-band is only 1 inch long, yet has a very low VSWR over a 12 per cent band. The step-twist principle has been applied to an interesting variable twist useful as an oscillating rotary joint having both ports on the axis of rotation. The commercial unit shown in Fig. 10-19 will rotate ±90°, with a VSWR of under over the full 40 per cent waveguide Fig. 10-19 Step-Twist Rotary Joint Permits ±90° Rotation of a Waveguide About Its Own Axis. (Courtesy of Lieco Incorporated) The more conventional waveguide rotary joints, capable of continuous rotation, involve a mode conversion from rectangular waveguide to an axially symmetrical mode and back to rectangular waveguide again. Modes commonly used are the TEM coaxial mode, the TMoi circular magnetic mode, and the TEoi circular electric mode (Fig. 10-1 la, f, g). Such rotary joints commonly have both rectangular waveguide ports extending radially, or one radially and the other axially. Although rotary joints vary consider- ably in bandwidth and performance, units having a VSWR under over a 12 per cent band are now common. Disturbing resonances, occasionally found to occur in rotary joints, are best detected with a swept-frequency reflectometer while slowly rotating the joint through its full range. Spot frequency checks of VSWR seldom reveal such Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Povejsil, Donald J. Princeton, N. J. , Van Nostrand
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Keywords: ., bookcentury1900, bookcollectionbiodiversit, booksubjectairplanes
