Low-Profile and Electrically Small Meander-Line Antenna Using a Capacitive Feed Structure

An electrically small and low-profile meander-line antenna using a capacitive feed structure is presented. The meander line has a length of one quarter-wavelength with a shorted end, and the capacitive feed structure is installed at the other end. A back conductor, which works as a ground plane, is located at a distance of 0.01λ
₀
to the meander-line element forming in the area of 0.121λ
₀
× 0.075λ
₀
, which satisfies the condition of electrically small antennas (ka = 0.435 <; 0.5, wavenumber k, radius a of a sphere surrounding the antenna, and wavelength λ
₀
at the resonance frequency). The fabricated antenna has successfully achieved a peak gain of 0.62 dBi and exhibits a higher radiation efficiency of more than 30% compared to an inverted-F antenna of the same dimension.