Qiang Bai

Crumpling of PIFA Textile Antenna

The performance of a PIFA textile antenna under different crumpling conditions is presented. The PIFA was designed for integration into clothing and other textile applications and the bending and crumpling conditions studied are typical of those found under normal use conditions both on and off body. Input impedance, efficiency and radiation patterns are investigated based on numerical and experimental methods at 2.4 GHz. Crumpling can have a serious effect on the resonant frequency, bandwidth and radiation from textile antennas.

Wearable EBG antenna bending and crumpling

In this paper, we present the performance of a dual-band textile CPW antenna under different bending and crumpling conditions. The performance of the antenna is presented together with an electromagnetic band gap material (EBG) to improve the wearable antenna performance. The input impedance and radiation pattern are investigated based on numerical and experimental methods at 2.45 GHz and 5.8 GHz.

Generation of orbital angular momentum (OAM) radio beams with phased patch array

This paper describes the design of an 8-element circular phased patch array antenna which can generate radio beams carrying orbital angular momentum at 10 GHz. Realistic antenna design issues are discussed, including mutual coupling and the array performance when operating in different OAM states.

Crumpling of Microstrip Antenna Array

The performance of a 2 × 2 microstrip patch array under crumpling conditions is presented. The antenna array was manufactured on textile material, and three cases of crumpling resembling real applications are discussed. The performance of the individual patch elements correlate with the overall performance of the array. Frequency shifts of up to 6% are measured for the array when crumpled, the boresight gain is reduced by up to 6 dB with significant changes in directivity and efficiency, up to 20%. The overall efficiency for the textile array increases for crumpling in one plane but falls in the other.

Generation and detection of OAM signals for radio communications

Orbital angular momentum radio has great potential for radio communications that require high security, spectrum efficiency and a large data rate. However, the performance of such a system, measured in terms of mode errors, is highly dependent on the alignment between the centre of the receiver array and the transmit array boresight. In addition, other impairment phenomena, such as transmit array imperfections, receiver phase errors and thermal noise can considerably degrade the performance of the orbital angular momentum radio system. In this paper, the effects caused by receive array angular and phase errors are evaluated by means of simulations. Furthermore, Monte Carlo simulations are employed to obtain the bit error rate performance of multi-level modulation orbital angular momentum radio systems.

Textile PIFA antenna bending

This paper presents the performance of a textile PIFA antenna under several bending and crumpling conditions. Input impedance, efficiency and radiation patterns are investigated based on numerical and experimental methods at 2.4 GHz.

Fabrication of a 3D electrically small antenna using holographic photolithography

We describe the novel fabrication of a 3D electrical small antenna and its subsequent characterization. The patterning of meander lines conformed onto a hemispherical substrate is achieved by 3D holographic photolithography, which uses time-division multiplexing of a series of iteratively optimized computer-generated holograms. The meander lines have a line width of 100 µm and line separation of 400 µm, with a line pitch of 500 µm and a total meander length of 145 mm. The working frequency is found to be 2.06 GHz, with an efficiency of 46%. This work demonstrates a new method for the fabrication of 3D conformal antennas.

An experimental phased array for OAM generation

This paper presents an experimental 8-element circular phased patch array antenna which can generate radio beams carrying mode -1 orbital angular momentum. A microstrip feeding network is used to excite the radiation elements. Both input impedance and radiation patterns are investigated based on numerical and experimental methods.

Demonstration of RF Digitising Concurrent Dual-Band Receiver for Carrier Aggregation over TV White Spaces

In order to meet the high data rate, low latency and high energy efficiency requirements, the future radio units must utilise the frequency spectrum available at certain geographical location efficiently with a minimum amount of hardware. This requires frequency agility and concurrent multi-standard operation capabilities at the base and mobile terminals. To utilise the TV white spaces for mobile and wireless communication and enable their carrier aggregation with sub GHz LTE bands, this paper presents a single-chain, reconfigurable, RF digitising, dual- band receiver comprised of a tunable dual-band antenna, a reconfigurable digital down converter, a baseband processing unit and wideband LNA and ADC in the form of an oscilloscope. The presented dual-band receiver is tested through a hardware- in-the-loop test-bed which shows that up to 20 MHz aggregate bandwidths can be achieved. The receiver is able to provide equivalent error vector magnitude (EVM) performance across a wide range of frequencies avoiding any inter-band interference.

Switchable Electromagnetic Bandgap Surface Wave Antenna

This paper presents a novel switchable electromagnetic bandgap surface wave antenna that can support both a surface wave and normal mode radiation for communications at 2.45 GHz. In the surface wave mode, the antenna has a monopole-like radiation pattern with a measured gain of 4.4 dBi at ±49° and a null on boresight. In the normal mode, the antenna operates like a back-fed microstrip patch antenna.