From：Zhaoqing Xiangjiasheng Technology Co., Ltd Release time：2020-11-21
Combining industry experience, rich theoretical knowledge, and the practical operation of R&D and mass production, Xiangjiasheng Technology has sorted out the matters needing attention in antenna design for you.
The use of tracking antennas in RF product design has several advantages. At frequencies> 900 MHz, good performance, low cost and small size are a few examples of the popularity of tracking antennas. When implementing tracking antennas, remember these 7 keys to make your antenna design flawless.
1. Understand the common antenna types available
Widely available standard designs include unipolar, L-type and F-type. Standard F antennas are the most widely used and provide the best compromise between size, efficiency and omnidirectionality. You can use winding traces to compress the PCB area, but this comes at the cost of performance.
2. Consider the structure of the circuit board
The length of the PCB trace will determine the resonant frequency; the length of the trace on the circuit board will determine the resonant frequency. The higher the frequency, the shorter the trace. Each antenna needs to reserve a certain area on the PCB. This is defined as the area around the antenna traces, in which copper traces or ground fills cannot be used on any layer of the PCB. The wider the trace, the better, because they usually provide a wider bandwidth. The traces can be gold-plated or covered with solder mask. The electrical properties of the antenna will be determined when the substrate material is used, its thickness and dielectric constant (ε-[R).
3. Ground plane is very important!
PCB trace antennas depend on the ground plane because they must have an effective ground plane. The shape and size of the ground plane relative to the antenna will affect the impedance and performance of the PCB antenna. The ground plane should have vias on the entire edge of the antenna to keep it away from the area.
4. Always include matching components
Mismatched antennas will greatly reduce the overall RF link budget and range performance. Make sure to incorporate a pi network placed directly at the antenna feed point to prevent unnecessary mismatch losses.
5. Beware of the environment where the antenna will be used
The presence of plastic housing, metal components, and other components close to the antenna will affect the rotation and radiation pattern of the antenna. Do not bring the antenna close to metal objects, and do not use metal or metalized plastic enclosures. Ideally, keep external influences in the far field of the antenna.
6. Each application needs to be debugged
All PCB antennas are specific to the circuit board, and each implementation requires a certain size and matching degree. Duplicating an existing design cannot ensure good performance. The gain and radiation pattern will change as the parameters in the surrounding area change. The length of the antenna will need to be adjusted according to these variables. In addition, the final adjustment and matching should be completed in the shell and installation of the final product, not in the open air environment.
7. Antenna matching is a must!
When the antenna impedance matches the source impedance (50 ohms), the maximum RF power will be transmitted. Consider the return loss of <-10dB as the quality factor for good antenna matching. This means that 10% of the incident power is reflected due to the mismatch. The return loss of the antenna is characterized by measuring the reflected power at the antenna feed point (plus matching components). The antenna is disconnected from the transceiver, and the network analyzer is connected to the antenna via a coaxial cable to perform the measurement. Remember that when the antenna is placed in the location and environment used during normal operation, it must be tuned.
Finally, to summarize, whether it is active or passive, matching must be done. This refers to the matching of chip modules or motherboards, so that the antenna can be designed completely and accurately.