How Origami-Inspired Phased Arrays are Reshaping the Future of Antennas
Folding antennas into different shapes to create near infinite radiation patterns.
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To freshen things up a bit, I decided to look up latest research from the 2024 International Microwave Symposium, the premier conference in the field of RF and Microwave engineering. What I found was an idea so interesting that I felt compelled to write about it.
As it turns out, there is a new class of RF circuits that draw inspiration from Origami, the Japanese1 art of paper folding. Just like you can make different shapes out of paper, you can physically reconfigure circuits to operate differently.
Hani Al Jamal, a PhD student, and a team of researchers led by Prof. Manos Tentzeris at Georgia Tech, authored a paper titled Beyond Planar: An Additively Manufactured, Origami-Inspired Shape-Changing, and RFIC-Based Phased Array for Near-Limitless Radiation Pattern Reconfigurability in 5G/mm-Wave Applications, which won the Best Paper Award at the 2024 International Microwave Symposium.
This paper describes a phased array antenna from which you can synthesize any radiation pattern. It uses both electronic and physical modifications to achieve this.
Special thanks to Hani for providing additional information, pictures and for reviewing a draft of this post.
In this post, we will get into the details of exactly how this works.
Need for Adaptive RF Circuits
Eggbox Phased Array
Interconnect Systems
Practical Applications
Need for Adaptive RF Circuits
Fixed RF systems are not optimum for changing RF environments. It is preferable if RF blocks are context aware and adjust to give optimal overall system performance. Previously, reconfigurability meant that components such as antennas were mounted on large servos and moved about to point to the source of the signal. In fact, radio astronomers continue to build big parabolic dishes on train tracks and move them about to make various configurations in order to receive faint signals from space. This is often too slow for modern applications.
Engineers soon realized that they could achieve the same outcomes by steering antennas with phased arrays. Instead of shifting the antennas, they could achieve the same result by adjusting the phase shift between separate antennas. The constructive and destructive interference between the array's antennas helped to steer the radiated beam without physically moving it. Because everything is electronic, steering antennas takes only a few microseconds.
If you need an introduction to antenna and phased arrays, check out my earlier posts.
What if we could combine physical alteration and electronic beam steering? This is an excellent use for foldable phased arrays, as it allows for slow, origami-like physical transformations, followed by quick directional changes via electronic beam steering. Can we create any antenna pattern we desire and then direct the beam?
Eggbox Phased Array
The phased array antenna in the Georgia Tech research paper was inspired by the design of an eggbox made of paper. It's just a grid of upside-down square-base pyramids with an open base for eggs. The research study describes how one of these open-base pyramids might be utilized as a foundation for bigger reconfigurable arrays. When looking at just one of them, the unit cell resembles an origami fortune teller, which my children frequently build.
A 4-element phased array antenna is installed on all four faces of this eggbox-unit/fortune-teller, and the beam is steered in 11.25° increments by a Qorvo AWMF-0108 28 GHz beamformer RFIC.
This unit cell, like an origami design, may be folded across either axis or laid flat, allowing you to physically change the direction of radiation. Because the phased array antenna on each face can steer the beam further, the antenna can be utilized to generate almost any radiation pattern using a combination of physical folding and electronic beam steering.
Here are some ways to shape the radiated beam from this antenna.
360° azimuth coverage: In its pyramidal arrangement, activate only one phased array and direct the beam to its maximum value before switching to the phased array on the next face. This ensures a continuous handoff between multiple phased arrays on the faces while also providing 360° azimuth beam steering.
Bending along an axis: Fold the array along any one axis, and as the fold angle reduces the radiation pattern changes from a four-beam to a two-beam configuration, as illustrated in the image.
Arbitrary shaped beams: Fold the array by an arbitrary angle across either axis, turn on anywhere from a single phased array to all four phased arrays, apply digital weights to the phased array to control both amplitude and phase to antenna elements (even gain tapering to control grating lobes), and you can virtually synthesize any radiation pattern you are looking for.
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https://www.viksnewsletter.com/p/origami-inspired-phased-arrays....
Beyond Planar: An Additively Manufactured, Origami-Inspired Shape-Changing, and RFIC-Based Phased Array for Near-Limitless Radiation Pattern Reconfigurability in 5G/mm-Wave Applications
https://ieeexplore.ieee.org/abstract/document/10531260This letter presents an origami-inspired phased array operating at 28 GHz, with on-structure beamformer RFICs and a flexible feeding network that utilizes a foldable hinge interconnect. The mm-wave origami phased array therein operates at a substantially smaller scale compared with prior literature and achieves remarkable integration with on-structure beamforming circuitry. It introduces the first additively manufactured fully foldable hinge interconnect, exhibiting near-constant insertion loss across various folding angles and cycles. Leveraging origami principles, the phased array offers near 360° continuous beam steering in the azimuth plane with reconfigurable multibeam or quasi-isotropic radiation patterns. Additive manufacturing techniques, including 3-D and inkjet printing, are used to fabricate a low-cost and lightweight prototype. Measurements demonstrating near-limitless pattern reconfigurability due to mechanical shape change and electrical beam steering signify a significant leap in overcoming challenges faced by traditional phased arrays.
Published in: IEEE Microwave and Wireless Technology Letters ( Volume: 34, Issue: 6, June 2024)
Page(s): 841 - 844
Date of Publication: 16 May 2024
ISSN Information:
DOI: 10.1109/LMWT.2024.3396026