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- How Do the Isotrons Work?

This is a very common question from those that have not seen the ISOTRONS in action. Even those that have, ask it with amazement. Well, it's not magic. 

The ISOTRONS have been developed around specific electrical laws and laws of physics. At times, the eye can be deceived so that something may look like it is against known laws or what we know as practical. 

For an antenna to work, it should be electrically resonant. The ISOTRONS are electrically resonant by using only two components - the large coil in series with the capacitive plates of the antennas. (Match comes automatically with the right combination of the two components at resonance). There is more that is necessary for an efficient antenna. An antenna needs a certain amount of area to couple radiation to the atmosphere. Some call this the "Capture Area". However, this is an "AREA". This "area" can be any shape or form. The laws of physics for this phenomenon do not specify its appearance. THE ISOTRONS HAVE THIS RADIATION "AREA". The ISOTRONS exceed or equal (depending upon the model) the area of a conventional one-half wavelength dipole (#12 wire). In simple terms, we designed the ISOTRONS into a three dimensional package. 

THE PERFORMANCE - It speaks for itself. Tests have measured the ISOTRONS to transmit as well as a one-half wavelength dipole. The shape of the ISOTRONS give them an excellent advantage for the reduction of noise. The ISOTRONS have been tested at 3db less noise on reception with an equivalent incoming signal as the one-half wavelength dipole. In the six antenna Reviews, one characteristic was definitely distinctive of the ISOTRONS: THE PERFORMANCE. The ISOTRONS were developed around known laws to accomplish an efficient performing antenna in a very convenient package.


The purpose of the design was to make a compact, convenient design that would perform well. The design is an electrical copy of a 1/2 wave dipole. I will describe electrically what takes place. Radiation patterns and formulas are not necessary for analyzing the tuning characteristics. 

A 1/2 wave dipole reacts as a SERIES RESONANT CIRCUIT. All electrical formulas you want to apply to this circuit will also apply to the antenna AT THE FEEDPOINT. The feedpoint is what determines how the antenna will match the transmitter and measurements are taken at the connector of the antenna. Therefore whether the circuit is on your radio board or hanging as an antenna all formulas and theory apply. 

At the feedpoint the dipole or Isotron will resonate. This is when the Capacitance Reactance (XC) and Inductive reactance (XL) are equal (value in ohms). However when this takes place, because the antenna is a radiator it will also develope a pure RESISTANCE (R) when resonant or Radiation Resistance. This R is dependent on the antennas grounding, feedline and environment. This R value is what establishes your SWR measure at resonance. Once an antenna is resonant it becomes a working device with a radiation resistance of 25 ohms or greater.When the antenna has a higher XC value than the XL the antenna is off resonance. The resonant point is at a higher frequency than where the transmitter is currently set. If the XL is greater than the XC the opposite is true. Off resonance the Impedance (Z) of the antennas increases. It will be at its lowest value at the resonant point. (Z and R are not the same).  

Testing an antenna at the feedpoint without the feedline is fine for design work, but is not practical for tuning it to your entire set up (radio, feedline and grounding). The antenna is an infinite extension to your feedline. They both must be tested together to have reliable results.

The Isotrons have been built physically to have proper capture area to the atmosphere. Enlarging the antennas more will have little affect on performance. 

The Isotrons are not a loop. Therefore the radiation pattern is omni‑directional and polarization is random. This offers excellent efficiency on transmit. Reception is noticed as soon as the receiver is connected. Low noise, good sensitivity and the affects of changing polarization is lower. 

Granted it looks a little strange compared to what we are use to. However the advantages are plain to see. Our 41 years of service to the HF community is a testimony to the performance of the Isotrons

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