Frequency/Diameter/Length Scaling

Any antenna design can be scaled for use on another frequency or on another amateur band. To scale an antenna properly, ALL physical dimensions must be scaled, including element lengths, element spacings, boom length and element diameters. This usually results in a scaled element diameter of inconvenient size. Simply changing the diameter is not satisfactory without making a corresponding element length correction. This web page computes both Frequency scaling and Element diameter/length scaling.

This page contains two calculators. One for Frequency Scaling and another for Element Diameter/Length Scaling. Areas are provided for input data and output data is written in RED.

The calculator on the left, Frequency Scaling, is for scaling a antenna element that is cut for one frequency to another frequency. For example, say you had designed a antenna wire that resonated on 20 Meters at 14.200 MHz. The element was 33' 5-1/2" (10.196 meters) in length. But you want to scale the wire to the lower end of 20 Meters, 14.050 MHz. The calculator should show that lengthening the element to 33' 9-11/16" (10.305 meters) would work. This should get you very close to the length you need. Note that, since this is just a straight forward scaling operation, dimensions are not required. The output will be in the same dimension as the input.

The calculator on the right, Element Diameter/Length Scaling, is for scaling a antenna element that is cut for one frequency to another frequency, in diameter as well as length. Similar to the previous example, say you have a element design for 14.200 MHz that specifies 1" tubing for the driven element. The length is specified to be 33' 5-1/2" (10.196 meters). But, you only have 1-1/2" tubing available and you want to move the frequency to 14.050 MHz.

What should be the length of the available 1-1/2" tubing, at 14.050 MHz?

At the top of the Element Diameter/Length Scaling calculator, you would first enter the Original Frequency (14.200 MHz) and the Scale Frequency (14.050 MHz). That should generate a Scale Factor of 1.011:1. Then enter specified Element Diameter and Element Length of 1" and 10.196 meters, respectivly. The calculator should show that, the Scaled Diameter and Scaled Length is 1-1/64" (25.7 mm) and 34' 10-7/8" (10.64 m), respectivly. At the bottom of the calculator, adjusted for 1-1/2" tubing, is the Corrected Length of 33' 8-11/16" (10.279 m).

Input dimensions can be mixed and matched. Enter your data in the areas provided and then just click anywhere on the page. The calculator output will be updated automatically.