Quad antenna

A quad antenna is a type of radio antenna frequently used by amateur radio operators. Like a Yagi-Uda antenna ("Yagi"), a quad consists of a driven element and parasitic elements; however in a quad, each of these elements takes the form of a loop, which may be square, round, or some other shape.

History

The quad antenna is a development of several inventions.

In 1924, Moses Jacobson patented a loop antennas with rhombic shape.

In 1938, George Brown et al. patented a loop antenna with rhombic shape and quarterwave sides.

In 1951 Clarence C. Moore, W9LZX, a Christian Missionary and engineer at HCJB (a shortwave missionary radio station high in the Andean Mountains) developed and patented a two-turn loop antenna that he called a "quad". He developed this antenna to resolve issues caused by large coronal discharges while using a beam antenna in the thin air of higher altitudes. This is not the antenna termed "quad" today. Moore describes his antenna as "a pulled-open folded dipole" and describes the time when it was developed:

Quad (play)

Quad is a television play by Samuel Beckett, written and first produced and broadcast in 1981. It first appeared in print in 1984 (Faber and Faber) where the work is described as "[a] piece for four players, light and percussion" and has also been called a "ballet for four people."

It consists of four actors dressed in robes, hunched and silently walking around and diagonally across a square stage in fixed patterns, alternately entering and exiting. Each actor wears a distinct colored robe (white, red, blue, yellow), and is accompanied by a distinct percussion instrument (leitmotif). The actors walk in sync (except when entering or exiting), always on one of four rotationally symmetric paths (e.g., when one actor is at a corner, so are all others; when one actor crosses the stage, all do so together, etc.), and never touch – when walking around the stage, they move in the same direction, while when crossing the stage diagonally, where they would touch in the middle, they avoid the center area (walking around it, always clockwise or always anti-clockwise, depending on the production). In the original production, the play was first performed once, and then, after a pause, an abbreviated version is performed a second time, this time in black and white and without musical accompaniment. These are distinguished as Quad I and Quad II, though Quad II does not appear in print.

Quad (music)

Quad or QUAD was the name of a solo music project by Gary Ramon.

During his six-year hiatus from Sun Dial, Ramon embarked on an ambitious solo project, Quad, which combined ambient electronica with kraut rock. The result was a pair of self-titled albums. The first of these was released on Ramon's own Acme Records in 1997 as a 1000-copy limited edition on 12" clear vinyl with a transparent sleeve. The second Quad album was released in 1998 on the Prescription label as a 99-copy limited edition LP.

A 1999 American re-release of the first album on CD and 10" LP on the Man's Ruin label was scheduled, but eventually cancelled.

Both albums are now highly sought-after collectors' items.

See also

External links

Quad (rocket)

In rocketry, the Armadillo Aerospace Quad vehicle called Pixel is a computer controlled VTVL rocket that was used in 2006 to compete in the Lunar Lander Challenge.

General description

The quad vehicle design is a pressure fed in blow-down mode from an initial pressure of 320 psi for level 1 (400 psi level 2). The cold gas vernier engines are cross-fed by gas drawn from ullage space of the opposite tank. The vehicle was able to transfer propellant through connecting pipes between opposite tanks by controlling ullage pressures with the thrusters; this helps it balance, minimizing gas use. The main engine had two-axis thrust vectoring. The vehicle was fully computer controlled; with guidance from GPS and fiber optic gyros.

Specification

The specification for Pixel/Texel for level 1: