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Published byDerick Perkins Modified over 9 years ago
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Fire Dispatch Drill RACES ANTENNA FUNCTIONAL PRIORITIES Must Communicate Securely Mounted Rapid deploy/removal Avoid O/H Obstructions Leave no marks ANTENNA CONCERNS
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Fire Dispatch Drill What Didn’t Work Well Roof-top or Window mounted 5/8 λ or 1/4 λ antennas using a suction cup mount with/without hookup wire radials Clip-On Window mount rubber duck antennas Rubber Duck Antennas inside the Station or the FD vehicles What Did Work Well 5/8 λ or 1/4 λ mag mount base antennas sitting in contact with the diamond plate roof top. 1/2 λ antennas mounted on any surface Suction Cup Mounts having pre- tuned brass rod radials ANTENNA CONCERNS
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- Aluminum Diamond Plate provides good match and gain - Magnetic base should be in direct contact with roof - Must be duct taped in place (not shown) -Good VSWR, 360 degree Coverage 1/4 λ Vertical Magnetic Mount Mobile Antenna Recommended - Low profile - Low Drag - Adequate Gain
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1/4 λ Suction Cup/Magnetic Mounted Antenna Second Best Option - Low profile - Low Drag - Adequate Gain - 3 Brass Rods provide adequate ground plane - Length of Radial Rods need to be VSWR tuned beforehand - Coax cable must not run close to, or parallel to, radial rods - Can mount to any flat surface, conductive or not
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1/2 λ Suction Cup/Magnetic Mounted Antenna 3 rd Option Totally flexible mounting while maintaining tune/match ie, can mount on conducting or non-conducting surfaces Radials and/or Gnd Plane are not necessary for match Must have internal L-Network to Match coaxial feedline 51” Tall, so has overhead obstruction issues Additional wind drag Gain, only if mounted on conducting surface or with Radials Eliminates Radial Rod complexity
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Fire Dispatch Drill ANTENNA RECOMMENDATIONS It’s recommended to have a 1/4 λ magnetic mount antenna. It can be taped (use non residue duct tape) to an aluminum diamond plate roof, or attached to a steel roof. The metal roof provides a match and gain. The roof is high and enables a symmetric 360 degree pattern. Short Antennas are best, but 1/2 λ antennas are easy to use if height is not a problem. Avoid, if possible, mounting to non-conducting surfaces that lower gain and will require radials to obtain a match If radials are necessary, use pre-tuned Brass Rod Radials and avoid using “hookup wire” radials
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