The coaxial cone serves several important functions. In some ways it does mimic a transmission line with it's ability to confine or shield radiation from the base of the center vertical radiator. Because it's tapered, it transforms the impedance of the antenna so that it can be efficiently matched to 50 ohm coax. The cone is also tuned to act as an effective counterpoise and has both transmission mode and antenna mode currents flowing through it. Transmission mode currents are confined within the cone and antenna mode currents are allowed to radiate constructively on the outside of the cone.

Let's examine how this principle allows us to simulate a collinear antenna. Normally the end fed antenna will begin to radiate from its base in a phase that is deconstructive once the wavelength is increased significantly beyond 1/2 wave. Pass this point and the peak gain begins to shift in favor of an upper 45 degree lobe where it is wasted. This is why it is essential to confine the radiation from the lower 1/4 wave section of the center vertical element. Allowing the longer top section above the cone to radiate constructively with the currents on the outside of the cone.

Dominator NWE-34 radiation currents displayed
in CST model pictured on left.

Advancements in computer antenna modeling software have made it easier to understand how the Dominator NWE-34 produces more gain then any single other commercially manufactured FM broadcast antenna. CST Microwave Studio is an exceptionally accurate software tool that provides 3D Electro-Magnetic simulation of antennas. The image displays both the magnitude and phase of all radiation currents along the antenna at a driven phase angle that produces maximum current. Clicking on the image above and to the left will open a GIF video that shows the currents at all driven phase angles throughout the 360 degree RF sinewave.

Magnitude is displayed with color intensity and referenced to the chart on the right. This chart shows the magnitude in amps per meter for the corresponding colors. Phase is also indicated by opposing colors at the positive top and negative bottom of the chart. The Dominator has obvious characteristics not typically found in antennas other then collinear types. It has 3 separate radiation currents with two allowed to radiate freely in a phase that is constructively combined in the far field. The third current is in a deconstructive phase with respect to the other two and has been confined within the tapered coaxial skeleton cone.

It is the tapered 1/4 wave coaxial cone that sets this antenna apart from others. It allows the longer top section of the main radiator to radiate freely while the deconstructively phased radiation on the lower 1/4 wave of the main radiator is confined within the cone. Since the base of the cone and the base of the main radiator are excited by opposite phase polarities, the currents allowed to radiate on the outside of the shielding cone combine constructively with the longer main radiator extending above the cone. Total currents radiated by the cone are divided into its four vertically tapered radials. This provides noticeable gain over a dipole on the distant horizon.

Understanding the Cartesian radiation elevation charts.

Now that we have covered how the CST model reveals radiation currents from the tapered coaxial cone and upper main radiator constructively combine together, lets look at how this compresses the Dominators beamwidth in the far field to produce it's 3 db gain over the dipole. The Cartesian charts show the normalized field in relation to the elevation angle above and below 0 degrees horizontal. Normalized field is the technical term for the relative amount of field power density the particular antenna can produce at the given elevation angle, with 1 being equal to 100% of its maximum radiated RF field. Clicking on either image above will open a larger version.

The half wave dipole shown in red has a broader less compressed slope then the Dominator shown in blue. This wastes power by radiating it well above and below the horizontal plane. The dipole is still radiating 50% of it's maximum field at an angle that is -60 degrees from horizontal. In comparison, the Dominator field is reduced to 50% at an angle of -47 degrees from horizontal and it's down to 33% at -60 degrees. Effectively refocusing the power wasted at undesired angles into a tighter beamwidth that is 3 db stronger then a dipole at the critical 0 degree elevation angle.

Because the Normalized fields are relative to the specific antennas full power field, it is not apparent how the beamwidth effects the two antennas Effective Radiated Power in comparison to each other. We only see the percentage of the individual antennas full field at any given angle. If we were to lay the dipole chart over the Dominator chart and used the Dominators Normalized Field as the reference point for peak field power, the differences would be clear. 

The peak field for the dipole would only reach approximately 0.75 or 75% of the Dominators peak Normalized field. Placing it 3 db lower as a result of wasted energy at angles that are not useful to VHF broadcast propagation. The Dominators compressed beamwidth not only increases gain, it reduces on site RF exposure levels with limited downward radiation making it easier to comply with safety standards.

The Dominator® antenna was developed for FM Broadcast in 1996 by Norwalk Electronics. It is a high gain vertically polarized .82 wave Coaxial antenna. It is the coaxial cone at the base of this antenna that allows us to go beyond the standard 1/2 wave and 5/8 wave designs while forcing the angle of radiation down on the horizon. The Dominator® has the same vertical gain as four stacked circular polarized bays fed in phase and mounted over a forty foot section of tower.

This antenna uses a highly efficient Teflon insulated gamma match that eliminates any coils or matching transformers. That enables shunt feeding of the .82 wave main radiator, keeping it DC grounded for added lightning protection. This also gives the antenna it's ability to handle high power levels. The standard model is available with a gold pin Teflon insulated weatherproof N or SO-239 connector recommended for up to 1 KW input. Higher power versions are also available such as our 3 kilowatt using a Teflon 7/16" DIN connector and heavy duty gamma match.

Beware of poorly constructed clones that look similar to the Dominator®. One distributor in Slovenia is selling an antenna that has been made to look like the factory authorized product . Clones are not factory authorized and are advertised with inflated gain figures. Please visit our "Dominator vs. Clone" page for more information. Norwalk Electronics guarantees no single other FM broadcast antenna can produce a stronger signal or you can return the antenna to us within 30 days for a refund.

The Dominator® is professionally manufactured using high grade 6063 magnesium alloy aluminum tubing. This antenna is currently in use by hundreds of stations around the globe from Alaska to South America. It has proved itself to withstand severe weather while providing a strong reliable signal.

The Dominator® also offers unique possibilities for use in emergency or temporary situations where an effective, easy to install antenna is required. Be prepared for the unexpected as changes in weather patterns can cause a severe weather system to strike at anytime. This has forced some stations into the awkward position of having to reach their listeners after the loss of the transmitter antenna and or tower.

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