Smartphones, routers, IoT systems or drones – today, almost every device communicates wirelessly. Behind every data packet sent “through the air” is an antenna. Simply put, antennas and wireless communication are an inseparable duo. A key component that transforms an electrical signal into an electromagnetic wave – and vice versa. Although often hidden inside the housing, it determines the range, signal quality, and reliability of transmission. It’s worth remembering that even the best transmitter won’t help if the signal is not properly emitted or received.
What does an antenna do and how does it work?
An antenna is a “gate” between an electrical signal and an electromagnetic wave, transforming one into the other. During transmission, it generates an electromagnetic field that detaches and propagates as a radio wave. During reception, the wave induces a signal in the antenna, which goes to the receiver. The antenna should be tuned to the operating frequency, and its length should correspond to a fraction of the wavelength. Such tuning, called resonance, improves the efficiency of signal radiation. Antennas working in a circuit require a counterbalance or second pole, such as a ground plane, housing, or copper on a PCB, to operate properly. Understanding the principles of the programming of integrated circuits, especially those with wireless communication modules, is also important.
What types of antennas are there, and when are they used?
In the production of electronic devices with compact dimensions, antennas are used to accommodate limited space.
- Half-wave dipole consists of two quarter-wave arms. Often used as an external omnidirectional antenna, e.g. in drones. Requires impedance matching.
- Quarter-wave monopole (rod or helical) radiates omnidirectionally in the horizontal plane. Requires a ground plane as a counterweight. Commonly used in remote controls and routers.
- Antenna printed on a PCB is a copper trace (straight, meandered, or looped) without additional components. It is inexpensive but requires a metal-free zone and occupies space.
- Chip antenna is a ready-made SMD ceramic component. It takes up little space but requires proper board and ground design.
- IFA and PIFA are types of antennas commonly used in smartphones and Wi-Fi modules. They are compact, less sensitive to hand interference, and often tuned to multiple bands.
- Patch antenna (a type of directional microstrip antenna) is often used in GPS applications. It offers directional gain with small dimensions.
- Directional antennas (Yagi, panel, parabolic) focus energy in a single direction – used in long-range connections.
Most antennas in portable devices are variations of these types.
Antenna parameters – what affects range and signal quality?
When designing electronic devices, it is important to take into account several factors that influence range and signal quality:
- Operating band defines the frequencies for which the antenna is designed. Antennas that are not tuned to the correct range have low efficiency. Multiband antennas can operate at various frequencies, but this reduces efficiency.
- Impedance, often 50 Ω, is the electrical value that should match the transmission path’s impedance to ensure signal transfer without reflections and with maximum efficiency.
- Antenna gain (dBi) defines the directionality of the radiation.
- Polarization refers to the orientation of the electric field of the electromagnetic wave emitted by the antenna.
- Bandwidth indicates how wide a range of frequencies the antenna can handle.
- Efficiency indicates how much of the input power is actually radiated.
How to position the antenna in order to improve range?
- The antenna should be placed away from obstacles and metal elements, which can cause reflections and interference.
- The polarization of the transmitting and receiving antennas should match to avoid signal loss.
- Directional antennas should be aligned precisely toward the receiver, as even small deviations reduce the gain.
- It is not recommended to mount antennas near sources of interference, such as microcontrollers or inverters.
- Chip antennas perform best when placed at the edge of the board, with open space around them.
How to verify antenna signal and whether it works properly?
Verifying antenna performance is an essential part of testing electronic devices, especially those that use wireless communication.
- In smartphones, routers or IoT gateways, you can use diagnostic applications or the device’s user interface to read the RSSI level. This helps assess the influence of antenna positioning.
- In prototype devices, the best tool is a vector network analyzer. It enables measurement of S11, resonant frequency, and bandwidth.
- An additional method is a field range test using a second device, which demonstrates the antenna’s performance in real conditions.
How to improve antenna signal strength?
- Using an antenna with higher gain is a simple way to improve system performance.
- Improving impedance matching, for example with an inductor or capacitor, can shift the resonance and reduce reflections.
- Using an external antenna and, for example, an SMA connector instead of a chip antenna can significantly improve efficiency.
- Changing the antenna’s position on the PCB or in the enclosure can greatly affect its performance by reducing losses caused by interference or proximity to conductive components.
- For stationary systems, consider using an amplifier.
How to connect an antenna to a device – what to consider?
- The key requirement is impedance matching between the antenna and the RF circuit.
- The coaxial cable should be kept as short as possible and properly shielded to minimize signal loss and reflections.
- The choice of RF connector (SMA, RP-SMA, u.FL) depends on the available space – it’s best to minimize the use of adapters.
- For PCB antennas, proper layout is essential. Make sure the impedance and ground design comply with the manufacturer’s requirements.
The most common mistakes when installing antennas – what to avoid?
- Placing an antenna in a metal housing without bringing it outside significantly degrades performance.
- Interference can also be caused by electronic components (e.g. microcontrollers, coils) placed too close.
- For chip antennas, it is crucial to maintain a metal-free zone.
- The antenna should be tested in the target environment.
- Changing its orientation can affect CE/FCC compliance so it’s worth planning for a tolerance margin.
Signal power starts with the design
Antennas are often underestimated, yet they play a crucial role in determining range, signal strength, and connection stability. Even the best transmitter won’t perform without proper matching, mounting, and thoughtful antenna placement. It’s important to consider antenna design as early as the PCB planning stage. At Device Prototype, we support projects where transmission quality is key. If you need assistance with antenna selection or integration – contact us.
