Microstrip Antennas for Remote Moisture Sensing using Passive RFID

• The paper presents how materials with a highability of absorbing moisture can be used with microstripantennas and passive RFID chips for constructing remotely readmoisture sensors. The concept is based on pairs of microstripantennas, applied on the same piece of PCB and each equippedwith one RFID chip, where one antenna is covered by themoisture absorbent material and the other is left open. In ahumid or wet environment the moisture concentration is higherin the absorbent material than in the surrounding environmentwhich causes degradation to the embedded antenna both interms of dielectric losses and change of input impedance. Thelevel of relative humidity or the amount of water in theabsorbent material is determined for a passive RFID system bycomparing the difference in RFID reader output power requiredto power up respectively the open and embedded tag. While ithas previously been shown how this can be accomplished withsimple one-layer antennas we here look into using microstripantennas to get around the problem with high influence frombackground material. Typical applications include moisturedetection in buildings, especially from leaking water pipeconnections hidden beyond walls or simply to measure the levelof relative humidity at hidden locations.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Annan elektroteknik och elektronik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Other Electrical Engineering, Electronic Engineering, Information Engineering (hsv//eng)

Keyword

RFID

Moisture Sensors

Antennas

Electronics

Elektronik

Publication and Content Type

ref (subject category)

kon (subject category)