= NOW 20 WPM = TEXT IS FROM JANUARY 2020 QST PAGE 58 = TUBE AND STAPLING THE EDGES TOGETHER AT THE ENDS. EXCITATION IS THROUGH A COAXIAL PROBE ROUGHLY A QUARTER WAVELENGTH FROM ONE END THE DIMENSIONS ARE NOT CRITICAL. THIS ONE SHOULD HAVE A CUTOFF FREQUENCY AROUND 3R2 GHZ. THE GUIDE LENGTH AT 3R456 GHZ, CLOSE TO CUTOFF, SHOULD BE VERY LONG, AND THE TWO MINIMA ARE FARTHER APART THAN THE LENGTH OF THE GUIDE. THE OPEN END OF A WAVEGUIDE RADIATES AS A LOW GAIN ANTENNA. PROBING THE STANDING WAVE PATTERN ALONG THE SLOT WITH THE END LEFT OPEN SHOWED A VOLTAGE STANDING WAVE RATIO VSWR LESS THAN 2, SO MOST OF THE POWER IS RADIATED OUT THE END. PROBING OUTSIDE THE OPEN END, USING THE PROBE AS A SHORT MONOPOLE, SHOWED A BROAD RADIATION PATTERN. HOWEVER, ROTATING THE PROBE 90 DEGREES DETECTED NO ENERGY THE WAVEGUIDE IS POLARIZED PERPENDICULAR TO THE BROAD WALL, AS = END OF 20 WPM TEXT = QST DE W1AW <