Over the Air Measurement Techniques for Time Varying Electrically Small Antennas

open_access
Open Access
Author:
Hall, Owen
Area of Honors:
Computer Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Gregory Huff, Thesis Supervisor
John Morgan Sampson, Thesis Honors Advisor
Keywords:
Electrically small antennas
ESA
Chu-Harrington limit
capacitance modulation
bandwidth enhancement
efficiency
time-varying capacitance
over-the-air testing
Error Vector Magnitude
EVM
Bit Error Rate
BER
Modulation Error Ratio
MER
signal analysis
impedance matching
harmonic generation
RF circuits
antenna performance
nonlinearity
resonant frequency
Q-factor
wireless communication
adaptive tuning
circuit optimization
system losses
electromagnetic compatibility
RF measurements
testing methodology
antenna miniaturization
real-time signal processing
Electrically Small Antennas
Chu-Harrington Limit
Capacitance Modulation
Bandwidth
Time-varying Capacitance
Over-the-air testing
Impedance Matching
RF Circuits
Antenna Performance
Testing
Antenna Miniaturization
Simulation
Antenna Testing
Abstract:
Antennas are fundamental to modern wireless communication, playing a critical role in applications ranging from aerospace systems to portable devices. However, electrically small antennas (ESAs) are inherently constrained by the Chu-Harrington limit, which imposes trade offs between size, bandwidth, and efficiency. This thesis investigates the potential of time varying capacitance in ESAs to enhance bandwidth and overall performance beyond these traditional limitations. Through an over-the-air testing setup, this work evaluates the impact of capacitance modulation on key performance metrics, including Error Vector Magnitude (EVM), Bit Error Rate (BER), and Modulation Error Ratio (MER). Most significantly, an original testing methodology is introduced, incorporating real-time signal analysis to quantify performance improvements over conventional ESA designs. Experimental results demonstrate that while capacitance modulation introduces measurable variations in signal fidelity, practical implementation challenges such as component non-idealities and system losses hinder clear performance gains. These findings suggest that while time-varying capacitance remains a promising approach, additional refinements in circuit design and testing conditions are necessary to fully unlock its potential. This work provides a foundation for future studies by outlining key technical barriers and proposing paths for further optimization in ESA development.