Quad antenna

patent US2537191

The Quad antenna is an antenna which is frequently used by amateur radio operators. It consists of a driven element and parasitic elements, like a Yagi; however, the elements are square loops. If there is only one parasitic element it is referred to as a 'Cubical Quad' (since it will be an approximate cube).

A quad will typically have similar performance to a Yagi having one more element (so the common cubical quad performs similarly to the common 3 element Yagi). Quads have a smaller turning circle, making them useful if they need to be rotated in a tight space.

It was developed by Clarence C. Moore (patent no. 2,537,191), W9LZX, an engineer at HCJB (a shortwave missionary radio station high in the Andean Mountains). He developed it to resolve issues with large coronal discharges in the thin air with a beam antenna.

Moore describes his antenna as "a pulled-open folded dipole" and describes the time when it was developed:

We took about one hundred pounds of engineering reference books with us on our short vacation to Posoraja, Ecuador during the summer of 1942, determined that with the help of God we could solve our problem. There on the floor of our bamboo cottage we spread open all the reference books we had brought with us and worked for hours on basic antenna design. Our prayers must have been answered, for gradually as we worked the vision of a quad-shaped antenna gradually grew with the new concept of a loop antenna having no ends to the elements, and combining relatively high transmitting impedance and high gain.

Patents

• Patent 2,537,191

References

• All about Cubical Quad Antennas by William I. Orr