Waveguide or Coax for Five Megawatts

The maximum visual effective radiated power now permitted by the FCC for UHF TV is 5 000 000 watts. All manufacturers now have available 110-to 150-kilowatt transmitters with antennas having power gains of 35 to 60. Stations contemplating an increase to the maximum permitted power are faced with the difficult problem of selecting the type and size of transmission line to be used. The choice is between 6 1/8-inch, 8 3/16-inch, or 9 3/16-inch coax line or WR-1500 or WR-1150 waveguide. This paper discusses some of the cost and technical tradeoff considerations that must be evaluated in selecting the proper type and size of transmission line.