Antenna impedance
As AnTune gives you possibilities to design antennas that have rather unexpected and extreme impedances
is it a common question if antenna not needs to have 50 Ohm resistance to be maximum effective.
Answer is no. There is nothing magic with the number 50 that the antenna has benefit of.
There is however a lot of practical impedance limits. A matching network main function is to present a matching impedance that allows for maximum transfer of available RF energy. By keeping the required impedance transfer ratio low, will it make matching network less complex, less critical and by that also less lossy part of the total transfer chain.
As most RX and TX equipment are designed for 50 Ohm, is it therefore better to design an antenna that also is 50 Ohm, as then is no matching network needed at all and losses due to not ideal matching components can be avoided.
Answer is no. There is nothing magic with the number 50 that the antenna has benefit of.
There is however a lot of practical impedance limits. A matching network main function is to present a matching impedance that allows for maximum transfer of available RF energy. By keeping the required impedance transfer ratio low, will it make matching network less complex, less critical and by that also less lossy part of the total transfer chain.
As most RX and TX equipment are designed for 50 Ohm, is it therefore better to design an antenna that also is 50 Ohm, as then is no matching network needed at all and losses due to not ideal matching components can be avoided.
Impedance/bandwidth problem
Designing a close to 50 Ohm antenna, with good efficiency, covering several bands that fits in a too small antenna volume inside a plastic box, remain stable for hand effect, is maybe the design goal, but too often practically not possible. Several antenna designers tries to make the antenna work over a wider frequency range, and still keep an impedance close to 50 Ohm by adding secondary radiators or improve impedance matching by adding stubs inside antenna structure. It work to a certain degree but these extra structures does also cost antenna volume mainly for the part of antenna structure that should cover lowest frequency part. Above this, for cell phones does wished antenna bandwidth increase for each year, while antenna volume is shrinking.As there is a relation between available space and antenna efficiency, some parts of the antenna must suffer.
AnTune solution
With AnTune you can in many cases avoid these extra structures and use a single antenna element that fully use existing antenna volume. Bend and adjust this structure a few alternative ways while letting AnTune dynamically update a optimized matching network for that antenna structure.You can live see what impedance matching that results in best bandwidth and how the antenna structure should be adjusted to achieve an antenna impedance that don't require too extreme impedance ratio.
Which antenna solution that normally works best for a given situation, if it is a PIFA or any other type of antenna, close to ground or not, is up to the antenna designer knowledge to select.
When antenna type has been selected, is it time to start AnTune and make a good measurement calibration. Within a few minutes later you have found more possibilities to reach specified antenna goal then you ever seen before. From all these possibilities try select a solution that requires a not too complex matching network. Implement this network and you are very much done with this antenna.
It is a simplified description of a possible work process. It still requires a lot of experience to be able to bend or cut shapes to something that results in an antenna that radiates in a certain way. AnTune do not remove any part of antenna design process but antenna useable impedance area in Smith diagram is with aid of AnTune 100 times bigger which drastically improves possibilities to find a good solution.
Actual antenna impedance is a secondary problem and more effort can instead be done in optimize other antenna properties.
Development time
A good multiband antenna takes more than minutes to design. Sometimes it is weeks or months. Some antenna requirements will remain unrealistic to reach even with aid of AnTune. However, if there is an possibility to find a antenna solution, is it realistic that with aid of AnTune the antenna shaping and calculating matching network can be done in half of normal development time and most likely also reaching better total antenna performance then with conventional antenna design methods.There is another thing that AnTune will simplify: Measurement calibration.
But only if it is correct performed. Without good calibration, is it no use of AnTune as it will show one solutions but reality will be something else.
Value of doing correct calibration is too often underestimated or partly misunderstood .That it is why these pages are full of basic tips how to improve calibration procedure.