In this study, the effect of loading microstrip antenna using epsilon near zero (ENZ) metamaterial is investigated. It is known that ENZ material may help to improve the transmission through a boundary condition and that the scattering parameters may be completely independent of such boundary properties. This idea is demonstrated to significantly increase the bandwidth of a simple rectangular microstrip patch antenna. To realise the ENZ material, a periodic wire medium is designed, simulated, fabricated, and tested. Simulation results based on CST Microwave studio have good agreement with measurements.
Backscatter networks (such as RFID, and WiFi backscatter) are very attractive for IoT applications due to their ultra-low energy consumption. In fact, their required energy to operate is low enough that it can be harvested from the environment without having a battery. However, existing backscatter networks offer very limited data-rates (i.e. at most one Mbps). Hence, despite their energy benefit, their applications are very limited. This paper presents the design of mmTag, a backscatter network which can achieve Gbps data-rates. mmTag achieves this by developing a backscatter technology operating in the mmWave spectrum band. mmWave promises to enable high throughput wireless links by offering massive chunks of high-frequency spectrum. However, to use mmWave frequencies in backscatter networks, we need to address a fundamental challenge: beam alignment. mmWave devices require highly directional antennas with very narrow beams, and communication is possible only when the transmitter's beam is aligned with the receiver's beam. However, existing beam searching techniques require power hungry components, and most importantly require the node to transmit a signal which is not possible for a backscatter device. mmTag solves this problem by building a mmWave backscatter tag which performs beam alignment without using any active component. Finally, we implement mmTag and empirically demonstrate some results.
With the advent of the Internet of Things (IoT), billions of new connected devices will come online, placing a huge strain on today's Wi-Fi and cellular spectrum. This problem will be further exacerbated by the fact that many of these IoT devices are low-power devices that use low-rate modulation schemes and therefore do not use the spectrum efficiently. Millimeter wave (mmWave) technology promises to revolutionize wireless networks and solve the spectrum shortage problem through the usage of massive chunks of high-frequency spectrum. However, existing mmWave networks are power-hungry and expensive, which make them unsuitable for low-power, low-cost IoT devices. In this paper, we present mmX, a system which significantly reduces cost and power consumption of a mmWave network, enabling its use in IoT applications.
In this article, the capability of epsilon‐near‐zero (ENZ) metamaterial (MTM) to reduce mutual coupling between densely packed array elements is examined. The results show a reduction in mutual coupling between antenna elements and provide a possible way to reduce the element separation. To verify and confirm the simulation results, a prototype of the proposed ENZ structure incorporating an array of closely implemented patch antennas, 0.12λ
L, are fabricated and tested. The array antenna has an overall dimension of approximately 2.66λ
L × 1.75λ
L × 0.05λ
L while achieving an average gain and efficiency of 7 dB and 85%, respectively. Measurement shows that the mutual coupling is mostly better than −20 dB across a broad bandwidth of >2.6:1 (10.5–27.7 GHz).
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