An antenna is known as "directional" if its pattern strongly favors a certain direction. A directional works by concentrating the signal in one direction at the expense of other directions. Also known as the "Beam" antenna.

Read the section on Yagi antennas if you are not familiar with directional ("beam") antennas and how they work. Also, you must read the section on Cubical Quads because hybrids are simply a combination of the two.

Hybrids

Yagi's and Quads are the two main types of beam antennas. There is one other known as the "Log Periodic". It is used mainly for TV antennas because its bandwidth is really wide. It its not a really high gain antenna. The next important category of beams is the hybrid. This simple means combining parts of the Yagi and Quad on the same antenna (some people call them Quagis (QUAd-yAGIS). Lets jump right to a figure so we can see what I mean, check out figure 1. This should look familiar to most CBers, it is the holy Moonraker 4. The Moonraker 4 uses a quad element for the reflector element. They could have actually made the directors quad elements too. I suspect they chose the quad element for the reflector because of the advantages I listed above about the quad parasitic elements (that they respond to all polarization's, so it should better block all signal polarization's that come in from the rear of the antenna, as opposed to just blocking horizontal and vertical). There is no magic to combining the quad and yagi on one boom that makes this antenna have higher gain than just a plain yagi or quad. The gain of the antenna depends on whether the driven element is a dipole or quad loop, where if its a quad loop, it will have 2db more gain than the dipole driven antenna.

Figure 1 - The Moonraker 4 (and Shooting Star) is a hybrid consisting of yagi (dipole) driven and director elements with a quad type reflector element. Benefits are discussed in the text.

Looking at figure 1, we can classify each element like this. The reflector element is a Quad loop. The driven elements are Yagi type (crossed dipoles), as are the two directors elements. You could actually make any combination of element types that you wanted.

I was kicking around the idea where to put this note for Moonraker users. One of the main things I wanted to accomplish with this web page was dispel common misconception. One of the biggest I see involves the Moonraker 4. Most operators think they can hop up their (hot-rod if you will) antennas like you can a Chevy Camaro (an American muscle car). Take my advice, you can not hop up a Moonraker (or most antennas) by by adding stuff on it (except for adding more director elements on beams). Most people come up with ideas to make money! The absolute worst mistake you can make on your Moonraker is adding the "rejection" kit that Copper Electronics' (and others) sell. Figure 2 shows the Moonraker 4 with the "rejection" wire in place.

Figure 2 - "Rejection" Kit. This kit adds extra wires to the reflector element. Read text for explanation why this is VERY BAD.