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No. The J-Pole antenna is a 1/2 wave length long for the radiating section. The end of the antenna has a rather high impedance making for a very poor match to 50 ohm coax. Thus the extra length is due to an additional 1/4 wave matching section, the section with the short length of extra conductor parallel to the long one, where the tap point selected yields the desired 50 ohms. The overall length will be closer to 3/4 wave length long. At 462MHz the wave length is about 64.7 cm (25.8 inches) and 3/4's of that would be 19.1 inches, just what you measured.

 

http://www.ka3pmw.com/files/jpole_presentation_rev2.pdf

 

Actually my question was answered when it was revealed that the antenna I questioned was identified as a stacked dual band unit and not a UHF only antenna.

  • 3 months later...

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