TELA chip antennas
When developing a new wireless device, electrical engineers need a significant amount of time to design the circuitry and PCB layout. Very often the design of the antenna ends up being the last part of the project. Unfortunately, antennas, compared to the other passive components, like capacitors, resistors and inductors, require more attention since they interact with surroundings and require adjustment or “tuning” according to the environments in which they are being used. Especially, the dimensions of the ground plane as well as components and circuitry on the circuit board have significant influence on the performance and characteristics of antennas. The process of adjusting the frequency or impedance of antennas is called tuning. According to industry standards, the impedance of the feeding line to the antenna should be 50 Ohm. However, the antenna itself does not always have 50 Ohm impedance. Therefore, tuning becomes an essential part of design-in of the chip antenna on the circuit board.
Tuning is important for several reasons. Tuned antennas can transmit more power while consuming less energy, therefore higher antenna gain and efficiency can be achieved and the distance between the transmitter and receiver can be extended. When using chip antennas, there are many methods of optimization. Unictron normally uses network analyzers to examine the return loss data or Smith charts to determine how to optimize the antenna design to obtain the ideal 50 Ohm impedance from the feed line to the antenna. Using data from the network analyzer, it is easy to change the passive components (usually there is a maximum of three components in the Pi circuit) to get 50 Ohm with a chip antenna.
The TELA antenna innovation
Rooting on our extensive experience and knowledge of antenna, Unictron has developed a unique and patented design of TELA chip antenna. TELA stands for Tuning Element Loop Antenna. Below we elaborate on the meaning of “loop” and “tuning element.” TELA chip antennas use Pi matching circuits to tune the impedance, but add another element or a few more tuning elements to adjust the resonance frequency of the chip antenna. The complexity of tuning is the same as when using only a PI matching circuit, but results in the additional efficiency and gain improvement of the antenna overall. This fine tuning element is very useful in difficult cases when the antenna is implemented in the last part of the project design. Let’s discuss in more details below: In the Figure 1, 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 Figure 2, 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 side of the chip antenna, you will find that the chip antenna is also directly connected to the ground plane, creating a short circuit. That is another unique feature of TELA antennas.
Advantages of our unique TELA chip antennas
The patented design of TELA antennas brings a lot of positives for the project design stage. The same layout of TELA antennas can be used on different PCBs for different projects. This means that an electrical engineer can simply copy and paste the layout without requiring any knowledge about the antenna. In effect, antenna 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 an excellent performance. Smaller clearance area means that other electrical components can be arranged closer to the antenna and closer to each other, resulting in a compact device. This is especially useful in miniaturization of portable devices. The loop design of the TELA antenna uses magnetic field in the near field for the radiation, while traditional monopole antennas use an electric field in the near field. This is a great advantage because magnetic field is being less influenced by the presence of a human or animal body, making 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 solder and soldering device. There is no 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. To adjust the frequency, one need to try out capacitors with different capacitances (reference is shown in the datasheet of each TELA antenna), to get the desired center frequency. Normally 3-4 time changes in matching combination may be needed to get a perfect performance of the antenna for each new device. For the best results, we would still recommend sending the device to Unictron for a complete testing in 2D or 3D anechoic chamber to get the optimal performance of chip antennas. When some parts on the circuit board are changed in the revision or a new model, there is no need to re-consider or re-evaluate a new antenna. Simply by changing the tuning element, the antenna will be optimized in the new device as well. In comparison, when using printed antenna on the circuit board, you may need to do a complete redesign when new electric components are introduced to the circuit board. But with our patented TELA antennas, the layout stays the same, no matter the changes on the board.
Unictron offers TELA type chip antennas for Wi-Fi, Bluetooth, GPS, GLONASS, Beidou, Galileo, LTE diversity, and sub-giga frequencies like 868MHz or 915MHz. Upon request our antenna experts can develop TELA antennas with other frequencies as well.