- An antenna has the task either to transfer energy from an electromagnetic field (receive) or to transfer the energy from a high frequency-generator (transmitter) to an electromagnetic field.
- The beginning of an antenna was the half-wave dipole, which still today is widely used. As the name expresses its length equals half of the wavelength of the frequency to be used. In this case the dipole is resonant. The information given below refers as well to antennas like yagies, different kinds of ground planes, loops, etc.
- We call "an antenna is in resonance" when its impedance is real. That means: The power supplied meets a pure resistance, which is a combination of radiation resistance and loss resistances. An antenna is in resonance for only one frequency and its harmonics. In deviation from that you will have additional reactance that can be seen as inductivities or capacities in series. They do compensate in case of resonance.
- You can consider an antenna as an resonance circuit. Even there equal reactance of L and C when in resonance, they do not exist any longer because each reactance compensates the other. And an other regularity for resonance circuits also applies to antennas: The higher the inherent Q the better the efficiency. But at the same time there is the rule: The higher the inherent Q the narrower the resonance range.
- Operating antennas beyond its resonance frequency leads to reactive impedances. This has to be avoided because reactances do not help to transfer electric energy to radiation. Another aspect has to be considered, namely the antenna's input impedance.
- Antenna impedance should not only be as real (ohmic) as possible, it should also become as close as possible to the transmission line impedance to avoid mismatch. If that cannot be guaranteed you will get the effect of reflected power on the feeder, which causes that the transceiver sees a load impedance which may be far away from its specified value. As a result you may get enormous losses in the transceivers output circuits and in the transmission line, both might lead to damages.
- Antenna matching units have the goal to match antennas with transmission line or transceiver impedances respectively. Preference is to do the matching as close to the antenna as possible. Our SAMS (Swiss Antenna Matching System) offers the most comfortable realisation. Another variation is to use a desktop antenna matching system produced by Palstar, which we sell as well.
- A very interesting possibility offers our SAMS to match Titanex Verticals for all frequencies between 30 to 160 meters. Please ask for information if you are interested in getting a full tuneable Vertical.
- Follow this link to get more information about experiences that led to the development of SAMS.