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Meaning of the resonance on the operating frequency.

 

The best transfer of the RF power in the Aether (maximum antenna efficiency) is guaranteed by the perfect resonance of an aerial on its operating frequency.

Many Hams erroneously still believe that a condition of 1:1 Standing Wave Ratio (SWR) indicates the perfect resonance at the operating frequency. It must be remembered that this ideal SWR condition tells us that the impedance at the antenna feeding-point is equal to the feed line impedance (normally 50 Ohms).

 

What tell us the real true facts about the resonance at the operating frequency of our antenna, instead, are the following parameters:

 

- Impedance

- Radiation resistance

- Reactance

- Phase

 

Traditional fixed-length yagis present their best resonance only on a specific frequency of its operating-range and a specific fixed band-width strictly depending from the operating frequency and the diameter of the antenna element.

To make short a long story, let's make an example of an antenna resonant on 7,100 MHz. If we graually increase the operating frequency, the antenna will gradually show an increasing inductive-reactance (Zin + Jin). This because the antenna will gradually become longer and longer at each new operating frequency. If we gradually decrease the operating frequency, instead, the antenna will show a gradually increasing capacitive-reactance (Zin - Jin) because it will gradually become shorter and shorter at each new operating frequency.

When we start getting higher or lower than 7.100 MHz, the values of the remaining parameters will begin to become more and more un-ideal. If we take a look at the phase (comparison between Current and Voltage) we see that, inevitably, it will change the ideal value as we operate either higher or lower than 7.100 MHz. The final result will be an inevitable discrepancy around the ideal 50 Ohms.

We wanted to write these very few and simple lines to introduce you a series of graphs to show you how the parameters of a conventional length-fixed antenna do change in comparison with an Ultra Beam antenna when the operating fraquency is varied.

Please note that the measurements have been made on a full-size 40-meter monoband resonant on 7.100 MHz and a 6-40 meters UltraBeam antenna.

The graphs show the devastating difference between the two aerials as the frequency is varied around the reference 7.100 MHz. They show the drastic variations of values evidenced by the monoband while the Ultra Beam shows almost unappreciable changes along its operating range. The difference between the two aerials is so big that if we wanted to represent all parameters on a single graph, those relative to Ultra Beam could only be represented by very flat lines. If this does not make Ultra Beam magic, it certainly shows that it is is the closest ever antenna to the theoretical one treated in the antenna-manuals.

We hope that our new way to introduce the above arguments and the prerogatives of an antenna that has the ability to be always perfectly resonant on each Kilohertz of its operating-range, may explain the reasons of the disarming difference between the performances of a conventional fixed-length antenna and ours.

Every Ultra Beam owner, infact, has already changed his own mind about the mythical monobanders.

 

PLEASE NOTE: Please, pay due attention to the values raspresented by each curve.

Example:

 

The two graphs below show that the resistance values of the monobander range within 85-100 Ohms

while the same parameter of Ultra Beam ranges within 50,3-50,8 Ohms in the whole range 7,0-7,2 MHz.

 

 

The two graphs above show the very large differences between the two antennas. The graphs show that the values of the monoband antenna change very drastically if compared to those of the Ultra Beam. The difference between the two antennas is so large that, If we would lay the graphs of the Ultra Beam upon those of the monoband antenna, all parameters could be represented by an horizontal lines only, as if it were a true theoretical antenna.

 

 

The software we have used did not permit two antennas to be "plotted" simultaneously, but a "manual" overlap will show us two graphs which represent a very disarming difference between the Ultra Beam and the monoband. The yellow lines show the ideal values of Ultra Beam within the entire frequency-range represented on the graphs below and not only. The best "Resistance" and "Reactance" values of the monoband antenna are contained within an incomparable limited frequency-range. These differences, of course, are much bigger if we compared our antenna with any "trap" antennas.

 

 

We are sure that our "unusual" way to explain the true importance of an effective resonant antenna will permit you to better appreciate and understand that the advandages of Ultra Beam over a conventional length-fixed antenna are not limited to the possibility to reach the faithful 1:1 SWR only.

 

 

Ultra Beam wanted to make a comparison with a monoband antenna because such an antenna is STILL considered the best performing antenna by many Hams worl-wide. We want to remind you that the Ultra Beam used in the tests shown above has shown the amazing "flat" response indipendently of the operating frequency with in 7,000 - 28,000 MHz. Its perfomances have shown to be better than 7 monobanders designed for each of the actual 7 international bands comprised in its operating frequency-range.

Last but not least UltraBeam is a true general coverage antenna in its entire operating frequency range.