Topband: electrical wavelength

[Jim Hoge]

Let's do some quick math.... 234/1.82=128.57 gives us the length in feet of a quarter wave at 1.820 mHz. Multiply that by a velocity factor ( say 85% for LMR-400) and you get a length of 109.29 feet. The math will tell you that for every percentage point of velocity factor, it equates to 1.28 feet or 15 and 7/16 inches. Every degree of phase will then be 1/90 of the quarter wave length times the velocity factor. In this case, using 1.820 Mhz and a velocity factor of 85 then the equation is ((234/1.82)*0.85)/90=1.214 feet or 14 and 9/16". If you are reasonably careful in your measurements, your phase length will be fine. It comes down to accuracy of published velocity factor but I don't think it will present much of a problem. Move up to gHz frequencies and it's another story.

73,
Jim W5QM




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