Feature: Wireless
Murata’s parasitic element coupling device
Parasitic element coupling device enables design of smaller,
high-performing antennas By Murata technical team
M
urata’s latest parasitic element coupling device is considered a state-of-the- art solution that improves antenna
efficiency by magnetically coupling the parasitic element with the antenna. It is also the world’s first solution suitable for Wi-Fi 6E and Wi-Fi 7 designs. For developers of smartphones, tablets,
network routers, game consoles and other compact electronics, this new Murata device allows them to build more efficient antennas – a key requirement for many modern, space- constrained devices. Even in high-speed Wi-Fi 6E- and
Wi-Fi 7-enabled systems, multiple high- performance antennas are required for better signal speed and quality. However, as the number of processors expands within these systems, so does the size of the heatsinks and batteries to support them, further reducing available space. Tis calls for much smaller antennas, with no degradation in signals. Te limitation here, however, is that the
efficiency of wideband antennas decreases as they are miniaturised. Tus, designers need a solution that achieves both miniaturisation and high performance. Using a parasitic element coupling device in the antenna block enlarges the bandwidth.
From parasitic to opportunistic Generally speaking, if a feeding antenna and a parasitic element are used together with a weak electromagnetic coupling, when the antenna size is smaller, the coupling between the parasitic element and ground will be stronger, weakening the coupling with the antenna. Tis reduces the functionality of the parasitic element as a radiating element and degrades the efficiency of the antenna. If the parasitic element is designed as a
coupling device, it can establish a strong electromagnetic coupling with the feeding antenna, improving antenna efficiency, even if the antenna’s size is small. Murata’s solution is a parasitic element
coupling device that uses a multilayer technology as a four-terminal surface- mount component, just 1.0 x 0.5 x 0.35mm large. Murata Manufacturing’s proprietary multilayer technology was used to place the transformer coil in close proximity, which achieves a strong electromagnetic field coupling, without needing a magnetic substance, largely deemed unsuitable for the targeted operating frequencies. Tis allowed these devices to contribute to better antenna characteristics and smaller sizes. Te device connects the feeding antenna
to its parasitic element more effectively than possible, through free space. One side of the coupling element is connected at very
60 July/August 2024
www.electronicsworld.co.uk
low insertion loss between the device’s RF circuitry and its main antenna, and the other side is connected between ground and the parasitic element. Tis results in more direct coupling, which enables the resonance characteristics of the parasitic element to be added to those of the feeding antenna, leading to more efficient operation across a broader frequency range or multiple discrete bands.
A long cable is no longer a problem Te feeding antenna can cause an impedance mismatch when used over a wide band, leading to a degradation in performance. In addition, when an antenna with a mismatched impedance is connected to a communication circuit with a long cable, the cable length can worsen the impedance mismatch, causing larger than expected insertion loss, thus significantly reducing the performance of the wireless communication. Since matching characteristics are improved, this prevents multipath reflection between the antenna and RF modules, and makes it possible to reduce the effects of insertion loss when using a long cable. Murata’s parasitic coupling device
allows better antenna matching and reduces performance degradation during communication – even when using long cables.
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