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From: Dick Boley
Date: 24 Jun 1999
Time: 07:34:55
Remote Name: 209.76.248.8
The following from GAP....
Here is a little more info on the Super C antenna.
Chris
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GAP ANTENNA PRODUCTS PRESENTS
A 21st Century Antenna
IT MAY BE SMALL, BUT IT IS LOUD
SUPER "C" PERFORMANCE
Overall Height = Only Three Feet!!!! Goes Almost Anywhere = Ground, Roof, Attic, Porch, R.V....... Three feet is full size = 1/4 wavelength not a requirement Very small footprint = 900% less than normal radial area Exceptional Efficiency = Efficiency approaches 100% Outstanding immunity = Virtually undisturbed by nearby metal Near Zero earth loss = Earth Loss is not a major factor Primarily a vertical = Omni Directional - Low angle coverage Multiband = 20m - 17m - 15m - 12m - 10m Broadband = Inherent bandwidth w/o loss TVI - EMI low = Not prone to coupling on wires
HOW AND WHY IT WORKS
For the past 80 or 90 years an antenna had to be 1/4 or 1/2 wave long to establish resonant operation. If a shortened version was required, an inductor was inserted to replace the "missing len h." Further, if an antenna's length has been significantly reduced, one must accept degraded performance i.e. less than 100% efficiency and in most instances much less than 100%. NOTHING HAS CHAN D IN 90 YEARS.
One can hear it now --- "Its been the sole solution for all these years, it must be the solution." If there was a real alternative, we would have seen it years ago." Well, GAP apologizes for bei late but there is another real solution. GAP has proved an antenna does not have to be 1/4 or 1/2 wave long to resonate. You can forget the huge coil. Not only does Super "C" confirm this, Supe "C", in addition, establishes a number of truly unique and advantageous qualities.
What is a Super "C"? It is a radical change to H.F. antenna design. It is the first fundamental change in over 50 years. The typical, tall, vertical aluminum mast is gone, and replaced with a s rt, large diameter, aluminum mesh cylinder. The cylinder has been "squared" forming a basket. The basket is placed above a very short thin conductive mast. The basket/mast assembly is, in turn, aced above a collector-grid of aluminum mesh. The radius of the collector-grid approximates the height of the basket/mast assembly. The collector-grid, for the moment, can be assumed to replace typical radial configuration. Its characteristics; however, are entirely different and it is dramatically smaller. A 20 meter Super "C" version is shown in the figure. It is three feet high!!!! The collector-grid is very small, six feet by six feet. To put this in perspective, radial system for a 20 meter vertical, would be 35 feet in diamete
The well known antenna family of wire/rods are magnetic field dominated or MDR. They have very little surface area and require a length such that electron current flow created by an RF source,
as a transmitter, will have sufficient length to continue to flow upward or outward on the wire until the RF source changes phase reversing the current flow. The longer the "on" cycle (the lower e frequency) the longer the wire must be.
The Super "C" design replaces this wire/rod with a large surface area mesh in the form of the basket. The basket is positioned above a flat aluminum mesh surface, the collector-grid. These two e ments combine to form a huge capacitor which in turn creates a large electric field. The large surface area provides space for the electrons to collect during each RF cycle. This antenna is a E f ld Dominated Radiator or E.D.R. From a resonance standpoint the capacitor dramatically reduces antenna capacitive reactance. It is reduced until its, reactance matches the small inductive react of the short mast. When matched, you have a resonant antenna.
Maxwell and Poynting, pioneers in electromagnetic radiation, in the late 1800's developed the basic equation EXH=S. The E field vector "crossing", or interacting with the magnetic field vecto H, produces EM radiation S. Both fields must be present. If one antenna has a large magnetic field 10H and a small electric field 2E, radiation is 10H X 2E = 20S. If instead, the antenna has a l ge electric field, 10E, and a small magnetic field, 2H, radiation is still 20S. The output is the same, but the antennas are very different. Somewhat like the tube and the transistor, both provid gain, but they sure are different.
To understand the major difference between these antenna types, MDR and EDR, we go back to high school physics. In high school, the instructor attached a loop of wire to a sensitive meter. The i tructor then pulled this wire across a horseshoe magnet. The meter deflected!! Electron current was caused to flow in the wire by the magnetic field - a galvanometer. No one yet knows exactly ho but it does. Now for an experiment that was not done. We are going to charge two close spaced (1") copper plates with 50 volts and then drag the same wire between the charged plates in its E fie . What happens??? NOTHING!!!! An electric field does not cause current to flow in a wire. This very basic characteristic makes the two antenna types, EDR-MDR, vastly differen Of the many unique Super "C" characteristics three are of great significance;
IMMUNITY EARTH LOSS EFFECIENCY
Immunity is an integral characteristic of an E field antenna because its magnetic field is small. The MDR Antenna is its own magnetic generator inducing current in anything conductive near it.
Super "C" or EDR, absent a large magnetic field, produced the following test results on 20m:
1) A 33' aluminum mast was placed within one foot of the Super "C" collector-grid. Super "C" VSWR of 1.0:1 did not change. There was no disturbance.
2) The Super "C" was relocated adjacent to a steel wall 18 feet high and 50 feet long. At a distance of three feet the VSWR 1.0:1 did not change. At two feet the VSWR increased to 1.5:1. Hard to believe!!!, but true.
3) The antenna was then placed inside a steel building. The Building had no windows, steel roof, sides, and doors. All doors were closed and 100 watts was applied to the antenna. The antenna remained resonant and VSWR at 1.0:1.
4) A second test antenna has been operating now for months in an attic over a residential garage. It is two feet from the attic light and positioned between the trusses, over the house wires, the garage ceiling lights and the garage door opener. The transmitted power was 100 watts. The sole interference detected, was on the portable (40 MHz) phone!! Prior to attic operation, the Super "C" had been placed five feet from a GAP vertical. Neither antenna detuned the other.
Earth Loss - The surface area of the collector-grid is much larger than the basket. Actually about double. The capacitance equation clearly states "do not expect more capacitance than that from th smallest area", or in this case the basket. Thus, the antenna does not look "beyond" the oversized collector-grid or the ground. A second factor is the charge on capacitor plates is only on the s es that face each other, thus the under side of the collector-grid is "NEUTRAL".
Rationales are interesting, but does the real world confirm? A Super "C" antenna was mounted on a three foot insulated mast, and matched to a 1.0:1 VSWR. The antenna was then raised to 11 feet, nd the VSWR did not change. If the Super "C" had picked up some Earth loss at three feet, it would have diminished at 11 feet and the resultant VSWR should have increased. Since it did not the c clusion can be drawn that Earth loss would not be a factor. The antenna was then lowered directly to the ground and VSWR was measured once again and no change was indicated.
To verify that the underside of the collector-grid is neutral, take a fluorescent bulb and while transmitting, touch the bulb to the top side of the collector-grid at the edge and it will light. ow place the bulb on the under side of the grid and touch it to the edge and it will not light. The antenna resistance was measured and calculated at 2.8 Ohms. Which leaves little room earth loss
Efficiency - The large capacitance inherent in a Super "C" drastically reduces the antenna's capacitive reactance thus eliminating the need for a large coil. A very small coil, four turns of tw ch diameter is used on 20 meters. This small air wound coil is virtually loss less. This and the absence of earth loss results in an antenna efficiency that approaches 100% in spite of its low pr ile.
The Super "C" was A/B tested against a full size 17 foot conventional vertical with three insulated full 1/4 wave radials. At no time did the signals received on the conventional vertical exceed e Super "C"'s. On numerous signals, the Super "C" was as much as two "S" units stronger. If 60 1/4 wave radials (1020 feet) were deployed, it would have decreased earth loss from 35 Ohms to four ms increasing the conventional vertical's signal by half an "S" unit, but still less than the Super "C".
What you have just read is just a very small portion of the Super "C"'s characteristics. As time passes, what we know today about EDR antenna will have been just the tip of the eventual iceber
73's
GAP