A quad antenna is a type of directional wire radio antenna used on the HF and VHF bands. A quad is a Yagi–Uda antenna ("Yagi") made from loop elements instead of dipoles: It consists of a driven element and one or more parasitic elements; however in a quad, each of the loop elements may be square, round, or some other shape. It is used by radio amateurs on the HF and VHF amateur bands.

History

The quad antenna is a development of several inventions.

Advantages over a dipole-based Yagi–Uda

Rigorous testing of the loop Yagi–Uda (quad) antenna show the following advantages over a dipole-based Yagi–Uda antenna made from dipoles:

Disadvantages compared to other antennas

<span class="anchor" id="E_Z_O_anchor">The E-Z-O variation

In 2008, Daniel Mills,, designed an antenna that may be an improvement over the quad design. His E-Z-O antenna uses flexible dielectric tubes rather than rigid poles to support the electrical elements. He claims slightly higher gain over the quad due to its roughly circular form. The claimed magnitude of the dielectric effect on the outside band elements was a surprise, and optimum element lengths were determined by experiment. No reference literature was found: state "As far as we are aware, there has been no reported work on encasing loop antennas in dielectric."

Sources