A novel combination of loop and dipole antennas into a Yagi-like structure is here investigated to implement a wearable antenna. The textile antenna is designed for being integrated into a smart glove together with a compact UHF-RFID reader. A number of compact Yagi-like textile structures have been analysed and compared, which consist of a rhombus-shaped folded dipole and parasitic elements acting as either a reflector or directors. The latter are needed to focus the field out of the operator hand, so limiting the radiation toward undesired directions. Four compact Yagi-like layouts (with one or two directors, with one director and one reflector, and with one reflector and two directors) are developed on a stretchable fabric and their performance is measured in terms of reflection coefficient and near-field distribution. Reading range performance is measured by using COTS RFID reader and tags.

A novel reconfigurable microstrip-fed patch antenna with polarization agility in either of two bands is proposed in this communication. Frequency reconfigurability is achieved by connecting an additional small patch to the main patch through a p-i-n diode. Each corner is cutoff from the main patch through a narrow L-shaped cut to get polarization reconfigurability. In addition, the impedance and axial ratio bandwidths are enhanced by using the proximity-coupled feed. Both prototypes are designed, fabricated, and tested. The measured results agree well with the simulated results in all cases. Also, the proposed microstrip-fed antenna is tested at high RF input power. The proposed structures are simple, low profile, low cost, and have simple bias circuitry. The proposed antennas are capable of operating in three polarization states, i.e., left-hand circular polarization, linear polarization, and right-hand circular polarization in two frequency bands. The proposed structures are best suited for modern advanced wireless communication systems such as LTE and 5G.

In this paper, a polarization switchable reconfigurable microstrip patch antenna is designed first, it is extended further to get polarization switching in three switchable frequency bands by using corner connection/disconnection and additional patch connection/disconnection techniques. Three switchable operating bands are obtained with centre frequencies of 5.1 GHz (first band), 5.45 GHz (second band), and 6.3 GHz (third band) using 5 p-i-n diodes. Proposed structure is capable of being switched between left-hand circular polarization (LHCP), right-hand circular polarization (RHCP), and linear polarization (LP) in all three switchable frequency bands. A proximity coupled triangular tapered feed is used to feed the structure to get wide impedance and axial ratio bandwidths. Detailed analysis is carried out to observe the effects of various design parameters on the performance of the circuit. This also gives insight into the behavior of the circuit in terms of resonance frequency which would be useful to translate the structure at different frequency bands for various applications. Measured performance of the antenna agrees well with the simulations. The prototyped antenna has an acceptable reflection coefficient and axial ratio (AR below 3dB) in each operating band. Polarization and frequency diversities of the proposed design could enhance the reliability of modern wireless systems.

A compact wearable dual-band quasi-Yagi RFID-reader antenna is designed for being incorporated into a smart glove. The antenna dual-band capability allows the integration of both the RFID reader at UHF band and a wireless data link at 2.4GHz, into a single compact and wearable device. Dipole and loop antennas are combined into a quasi-Yagi structure to be placed on a hand back, in order to detect tagged objects close to the hand palm and fingers, during the operator normal activities. The dual-band driven element consists of a rectangular-shaped folded dipole (resonating at the ETSI UHF RFID band, 865-868 MHz) and a rhombus-shaped folded dipole (resonating at the WLAN band, 2400-2485 MHz). A few parasitic elements (reflector and directors) are included to focus the field in the required direction, namely out of the worker’s hand. A prototype of the proposed textile antenna is developed on a stretchable fabric and its performance is measured in terms of read range and near-field distribution, at 868 MHz, and radiation pattern and gain at 2.45 GHz.

A wideband, low-profile, 3D automotive antenna for Long-Term Evolution (LTE) and 5G applications is presented in this paper. Different from other cellular antennas typically placed under the shark-fin cover or inside a car’s plastic spoiler, the proposed antenna is designed to be integrated inside the vehicle’s dashboard. The 35.5 × 40 × 45 mm³ antenna is compact, lightweight and robust. At the same time, this antenna is capable of operating from 670 up to 5000 MHz, covering the entire LTE/5G band (overall fractional bandwidth of 198%). A shunt stub was introduced between the monopole and ground plane to achieve a low LTE band and provide mechanical robustness for the proposed structure. Simulated performance in terms of reflection coefficient, radiation pattern and realized gain is described, showing a good agreement with the measurement results. Specifically, the antenna has a gain higher than −1 dBi at the low-frequency band (i.e., below 1 GHz) and higher than 3 dBi at the upper-frequency band (i.e., above 1.7 GHz). As per requirements, the ground plane size and layout can be properly chosen to fit the antenna into the available volume as well as to optimize the antenna’s performance.

A reconfigurable microstrip patch antenna with switchable polarization is proposed in this paper. The proposed antenna consists of a nearly square patch as a radiator truncated at two corners, two small parasitic patches are connected at the corners by using PIN diodes. The impedance bandwidth and axial ratio bandwidth are enhanced by changing the shape of the truncated corners. Good impedance match (S11 < −10 dB) and axial ratio (AR < 3 dB) are achieved at the operating frequency (5.15 GHz). The measured results are well matched with the simulated results and validated the switching operation of the antenna in three polarization states, i.e. left-hand circular polarization, linear polarization, and right-hand circular polarization. The proposed antenna is also tested at high RF power and measured its performance. The proposed antennas are suitable for WI-FI and WLAN applications.