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A single-layer microstrip patch unit element, which is loaded with eight concentric L-shaped slots, is proposed for reflectarray design. In this case, the lengths of the inner and outer slots are varied concurrently to function as the phase-shifting geometrical parameters. The reflection characteristics of the element are analyzed using the waveguide method, and the simulation results have been verified with experiments. A broad reflection phase range of 631.83° with slow gradient has been successfully achieved with the use of the slotted patch with constant size. Parametric analysis has been performed and it is found that the S-curve can be easily fine-tuned by changing some of the design parameters.

Two reader antennas, which are designed using the L-probe-fed suspended patch, are designed for the UHF band. To generate circular polarization, the L-shaped probe is modified by including an extra bend to provide one more degree of tuning freedom to the reflection coefficient without affecting the axial-ratio performance much. The proposed single-element reader antenna is able to achieve a CP bandwidth of 5.5 % (890 MHz - 940 MHz) and a maximum antenna gain of 9.7 dBi. When designed into a 2x2 array, the proposed reader antenna is able to produce CP bandwidth of 5.3 % (910 MHz - 960 MHz) with an antenna gain of 14.7 dBi. The read ranges of the proposed antenna and its array are 6.3 m and 10.9 m, respectively.

A fiber taper acoustic sensor utilize the ability of taper structure to modulate vibration signal into the fiber transmission power. Currently, there is a lack of detailed study on the bending effect of fiber taper to the fiber transmission power. In this paper, wide-angle propagation method is used to simulate the effect of fiber taper bending. The reconstructed time-domain signal and time-domain signal modulated from vibration has a nonlinear negative relationship and has a correlation coefficient value of 0.9979.

In this paper, a low-cost portable microwave reflectometer is designed and developed to measure glucose content in aqueous solution. The proposed microwave measurement system is constructed by using microwave circuit with a non-invasive open-ended coaxial probe sensor. Reflection method is used due to its simplicity and suitability of detecting the glucose concentration. The reflected microwave signal is detected by coaxial probe sensor and converted into voltage signal using power detector. Empirical models between the reflection coefficient and the glucose concentration from 10% to 60% have been developed. The reflectometer measurements are compared with Vector Network Analyser, and validated using different batch of samples. The proposed reflectometer demonstrates reasonable accuracy with an error of less than 4.5%.

A linearly polarized single-layer single-resonator reflectarray, which is designed using a simple circular patch loaded with two unequal rectangular slots, is investigated for the first time. For the proposed design, the linearity and sensitivity of the phase curve (S-curve) can be easily optimized by adjusting the ratio of the two unequal slots changeable according to a simple design equation. Here, the patch radius serves as a phase-shifting geometrical parameter and it is able to achieve a wide phase range of more than 458° with low phase sensitivity and a low reflection loss of less than 0.5 dB. With the use of the optimized phase curve, an offset-fed 13 × 13 full-fledged reflectarray with a square aperture is designed, fabricated and measured. Measurement results show that a −1-dB gain bandwidth of 11.8% and an antenna gain of 23.4 dBi are realizable at the center frequency of 9.3 GHz. Also, the proposed reflectarray has an aperture efficiency of 42% and a radiation efficiency of 98%. The proposed reflectarray has a simple structure and it is able to achieve smooth phase curve, low cross-polarized radiation field and low sidelobes.

This paper presents an ultra-wideband (UWB) and off-optimised Five-Port Reflectometer (FPR) configured by power splitters. The proposed non-multi-state FPR is characterised and realised for complex reflection coefficient determinations. The measurement system can be easily setup using commercial power splitters, three detectors and a microwave source. The transmission lines method is used as calibration standard for FPR measurement system. Both the FPR setup and the transmission lines are characterised with a Vector Network Analyser prior to be used for the off-optimised measurement system. The results show good agreement between actual and calculated reflection coefficient for frequency range of 0.1 to 40 GHz. This novel FPR setup provides a simple, cost effective and accurate alternative in measuring broadband complex reflection coefficient.

A new reflectarray is designed using two co-joined L-shaped probes. In this case, the horizontal lengths of the two L-shaped probes are functioning as the phase-shifters. The unit element is simulated using the Floquet cell, and simulation shows that the unit element is able to provide a linear phase range of 454.2°. A full-fledge reflectarray consisting of 121 elements is designed, fabricated, and measured. The proposed reflectarray is able to achieve an antenna gain of 20.43dBi and a −1dB gain bandwidth of 15.38%.