Position sensing of liquid metal antennas for beam scanning antenna arrays

-March 17, 2014

Presenting the 1st prize winner in the TI LDC1000 inductive sensor design contest.

High gain beam scanning arrays are usually implemented using phased antenna arrays or mechanically controlled parabolic dishes. However, the aforementioned technologies are widely known as costly ones. Recently, a new design of beam scanning arrays has been introduced using the liquid metal technology. Specifically, the antenna is made of a liquid metal volume that is encapsulated in channels and moved mechanically using a single mechanical pump.

To implement this technology successfully, the liquid metal antenna should be exactly located in the a reservoir with minimum physical misalignment. Therefore, it is essential to sense the antenna location with respect to the desired reservoir. Moreover, the sensing system should be cost effective and simple, yet accurate and highly sensitive. Having that mentioned, the LDC1000 sounds as a potential candidate to develop a position sensing system for the proposed antenna array.

Specifically, The LDC1000 can be utilized to carry out the sensing operation by designing and constructing a feedback system. By using the LDC1000, an inductance vs. misalignment design curve can be designed to determine and sense the antenna position and send feedback commands to the pump in order to adjust and move the antenna. If successful, this proposed solution will significantly contribute in implementing low cost beam scanning arrays. In addition, the solution can be extended to modify the LDC1000 design to allow sensing different positions at the same time using only one LDC1000 piece.

In order to test the possibility of using the LDC1000 in detecting the antenna in a microfluidic channel, a prototype microfluidic channel with an antenna encapsulated in it was first fabricated. Later, the LDC1000 inductance was measured using the GUI software when the inductive sensor was located on the top of an empty reservoir location and the inductance was recorded. Next, the sensor was moved to a reservoir where the antenna was located and the sensor inductance change was monitored. Specifically, the sensor inductance dropped as the sensor overlapped with the antenna.

As a result, the inductive sensor can be utilized for detecting the antenna location, and thus, the beam direction by scanning the sensor among the channel and noticing the senor inductance reduction. Scanning the senor can be performed using a step motor and the whole system can be programmed using a compact micro-controller with low cost and very sensitive monitoring.

Other Sensing Design Challenge 2013 winners:

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