Antenna Chips
What is a chip antenna?
Chip antennas are a particular type of antenna valued for their small footprint. They are most commonly integrated into circuit boards to radiate high-frequency electromagnetic waves. They have a limited range, making them optimal for small devices such as cell phones and WiFi routers.
Handheld and portable wireless products such as smartphones and wearable electronic devices rely on microchips, patches, and PCB antennas that can be placed into the device.
While these small devices solve the problem of carrying multi-band antenna arrays in small form factor systems, they also introduce problems associated with reduced radiation efficiency, impedance matching, and interaction with nearby objects and the human body.
To address these issues, designers are beginning to adopt new design and circuit approaches that allow these antennas to become not just a standalone component, but part of a dynamic antenna subsystem capable of resolving many of these antenna design challenges. This antenna design shift requires extensive simulation and analysis, and the ever-improving field solver software can meet this need.
Antenna chips and patch antennas offer a compromise
There are many reasons for the transition from traditional external whip or short-cut antennas to chip and patch antennas, the first being the aesthetic and bendability issues associated with external antennas.
From a performance point of view, devices such as smartphones often require multiple antennas to provide antenna diversity in a given frequency band, thereby improving performance.
In addition, multi-band devices (especially those compatible with the emerging 5G standard) require separate stand-alone antennas for each band they must support. Despite all these reasons, chip antennas and patch antennas have their own shortcomings.
Chip antennas use a multi-layer ceramic structure to form components that resonate at the target frequency. As with all other surface mount components, they are small enough to be easily mounted on a PC board.
Many portable wireless devices would not be possible without small, low-cost, and easy-to-use ceramic chip antennas.
Chip antennas, despite their small size, provide a near-omnidirectional radiation pattern without regard to orientation. Antennas such as this have been used successfully in a wide range of portable and handheld wireless devices.
Although the chip antenna itself is simple, the designer must match the associated driver circuitry to its 50 Ω standard impedance. This can be a major problem when using multiple chip antennas in a diverse architecture.
Due to their low cost, small size, and ease of use, chip antennas appear to be the optimal solution for many wireless needs.
As with all components, chip antennas have their own shortcomings. In this case, their typical efficiency is relatively low at 40% to 50%, and they are susceptible to both fixed and changing conditions around them, including PC board layout, nearby components, and users.
An alternative to the chip antenna is the patch antenna. Although larger than the chip design, it is fairly flat and therefore can often be placed along the inside of the product enclosure, away from components and other sources of distortion of the radiation pattern.
The problem arises when a system contains multiple antennas and the topology requires switching between antennas, how to achieve the switching.
Electromechanical switching is effective and has excellent electrical specifications, but this is clearly impractical for small or portable devices and for devices that need to be switched on and off quickly.
Instead, electronic switches should be used, usually PIN diode-based switches or solid-state switches. Although the properties of a PIN diode are sometimes required, solid-state switches are easier to use and introduce into a circuit design than PIN diode-based switches.
Solving real-world problems with advanced technology
The performance of any antenna is influenced by its surroundings, including nearby components, shielding, and packaging. The effects of these elements can be modeled and taken into account in the final design, but this often requires multiple interactions to achieve a balance of conflicting requirements.
For compact portable and handheld devices, however, the problem is much more complex, as the antenna’s surroundings are constantly changing. Users may hold the product in different directions or close to different parts of the body (wrist, head, or torso) while using it, or place it near other objects.
As a result, the antenna is in a sub-optimal environment where the effective impedance and resonant frequency of the antenna can change and cause performance degradation.
When the resonant frequency of the antenna is shifted, the impedance it presents to the remainder of the radio front end also deviates from its initial value, resulting in an impedance mismatch.
The impedance mismatch has three effects. More energy is reflected back from the antenna terminals than passes through them; the output power from the power amplifier (PA) drops due to load traction, and the antenna’s radiation efficiency is reduced due to capacitive loading.
Modeling and simulation critical to chip antenna design success
For external antennas such as standard whip designs, there is little or no performance modeling early in the design cycle. But for chip antenna and PC board circuit printed antennas, and even for patch antennas very close to low noise amplifiers or power amplifiers, antenna simulation and its implementation are critical.
It is not possible to find the right configuration simply by building, testing, modifying, repeating, and iterating. Not only must the antenna be modeled, but also the entire surrounding environment (PC board, components, housing, and even the user’s hand or head position) must be modeled and analyzed.
Despite its simple function, the antenna is a complex electromagnetic sensor that converts electrical power in a circuit into an electromagnetic field and performs the inverse conversion.
Traditional single-piece antennas such as dipoles and whip antennas have now been enhanced with one or more antennas using multilayer ceramics, flat patch structures, or even the product’s own PC board.
Combining these antennas into a compact (often portable) product requires careful analysis of the entire system and package to verify that the idealized performance of the antenna is not unduly compromised and that the design objectives can be met.
C&T RF Antennas Inc is the antenna chips supplier in China, we provide large-scale antenna chips and other antenna types and chips, contact us for more details.