Delta Loop Calculator

How the triangular loop affects the result

A delta loop is a full-wave wire antenna arranged as a triangle, and the photograph above reflects the physical form that the calculator is intended to help size. The important feature is not simply the total wire length; the shape, feedpoint position, height and surrounding objects all influence the resulting impedance and radiation pattern. A delta loop can be installed with a high apex, a horizontal top section or another practical orientation depending on the available supports.

The calculator starts with the wavelength relationship for a loop and then applies the selected practical correction. That gives you a useful construction dimension, but it should not be treated as a final measured value. Wire diameter, insulation, corner geometry and the distance to ground all change the electrical length. If the loop is close to other conductors, the coupling can be significant enough that trimming based on a free-space calculation alone will be misleading.

Feedpoint placement is another important design choice. A bottom-corner feed can be convenient mechanically and can produce a different impedance from a side or apex feed. The feedline should leave the antenna in a way that does not unintentionally become part of the radiator. A common-mode choke may be useful depending on the configuration. After erection, measure the antenna at low power in the actual operating position. Trim conservatively, because adding wire back is harder than removing it. Use the calculated perimeter as your starting point, then let measured resonance, impedance and the intended installation geometry determine the final dimensions.