This paper presents the design and analysis of a new compact quad-band metamaterial absorber (MMA). The proposed structure is constructed as an array of 12x13 unit cells, each one is based on a combination of interlaced I/square resonators supporting four distinct resonant frequencies. The proposed metamaterial unit cell is printed on FR-4 substrate with thickness 1.5 mm and size 20 mm × 20 mm. The MMA structure exhibits four distinct absorption peaks at 2.248, 2.878, 4.3 and 5.872 GHz with absorption rates of 96, 93, 93, and 95 %, respectively, under normal incidence. This design achieves a negative permittivity and permeability that is applicable for S-band and C-band operating frequencies. The MMA unit cell structure has a 3-dB bandwidth of 78, 89, 144 and 202.6 MHz. The proposed structure has compactness of 0.15 λ0 × 0.15 λ0 with thickness of 0.0112 λ0, where λ0 is the free-space wavelength with respect to the lowest resonance frequency (2.248 GHz). The input impedance, surface currents and electric field distributions are shown to illustrate the mechanism of the structure. The design has been fabricated showing a good agreement between simulated and measured results. The proposed absorber structure can be used in different applications such as electro-magnetic protections, as well as military and medical applications. All simulation results are performed using the Computer Simulation Technology (CST), Microwave Studio 2018 software and Mathwork simulation tool MATLAB ver. 2011.

In this paper, a new dual band metamaterial absorber based on sun fractal structure is presented. The proposed metamaterial absorber unit cell is printed on FR-4 substrate with thickness 1.6 mm and it has compact size 37×37 mm ² . The proposed metamaterial absorber structure exhibits two distinct absorption peaks at 2.24 and 7 GHz with peak absorption values of 97.2 and 98 % respectively. All simulation results are performed using the Computer Simulation Technology (CST) Microwave Studio 2018 software.

Accurate water consumption measurement and equitable billing are vital for sustainable water resource management, especially in regions facing scarcity and uneven distribution. Conventional systems, which often rely on shared mechanical meters, fail to provide individual usage data, leading to disputes, waste, and inefficiencies. This paper presents the design and experimental validation of a low-cost, IoT-enabled Smart Water Billing System (SWBS) that delivers real-time consumption monitoring, adaptive calibration, and automated proportional billing. The proposed system integrates an ESP8266 NodeMCU, YF-B1 Hall-effect flow sensors, and anomaly detection algorithms to ensure precise measurement and early leak detection, where the IoT functionality of the prototype is realized through the Wi-Fi-enabled NodeMCU, which transmits processed consumption and status data to a remote backend using HTTP-based communication for cloud-connected logging and monitoring. A multi-stage calibration method was developed to maintain accuracy across diverse flow rates, reducing measurement error to below 3%. Experimental results confirm that the system reliably tracks individual unit consumption, supports scalable deployment in multi-unit buildings, and provides transparent billing through wireless data transmission. By combining affordability, accuracy, and real-time analytics, the SWBS offers a sustainable solution for modern urban water management, promoting conservation and fair resource distribution.