Imaging Spatially Varying Dielectric Samples Using Tightly Coupled Dipole Array Based Near-Field Sensing

Area of Science:

• Electromagnetics and Microwave Engineering
• Sensor Technology
• Materials Science

Background:

• Near-field microwave sensing is crucial for non-invasive material characterization.
• Traditional Vector Network Analyzer (VNA) systems can be complex and costly.
• Developing simplified, high-sensitivity microwave sensors is an ongoing research area.

Purpose of the Study:

• To present a novel microwave sensing platform for near-field dielectric contrast mapping.
• To demonstrate a low-complexity, robust alternative to VNA-based measurements.
• To validate the sensor's capability in mapping electromagnetic property variations.

Main Methods:

• Design and fabrication of an 8x8 tightly coupled dipole array (TCDA) operating at 830 MHz.
• Utilized a 32-way equal power divider for uniform aperture excitation.
• Employed rectified DC voltage shifts to detect changes in dielectric properties.

Main Results:

• The dipole array achieved high absorption (>90%), enhancing near-field intensity.
• Successfully mapped spatial variations in dielectric samples, saline solutions, and biological tissues.
• Demonstrated capability to detect dielectric property changes (ϵr≈ 70-78).

Conclusions:

• The proposed 32-element dipole array sensor provides a proof-of-concept for effective dielectric contrast mapping.
• This architecture simplifies RF routing and eliminates the need for multi-port switches, offering a cost-effective solution.
• The sensor shows promise for applications requiring non-invasive characterization of electromagnetic properties.