By: KA5WNX
The Quad Beam Antenna
A Popular DXing Antenna
A Quad Beam antenna is generally composed of a series of square-loop elements arranged to provide a relatively high powered directional aerial.
The Quad Beam, much like theYagi Beam, in that the Quad-Beam antenna is made up of a Refelector element, a Driven element, and a series of parasitic elements.
The reflector preforms two jobs. First it launches the signal in a forward direction, and reflects signals coming in from the back side of the beam.
The driven element is a simple Quad loop or dual-loop for lower SWR's, and has a set of parasitic elements acting simular to a series of tuning forks in that the first one resonates the signal to the next one and so forth.
With each passing parasitic element the signal increases it's resonance. Each time you double the number of parasitic elements, you double the signal strength.
The Quad Beam, much like theYagi Beam, in that the Quad-Beam antenna is made up of a Refelector element, a Driven element, and a series of parasitic elements.
The reflector preforms two jobs. First it launches the signal in a forward direction, and reflects signals coming in from the back side of the beam.
The driven element is a simple Quad loop or dual-loop for lower SWR's, and has a set of parasitic elements acting simular to a series of tuning forks in that the first one resonates the signal to the next one and so forth.
With each passing parasitic element the signal increases it's resonance. Each time you double the number of parasitic elements, you double the signal strength.
The driven element is a full one wavelength loop, while the reflector is 5% percent longer and each parasitic director is -5% shorter in length.
For a single band wire length would be expressed as:
984/frequency in MHz = feet and inches.
A multi-frequency loop is expressed as:
1000/frequency in MHz = feet and inches.
For a single band wire length would be expressed as:
984/frequency in MHz = feet and inches.
A multi-frequency loop is expressed as:
1000/frequency in MHz = feet and inches.
Dimensions of a quad beam are slightly different to that of a Yagi antenna.
The Reflector is calculated at: 1030 /frequency in MHz .
The Parasitic director elements are calculated at: 935/frequency in MHz .
The spacing is calculated at: 123/frequency in MHz .
There is an exception... from the driven element to the first director is: 98.4/frequency in MHz .
All other spacings are at 123/f.
The Reflector is calculated at: 1030 /frequency in MHz .
The Parasitic director elements are calculated at: 935/frequency in MHz .
The spacing is calculated at: 123/frequency in MHz .
There is an exception... from the driven element to the first director is: 98.4/frequency in MHz .
All other spacings are at 123/f.
