Researchers have created a printing process that can print on curved, irregular surfaces with nanoink. The resulting antenna enjoys almost perfect reception.  (Source: University of Illinois)

Postdoctoral researcher Jacob Adams designed the unique printing process with principle investigators Jennifer Bernhard and Jennifer Lewis.  (Source: University of Illinois)
"Can you hear me now?"

It's happened to all of us.  You're in the middle of an intense conversation, and your cell phone cuts out.  Even today, in the era of 4G and smartphones, it's still difficult to completely avoid the most basic failure of a cell phone -- a dropped call.

Enterprising researchers at the University of Illinois have devised an antenna that uses a revolutionary 100 µm micro-nozzle silver nanoink printing process to print an antenna on a 3D substrate to try to remedy that problem [press release].

As a demo, they printed nanoink on the outside or exterior of a hollow hemisphere of glass.  This wasn't easy to do.  States Jennifer T. Bernhard [profile], the computer and electrical engineering professor leading the project, "Unlike planar substrates, the surface normal is constantly changing on curvilinear surfaces, which presents added fabrication challenges. To our knowledge, this is the first demonstration of 3D printed antennas on curvilinear surfaces."

Current phone antennas perform relatively poorly, because many are shorter than their operating wavelength. And some are poorer than others (like the first hardware version iPhone 4).  Designing a 3D antenna has been the goal of several research projects.  Describes Professor Bernhard, "Recent attention has been directed toward producing antennas by screen-printing, inkjet printing, and liquid metal-filled microfluidics in simple motifs, such as dipoles and loops."

But she feels that her design is the best attempt at creating a 3D antenna yet.  She states, "Omnidirectional printing of metallic nanoparticle inks offers an attractive alternative for meeting the demanding form factors of 3D electrically small antennas (ESAs)."

She says that the antenna they printed and tested was near "perfect" from a reception perspective.  She writes, "There has been a long-standing problem of minimizing the ratio of energy stored to energy radiated—the Q—of an ESA. By printing directly on the hemispherical substrate, we have a highly versatile single-mode antenna with a Q that very closely approaches the fundamental limit dictated by physics (known as the Chu limit)."

By adjusting the space of the meandering lines and the total antenna cross section, the 3D antenna design can be tuned to a particular operating frequency.

The antenna design could have many applications, as the ink can be printed on a variety of substrates and surfaces -- not just hollow hemispheres.  States Professor Bernhard, "This conformal printing technique can be extended other potential applications, including flexible, implantable, and wearable antennas, electronics, and sensors."

Antennas could potentially be printed on the inside of cell phone cases, inside the cases of laptops, or on the wings of military unmanned aerial vehicles (UAVs) -- offering long desired super-low Q antennas for these applications.

A paper on the work, entitled "Conformal Printing of Electrically Small Antennas on Three-Dimensional Surfaces" [abstract] has been published in the March 18 edition of the peer-reviewed journal of materials.  

If the antenna is everything that is claimed, hopefully mass production of the printing process can be worked out, as the material required -- silver nanoink -- is relatively cheap and available.  If the printing nozzle/equipment can be pushed out at an affordable cost, your smart phone in a couple years could get a 3D antenna and better reception. 

Of course this will only help to eliminate the number of problems on the phone side.  Cell phone networks can have uncovered patches and cell phone towers can be overloaded in cases of high use.  Having a fancy antenna will most definitely not help you with those kinds of problems.

"This is from the It's a science website." -- Rush Limbaugh

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