In this study, a novel dual‐band multiple‐input multiple‐output (MIMO) rectangular dielectric resonator antenna (DRA) for Worldwide interoperability for microwave access (WiMAX) (3.4–3.7) GHz and wireless local area network (WLAN) (5.15–5.35) GHz applications is proposed and investigated. The design operates at fundamental TEδ11x, TE1δ1y and higher order TEδ21x, TE2δ1y modes, excited through two coaxial probes, symmetrically placed adjacent to the DRA. A compact design is achieved by stacking a high permittivity material. The obtained impedance bandwidth at 3.6 GHz is 9.97% and at 5.2 GHz is 8.88%. Measured antenna gain through both ports at 3.6 GHz is 5.7 dBi and at 5.2 GHz is 6.61 dBi, respectively. Isolation achieved at 3.6 GHz is −13 dB and at 5.2 GHz is −16 dB, respectively. Co‐ and cross‐polarisation, radiation efficiency, diversity gain, envelope correlation and mean effective gain of the proposed design are measured. Results show that the proposed design is suitable for use in MIMO WiMAX/WLAN applications.
Human activity monitoring is an exciting research area to assist independent living among disabled and elderly population. Various techniques have been proposed to recognise human activities, such as exploiting sensors, cameras, wearables, and contactless microwave sensing. Among these, the microwave sensing has recently gained significant attention due to its merit to solve the privacy concerns of cameras and discomfort caused by wearables. However, the existing microwave sensing techniques have a basic disadvantage of requiring controlled and ideal settings for high-accuracy activity detections, which restricts its wide adoptions in non-line-of-sight (Non-LOS) environments. Here, we propose a concept of intelligent wireless walls (IWW) to ensure high-precision activity monitoring in complex environments wherein the conventional microwave sensing is invalid. The IWW is composed of a reconfigurable intelligent surface (RIS) that can perform beam steering and beamforming, and machine learning algorithms that can automatically detect the human activities with high accuracy. Two complex environments are considered: one is a corridor junction scenario with transmitter and receiver in separate corridor sections and the other is a multi-floor scenario wherein the transmitter and receiver are placed on two different floors of a building. In each of the aforementioned environments, three distinct body movements are considered namely, sitting, standing, and walking. Two subjects, one male and one female perform these activities in both environments. It is demonstrated that IWW provide a maximum detection gain of 28% in multi-floor scenario and 25% in corridor junction scenario as compared to traditional microwave sensing without RIS.
This study presents work carried out on a multiband‐dielectric resonator antenna (M‐DRA) for long‐term evolution (LTE) application. A new stack M‐DRA is introduced by using two dielectric resonators of different permittivities, stacked on top of each other. The M‐DRA is excited using a coaxial probe. The introduction of a finite planar conducting wall reduces the overall size of the proposed M‐DRA. It operates at LTE band‐VI (828–880 MHz), GSM 1800/1900 and UMTS 2100 for S11<−10 dB. The measurements performed with a fabricated antenna showed good agreement with the simulated results.
A compact UWB monopole band-notched antenna with simple structure and small size is proposed and studied in this article. The size of the antenna is 33 3 29.6 3 1.6 mm. The proposed antenna has an impedance bandwidth (VSWR < 2) at 3.1-10 GHz, except the bandwidth at 3.3-3.7 GHz and 5.15-5.82 GHz for WLAN and WiMAX application. A notch in the ground plane is used to obtain a frequency band-notched response at 3.3-3.7 GHz and inverted U-shaped slot in the radiator patch is used for the rejection of frequency band 5. 15-5.82 GHz. The antenna prototype is fabricated and tested, and it is observed that the measured and simulated results are in good agreement.
This paper presents a multi-bit reconfigurable intelligent surface (RIS) with a high phase resolution, capable of beam-steering in the azimuthal plane at sub-6 Gigahertz (GHz). Field trials in realistic indoor deployments have been carried out, with coverage enhancement performance ascertained for three common wireless communication scenarios. Namely, serving users in an open lobby with mixed line of sight and nonline of sight conditions, communication via a junction between long corridors, and a multi-floor scenario with propagation via windows. This work explores the potential for reconfigurable intelligent surface (RIS) deployment to mitigate non-line of sight effects in indoor wireless communications. In a single transmitter, single receiver non-line of sight link, received power improvement of as much as 40 dB is shown to be achievable by suitable placement of a RIS, with an instantaneous bandwidth of at least 100 MHz possible over a 3 to 4.5 GHz range. In addition, the effects of phase resolution on the optimal power reception for the multi-bit RIS have been experimentally verified, with a 2.65 dB improvement compared to a 1-bit case.
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