Optically Controlled Bias-Free Frequency Reconfigurable Antenna

Area of Science:

• Antenna Engineering
• Metamaterials and Reconfigurable Antennas
• Wireless Communication Systems

Background:

• Conventional antenna tuning relies on DC biasing networks, introducing parasitic effects, losses, and complexity.
• Energy-constrained platforms like IoT devices require simplified, low-power antenna solutions.
• Existing tuning methods often involve bulky components and significant power consumption.

Purpose of the Study:

• To present a bias-free antenna tuning technique that eliminates conventional DC biasing networks.
• To demonstrate the use of a Light-Dependent Resistor (LDR) for optical control of antenna resonance.
• To validate the proposed technique on a compact, reconfigurable antenna for IoT applications.

Main Methods:

• Integration of a Light-Dependent Resistor (LDR) into the antenna structure for optical modulation.
• Optical illumination used to alter the LDR's resistance, thereby tuning the antenna's electrical length.
• Fabrication and testing of a prototype ring monopole antenna with an embedded LDR.

Main Results:

• The LDR-based antenna achieved tunable tri-band operation through optical control of resistance states.
• In the high-resistance state, the antenna operated across 2.1-3.1 GHz, 3.5-4 GHz, and 5-7 GHz.
• In the low-resistance state, the lowest band shifted to 1.36-2.35 GHz, with gains up to 5.3 dBi and maintained linear polarization.

Conclusions:

• The proposed bias-free antenna tuning technique effectively eliminates conventional biasing networks using an LDR and optical control.
• The design offers a compact, low-cost, and energy-efficient solution suitable for portable wireless devices and IoT nodes.
• This approach minimizes parasitic effects and routing complexity, paving the way for practical reconfigurable antennas in resource-limited systems.