Research

Relevant publications:

VHF & UHF Energy Harvesting Radio System Physical and MAC Layer Considerations
Xiaohu Zhang, Kansas State University, 2009

Energy Harvesting

By using the energy emitted by the sun, it should be possible to create a communication device that can be remotely solar-powered.  This was the idea behind the Energy Harvesting project pursued by former graduate student Xiaohu Zhang.

To supply the energy needed to power and drive the device, solar cells used in common, handheld calculators were implemented on the device.  Simple tests verified the operation of these cells.

The project resulted in the production of a solar-powered communication demoboard, pictured below.  The communication IC, which is responsible for the transmission of RF signals, was designed by Ph.D. students and professors at KSU.

 

Device Testing

It was necessary to confirm that the testboard was indeed communicating properly.  So, using test equipment rated to Microwave frequencies, the performance of the device was substantiated.  The media below document parts of this process.

Preparing the Test Environment

 

The "dummy data" seen on this oscilloscope  is the result of preparing the test environment.   The video above is this audible signal.

The gray signal pictured here  represents the 60-bit initialization  sequence needed to program  the PIC used on the testboard.  The green signal is the RFIC  on the board, responding to the  input stimuli.

 

Characterizing the Performance

The images below summarize the performance of the testboard.

This plot shows the calculated transmit  power vs. the distance away from the  receiver, at 2.4 GHz.

This image compares the  different ranges and  corresponding transmit  powers for differing frequencies  of operation as measured from  the testboard.