Antenna design and RF layout are key components in wireless systems that are responsible for sending and receiving electromagnetic radiation from air. The wireless range obtained from a RF product (such as a limited coin battery having a power supply) mainly depends on the design, housing and good PCB layout of the antenna.
For chips and power supplies, the layout and antenna design is different, and their RF (radio frequency) ranges are also normal. This application note describes the best practices, layout guidelines, and antenna debugging procedures, and gives the widest band using the given power. Radio frequency tracking, power supply decoupling, passage hole, PCB stack, and overall layout of antenna and grounding have also been discussed. Application notes also describe the choice of RF pass-throughile (such as inductor and capacitors). Each topic ends with a prompt or check the table of design items related to the subject.
Figure 1 shows a key component of a wireless system on a transmitter (TX) and receiver (RX).
Designed an excellent antenna to expand the work range of wireless products. The larger the energy transmitted from the wireless module, the larger the distance between the transmission of the packet error rate (PER) and receiver sensitivity is fixed. Similarly, the tuning radio on the receiver side can operate on a very small radiation condition on the antenna. The RF layout takes place along with the wireless matching network to be properly designed to ensure that most of the power reaches the antenna from the RF, and vice versa.
Antenna principle
The antenna generally refers to the conductor in the space. When the length of the conductor is a specific ratio or an integer multiple of the signal wavelength, it can be used as antenna. This condition is referred to as "resonance" because the electrical energy supplied to the antenna is transmitted to the space.
As shown in Figure 2, the wavelength of the conductor is λ / 2, where λ is the wavelength of the electrical signal. The signal generator is powered by a central point of the antenna via a transmission line (also known as antenna feed). According to this length, voltage and current station will be formed on the entire wire, as shown in Figure 2. The electrical energy input to the antenna is converted to electromagnetic radiation and radiates to the air at the corresponding frequency. The antenna is powered by antenna, and the feeding characteristic impedance is 50 Ω, and radiated into a space of the characteristic impedance of 377 Ω2. Therefore, there are two very important matters for the geometry of the antenna.
Antenna length
2. Antenna feed
An antenna having a length of λ / 2 (as shown in Figure 2) is called a dipole antenna. However, in the printed circuit board, most of the conductor lengths used as the antenna are only λ / 4, but still have the same performance. See Figure 3 for details. The same mirror (λ / 4) as the conductor length can be created by placing the ground layer at a distance below the conductor. These pins are used as a dipole antenna when they are combined. This antenna is called a quarter wave length (λ / 4) antenna. Almost all antennas on the PCB are achieved in a quarter wavelength of the copper ground plane. Note that the signal is now single-end feed, and the ground layer is used as the return path.
3.
For the quarter wave long antenna used in most PCBs, special attention is required:
Antenna length
2. Antenna feed
3. The shape and size of the ground plane and the return path
Be
The type and selection of antennas in the RF RF circuit
How to consider the antenna parameters in the RF circuit
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