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Water antennas are a special type of antennas and have attracted limited attention so far. In this study, a monopole water antenna with a dielectric layer is chosen as an example to study some less obvious characteristics of the water antenna. The resonant frequency, radiation efficiency and fractional bandwidth are of particular interest. Firstly, the effects of the dielectric layer between the water and the ground plane are studied. The results show that this layer has a crucial effect on the antenna resonant frequency and radiation efficiency. Secondly, the water with different conductivity is investigated. With different conductivity, the antenna may be regarded as a dielectric resonant antenna, a conducting antenna or their combination. Thirdly, a water antenna with a supporting structure is fabricated for validation. Measurements are conducted in an anechoic chamber and a reverberation chamber to evaluate its performance as a function of various parameters. Finally, the water temperature electromagnetic characteristics are investigated. Good agreements are achieved between the simulation and measurement results. It is shown that this type of antenna shows better performance than the conventional antenna in aspects such as broadband, cost, reconfigurability, transparency and it can be a promising candidate for a range of applications.

A flexible meandered loop antenna is proposed, designed and realised for small cylindrical implantable devices. This antenna covers the Medical Device Radiocommunications Service (MedRadio) and the 433-434 MHz industrial, scientific and medical (ISM) bands, and is probably the smallest reported flexible implantable antenna that covers these bands. This antenna has shown a robust performance in the presence of implant internal components and has a realised gain of − 28.4 dBi inside a model of a human upper arm.

A compact ultra-wideband planar monopole antenna with a size of 22 mm by 34 mm is presented to achieve the quintuple-band-notched characteristics. The proposed antenna consists of a Mickey-mouse shaped radiating element, a truncated/smoothed ground plane and a microstrip feed-line. The quintuple-band-notched function is achieved by integrating five specially designed half/one-wavelength M-shaped resonators into the radiator, feed-line and ground plane. The simulated and measured results show that the proposed antenna is able to operate from 2.24 to 10.8 GHz for |S11| < −10 dB with excellent band rejection performance in the frequency bands of 2.35 to 2.61 GHz, 3.16 to 3.69 GHz, 5.0 to 6.1 GHz, 7.2 to 7.7 GHz and 8.1 to 8.74 GHz for some existing communication systems such as wireless local area networks, worldwide interoperability for microwave access, downlink of X-band satellite communication and ITU 8-GHz band, respectively. In addition, both the frequency-domain and time-domain performances of the antenna are investigated by simulation and measurement. The results obtained are also in very good agreement.

In this paper a flexible loop antenna is proposed for biomedical bone implants in the Medical Device Radiocommunications Service (401-406 MHz) and the Industrial Scientific and Medical (433-434.8 MHz) bands which is probably the first bone implantable antenna that covers these bands. This antenna has shown a robust performance against up to 50 % of the variations of the body dielectric properties. The main design considerations for bone implantable antennas in comparison with the corresponding considerations for muscle implantable antennas are also addressed in this paper. Index Terms-Biomedical telemetry, bone implants, flexible antenna, Industrial Sceientific and Medical (ISM) antenna , Medical Device Radiocommunications Service (MedRadio) antenna.