Delta-Loop Antenna

The delta-loop antenna is an alternative to a dipole antenna. It is similar to a folded dipole. In many cases it is less noisy in reception and it is more broad band than a plain dipole. The radiation and gain is similar to a dipole, gain being 0.65 dB higher. However, the effective height over ground of a delta-loop is less than that of a dipole at the same height of the top part of the loop. This means a much higher beam angle. This in case of the typical installation where the top part is suspended between masts and the feedpoint is hanging at the bottom. The feedpoint can also be elevated making a horizontal loop. By changing the feedpoint up one side or rotating the whole loop, in a vertical loop antenna a vertically polarized antenna can be made. The shape of the loop can be changed from maximal area with Ltop being L/3 to minimal area (folded dipole) with Ltop=L/2. L is always one full wavelength. The impedance of a delta-loop varies approximately from 100 to 300 ohms. The impedance increases as the area of the loop decreases. A large area delta-loop is often matched to 50 ohms using a quarter-wave 75 ohm coax at the feedpoint. See also my quarterwave impedance matching calculator.