Parasitic Element Coupling Device enables improved antenna design

2 mins read

Murata has developed a new Parasitic Element Coupling Device that improves antenna efficiency by magnetically coupling the parasitic element with the antenna.

This is said to be the world's first solution designed for Wi-Fi 6E and Wi-Fi 7 products and for designers of smartphones, tablets, network routers, game consoles, and other compact electronics, it enables them to build more efficient antennas – a key requirement for many modern space-constrained devices.

To develop products conforming to Wi-Fi 6E and Wi-Fi 7 standards, which utilise high-speed wireless communication, multiple high-performance antennas must be installed in electronic devices to improve communication speed and quality. However, as the dimensions of heatsinks and batteries expand, and as processors become more advanced, so the available space for mounting antennas decreases.

Consequently, there is a need for smaller antennas. But there is a technical limitation, in that the efficiency of wide-band antennas decreases when they are miniaturised – so designers need a solution that achieves both miniaturisation and high performance.

Murata’s parasitic element coupling device, made with its multilayer technology, is a four-terminal surface-mount component measuring just 1.0 x 0.5 x 0.35mm.

The device connects the feeding antenna to its parasitic elements more effectively than is possible through free space. It acts as a tiny coupling device whose compact size enables strong coupling performance without the use of magnetic materials, which would be inappropriate at the targeted operating frequencies.

One side of the coupling device is connected, at very low insertion loss, between a device’s RF circuitry and its main antenna. The other side is connected between the ground and the parasitic element. This results in more direct coupling which enables the resonance characteristics of the parasitic element to be added to those of the feeding antenna. As a result, it enables more efficient operation across a broader frequency range or on multiple discrete bands.

The device helps to combat that when an antenna is made smaller, the coupling between it and the parasitic elements is reduced, while the coupling between the parasitic elements and the ground is increased. By sustaining the coupling between the feeding antenna and parasitic element, the parasitic element coupling device enables designers to use miniaturised antenna design methods without impacting the communication band of efficiency.

The feeding antenna can cause an impedance mismatch when used over a wide band, leading to a degradation in wireless performance. In addition, when an antenna with a mismatched impedance is connected to a communication circuit using a long cable, the long cable can promote the impedance mismatch, causing a larger insertion loss than expected and significantly reducing wireless communication performance.

According to Murata, by using this device, designers can improve antenna matching and reduce performance degradation in wireless communications even when using long cables.