Future wireless networks, including the sixth generation (i.e., 6G) cellular communications networks, require high-speed and high-capacity information transfer with high reliability and low latency. Meanwhile, electronic steering and highly directive radiation afforded by phased antenna array apertures stand to enable wide implementation of future 5G/6G infrastructure. To this end, CEARL researchers are actively developing advanced ground-breaking 5G/6G EM  devices by exploiting our custom modeling and optimization tools while collaborating with world experts in semiconductor fabrication. We hope to address the challenges facing future communications networks by developing new and disruptive technologies which we anticipate will be of significant interest to the antennas and EM communities at large as well as those in the commercial, defense, and intelligence sectors

Body area networks (BANS), sometimes also referred to as body sensor networks or body-centric networks, are wireless communication networks of wearable devices that transmit information within, on, near, or around the human body. In these systems, distributed wearable and/or implanted sensors are required to communicate with either other on-body computing devices such as smart phones, watches or glasses, or more distant off-body systems like wireless routers. CEARL researchers develop highly performant wearable antennas for next generation BANs and on/off-body communications.

In recent years there has been an increased demand for communication systems with wideband and multifrequency capabilities. Antenna arrays, representing an important component of many communication systems, must be able to keep up with these latest demands. A vast majority of array designs are still based on the conventional periodic element distribution. This type of array has its benefits but it is inherently limited in terms of bandwidth due to the presence of grating lobes at element spacings of one-wavelength or greater. Among the various ways to extend the bandwidth of these arrays are design techniques that involve utilizing non-periodic, or aperiodic, configurations. Our research has shown that judicious selection of the aperiodic configuration can lead to designs with bandwidths much larger than their conventional periodic counterparts. 

Polyfractal arrays and perturbed aperiodic tiling arrays have recently emerged as categories of arrays that can lead to designs with ultrawideband performance. Bandwidths (SLL < -10 dB and no grating lobes) of up to 40:1 have been reported for polyfractal arrays while bandwidths of up to 22:1 have been reported for perturbed aperiodic tiling arrays.

The term fractal was originally coined by Benoit Mandelbrot in 1975 and the concept was born out of a search for order in the disorder of life (biology, economics, physics, etc.). Fractals have found wide-spread practical application in many fields of mathematics, physics, and engineering. Members of CEARL are actively involved in developing new designs for antenna elements as well as array configurations that exploit properties of fractals. We call this relatively new and innovative area of research Fractal Antenna Engineering. 

Since the pioneering work of Heinrich Hertz, perfect-electric conductor (PEC) loop antennas for RF applications have been studied extensively. Meanwhile, nanoloops are promising in the optical regime for their applications in a wide range of emerging technologies. Unfortunately, analytical expressions for the radiation properties of conducting loops have not been extended to the optical regime. CEARL researchers have developed closed form analytical solutions to the radiation properties of nanoloop antennas valid from radio to optical frequencies. These analytical solutions have enabled us to discover previously undemonstrated properties of nanoloop antennas including superdirectivity.

Additive manufacturing (3D printing) allows for cheap and fast prototyping of antennas with complex geometries that would otherwise be impractical to fabricate. To take advantage of this technology, a new shape generation method has been developed which utilizes freeform 3D meanderlines with arbitrary cross sections. The increased design space offered by this method means that antennas created using this technique can have unique and useful properties. Some examples include a multiband monopole for use in Wi-Fi applications, a dual band helical antenna with unique radiation properties in each band, and a wideband quadrifilar helix with over 100% fractional bandwidth (pictured). Antennas can be printed using a 3D printer and then metallized using either conductive paint or electroplating.

Wireless power transfer has been a dream since Nikola Tesla and CEARL researchers are investigating ways to usher in a new era for wireless power transfer. Techniques such as parity-time (PT) symmetry recently has been exploited to enable dynamic wireless power transfer in non-Hermitian systems with high efficiency. Additionally, hybridizing novel antennas with specialized metamaterials show promise to usher in the next generation wireless power transfer systems.

CEARL researchers developed an Advanced Short Backfire Antenna (A-SBFA), augmented with anisotropic metamaterial surfaces (metasurfaces) to achieve a very high aperture efficiency across two frequency bands. This performance is unprecedented for an antenna that has seen widespread use, but few design changes over its more than 50 year existence. The reduced weight, compact design, hexagonal aperture, high dual-band efficiency, high cross-polarization isolation, as well as low multipaction and passive intermodulation (PIM) risk make the A-SBFA ideal for spaceborne applications and is being considered as an option for future GPS systems. 

Lens antennas can be used to increase the directivity of existing antenna systems in order to improve system performance. Furthermore, lens antennas can be used to significantly reduce system SWaP (size, weight, and power) compared to conventional antenna solutions. CEARL researchers use techniques including adjoint optimization, transformation optics, and our own custom shape optimization techniques to design unintuitive metamaterial and gradient-index (GRIN) lenses which achieve custom design goals. In addition to performing all of the computational modeling and optimization, we use our 3D printers to fabricate lenses and measure them in-house, enabling a rapid prototyping design cycle.