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When ethanol and water are mixed into gasoline, the dielectric properties of gasoline will change. Based on this characteristic, we propose an antenna sensor and study its radiation and sensing performance in detection of ethanol gasoline in 6-7GHz band. In order to avoid the corrosion of the oil sample on the antenna, the antenna adopts a multilayer dielectric substrate structure. A $2\times 2$ artificial magnetic conductor (AMC) array is loaded on the bottom of the antenna to increase the gain of the sensor and reduce the return loss. The antenna sensor has good radiation pattern with a peak gain of 4 dB and high quality factor(Q) up to 69. Furthermore, the antenna sensor shows the advantages of high sensitivity and wide detection range on the detection of oil-water mixture and ethanol gasoline concentration. In order to verify the simulated results, the radiation and sensing performance of the antenna were measured, and the measured results were basically consistent with the simulated ones. Therefore, the proposed antenna sensor can be used for real-time wireless detection in ethanol gasoline transportation.

Pathological changes of human tissues, such as tumors, can cause changes in the dielectric properties of the tissues. Based on this characteristic, we propose an implantable antenna sensor and study its radiation and sensing performance in breast tumor recurrence diagnosis in the 2.45 GHz Industrial, Scientific, and Medical (ISM) band. The antenna sensor shows the advantage of miniaturization with a volume of 13.2mm3 by employing an S-shape monopole antenna and a closed loop. The simulated results show that the antenna sensor has a good radiation pattern with peak gain values of −8.4 and −17.9dBi in normal and malignant breast tissue, respectively. Furthermore, the antenna sensor exhibits good sensitivity to the dielectric properties of breast tissue. When the permittivity increases by 10, the resonance frequency decreases between 9-18MHz. To verify the simulated results, the sensing properties and the radiation patterns of the implantable antenna sensor were measured in the pork and tissue-mimicking liquid. The measured results are consistent with the simulated ones. Hence, the proposed antenna can be used as a wireless sensor to monitor pathological changes of human tissues, such as breast tumors.

In this paper, a wearable antenna pressure sensor with electromagnetic bandgap (EBG) is proposed, which can be used to monitor the walking and fall states of the elderly. When the elderly walks and falls suddenly, the knee or elbow wearing the antenna sensor will touch the ground and put a lot of pressure on the antenna sensor, resulting in the resonance frequency shifts. The proposed antenna sensor is fabricated on flexible silicone substrate and works in the 2.45 GHz industrial, scientific and medical (ISM) band. A 3 × 3 EBG array is designed to reduce the specific absorption rate (SAR) of the antenna to the human body and increase the forward peak gain of the antenna from 1.63dBi to 4.36dBi. Furthermore, the antenna sensor exhibits high sensitivity of about 11 MHz/N to the pressure. To verify the simulated results, the sensing properties of the wearable antenna sensor were measured. The measured results have been found to be consistent with the simulated ones. Moreover, the bending performance study and SAR analysis reveal that the proposed antenna sensor is a good candidate for wearable devices.