All About Flex: Flexible Circuit Antennas

Estimated reading time: 2 minutes

In our world of fabricating custom electronics, a circuit can generally be defined as “a path between two or more points along which an electrical current is carried.” The printed circuit board industry designs and fabricates an incredibly diverse set of rigid and flexible circuits. But it is also true this industry produces many parts that do not carry current between discreet points. 

A flexible “circuit” antenna is an example. Flexible circuits consist of a layer of flexible polymer film and a patterned conductive material (generally copper). The variety of polymer materials, and an infinite variety of sizes and copper patterns, allow unique designs across a wide range of frequencies. These custom shaped and uniquely patterned devices can also include components soldered to the copper, creating an electrical and mechanical interconnection between the component and the copper circuit trace.

An antenna functions to absorb electromagnetic waves and turn them into electrical pulses that replicate the pulses coming from the source. In the case of radio transmission, the sound from the source is converted to waves that propagate through space. The antenna receives these waves and the radio device turns the pulses into sound. Radio frequency (RF) is just one of many ranges of frequencies used in communication devices. 

Many electronic devices use wireless signals and thereby need antennas. Because these electronic devices have unique mechanical packaging constraints, the ideal antenna may need to conform to a variety of shapes, sizes and three dimensional configurations. Antennas from traditional flexible circuit materials can be configured into just about any shape and size. This utility has occasionally resulted in packaging engineers referring to flexible circuits as “origami interconnects.” It’s a good description as this formability makes them extremely versatile within space-constrained and tightly confined enclosures.  

Most antennas in electronic devices are connected to a PCB. Another advantage of a flexible circuit antenna is the antenna and the PCB can be fabricated as an integrated unit, reducing assembly costs while improving reliability. This enables a low cost and highly repeatable solution that offers advantages vs. other types of antennas.

By using PCB manufacturing techniques, highly reliable and repeatable antennas can be produced in high volume. The industry can fabricate, test and assemble antennas and accommodate quick turn production needs. Any communication- or signal-receiving device needs an antenna; the list below includes few of the more common applications:

• Bluetooth for hands-free phones
• GPS tracking, positioning and navigation devices
• Wireless local area networks for mobile hot-spots
• Cameras and gaming
• Signal reception for tablets and smart phones
• Wireless Internet TV and audio
• Telemedicine devices
• Cordless phones
• Personal digital assistants

Dave Becker is vice president of sales and marketing at All Flex Flexible Circuits LLC.