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I am using 2 array crossed yagi-uda antenna operating at 437.025 MHz. Where and how should I ground it? Should I ground at mast of antenna or to its metallic boom?

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A Yagi-Uda antenna is a dipole antenna (sometimes folded dipole) with extra parasitic elements. Both the dipole and the parasitic elements are symmetrical; therefore the antenna is balanced; therefore it does not require any connection to ground to perform as designed.

You may wish to use grounding for protection against lightning or electrostatic buildup, but those are independent of the antenna design and can be done away from the antenna itself. (Lightning protection is a complex topic and must consider the electrical connections and physical layout in the whole station and building.)

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  • $\begingroup$ Thanks for the answer. My antenna's SWR is changing on movement of cable. is this due to not grounding the antenna? $\endgroup$
    – shweta
    Jun 26, 2015 at 6:10
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    $\begingroup$ @shweta I think of two possible reasons: (1) You have a loose connection somewhere; make sure all connections are clamped tight. (2) You don't have a balun, which causes the feed line to act as part of the antenna and therefore affect the impedance. $\endgroup$
    – Kevin Reid AG6YO
    Jun 26, 2015 at 14:10
  • $\begingroup$ In the second case, adding a ground connection would likely make the SWR more stable, but it's just hiding the problem. $\endgroup$
    – Kevin Reid AG6YO
    Jun 26, 2015 at 14:14
  • $\begingroup$ Ok. Is it necessary to use balun in antenna? Or there is any other solution for stabilizing the impedance. $\endgroup$
    – shweta
    Jul 1, 2015 at 5:54

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