When developing a new wireless device, electrical engineers need a significant amount of time to design all the circuitry and the PCB layout. Very often the design of the antenna ends up at the last part of the project. Unfortunately, antennas, compared to the other passive components, like capacitors, resistors and inductors, need more attention.
Why was there a need to develop TELA antennas?
According to industry standards, the feeding line to an antenna should be 50 Ohm. However, an antenna itself does not have 50 Ohm impedance. Therefore some additional adjustments need to be done. This process of adjustment for antennas is called tuning.
Tuning is important for several reasons. Tuned antennas can transmit more power while consuming less energy (the return loss data is below -10dB), the distance between the transmitter and receiver can be longer, and the gain and efficiency are higher.
When using chip antennas, there are many methods of optimization. To see the results during the optimizing process, we use some network analyzer to see the return loss data (the lower the return loss the better) or Smith chart (from resistance and reactance at the desired frequency, one knows how to optimize the impedance) or at least perform impedance measurements to get 50 Ohm of the system (from the feed line to the antenna).
The simplest method of tuning a chip antenna that does not require any engineering background is to prepare different sizes of mother PCBs, see which one works the best, and start cutting the length of the PCB to get the best results possible.
The engineering approach is to measure the impedance of the chip antenna on the device and calculate what impedance of the feeding line can match the chip antenna to 50 Ohm of the system.
The third approach is to use standard metal trace and optimize the impedance through a PI matching circuit. Pi matching is possibly the most selected option by antenna engineers. Using a network analyzer, it is easy to change the passive components (usually there is a maximum of three components) to get 50 Ohm of the system with a chip antenna. With PI matching, we do not need to use time consuming calculations for the feed line.
But through intense research and testing, Unictron has devised a unique and patented design for a TELA chip antenna.
TELA chip antennas also use PI matching circuits to tune the impedance of the system, but add another (one or more) tuning element for adjusting the resonance frequency of the chip antenna. The complexity of tuning is the same as when using only a PI matching circuit, but with benefit of additional efficiency and gain improvement of the antenna. Also this fine tuning element is very useful in difficult cases when the antenna is implemented in the last part of the project design.
TELA stands for Tuning Element Loop Antenna. To understand the meaning of “loop” and “tuning element”, let us review the two pictures below.
In the first picture, we can see a typical layout of a monopole type chip antenna. Tuning of this antenna type is done through optimizing the PI circuit and size and the shape of the ground clearance area.
In the second picture, we can see a typical layout of the TELA antenna.
The feed line goes to the chip antenna through the PI matching circuit. The other end of the chip antenna is connected to the ground through the tuning element. With careful observation of the left size of the chip antenna’s left side, you will find out that the chip antenna is connected to the ground also on the left side, creating a short circuit. That is another unique feature of TELA antennas.
Advantages of the TELA antenna compared to other chip antennas
The patented design of TELA antennas brings many a lot of positives for the project design stage. The same layout of TELA antennas can be used on different PCBs for of different projects. This means that an electrical engineer can simply need just copy and paste the layout without requiring extensive knowledge and doesn’t need to know anything of about the antenna. In effect, aAntenna tuning can be done in the last stage of the project with great results.
If we compare monopole antennas and TELA antennas, we can see that TELA antennas requires a smaller clearance area yet maintain and still keeping a good performance. Smaller clearance area means that other electrical components can be arranged put closer to the antenna and closer to each other, resulting in a compact device. This is eEspecially useful in portable devices that can then be reduced even smaller in sizewhich can be then even smaller.
The loop design of the TELA antenna uses a is using magnetic field in the near field for the radiation, while t. Traditional monopole antennas use an are using electric field in the near field. This is a great advantage because mMagnetic fields are is being less influenced by the presence of a human or animal body, making which makes TELA antennas the best choice for wearable and other portable devices.
Antenna tuning made easier than ever
With TELA antennas, tuning can be done by anyone with a who has a solder and soldering device. There is nNo need to have a deep knowledge of antennas. At the beginning, do your regular PI matching and follow the instructions for the tuning element in our datasheet. You only need to change the value of the tuning elements, which can be done without complicated math calculations. After 3 or 4 attempts,Maybe 3-4 tries and you will get a perfect performance of the antenna by yourself. For the best results, we would still recommend sending the device to Unictron for deep testing in 2D and 3D anechoic chambers and then decide deciding the best values of the tuning elements.
Professionals can also consider the advantage of tuning elements that for second generation of the devices., Wwhen few parts of the circuit board are changed, there is no need to re-consider a the new suitable antenna. Simply Only change the tuning element and the antenna will be optimized in the new device as well. In traditional methods, ways you would have to consider new antennas or new PCB layouts when newly added electrical components are introduced to the electric circuit. But with TELA antennas, you can deal with the device as a whole, knowing that wireless connectivity will perform very effectivelybe good.
TELA type chip antennas are available for WiFi, Bluetooth, GPS, GLONASS, Beidou, Galileo, LTE diversity, 868MHz, and 915MHz.
Upon request we can prepare tuning for other frequencies as well.