A Shape-Changeable Antenna Constructed by Distilled Water for Low-Profile and Low-Radar-Cross-Section Applications

A shape-changeable antenna constructed by an elastic container filled with distilled water is proposed. The antenna is modeled by a spherical dielectric resonator antenna, and the properties for the lowest resonant mode, and TM
₂₀₁
and TM
₃₀₁
modes are analyzed. The relationship between resonant frequency and diameter of the antenna is obtained, and the frequency reconfiguration is realized by injecting or pumping water into the elastic container. To verify the effectivity of the antenna, a prototype is fabricated and tested using an elastic balloon as an example. The measured results show that it is possible for the shape-changeable antenna to adjust the frequency continuously. The proposed antenna makes full use of the flexibility of water and exhibits features of changeable shape, simple structure, and high efficiency, which break the limitation of traditional water antennas with a fixed container structure. The design in this letter shows the possibility of constructing shape-changeable antennas by elastic materials, which provides an alternative approach to design low-profile and low- radar cross section antennas.