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This paper presents the design of a compact circular microstrip patch antenna for WLAN applications which covers the band 5.15 to 5.825 GHz. The antenna is designed using 1.4mm thick FR-4 (lossy)substrate with relative permittivity 4.4 and a microstrip line feed is used. The radius of the circular patch is chosen as 7.62mm. To reduce the size and enhance the performance of the proposed antenna, a circular slot is loaded on circular patch and a square slot is etched on the ground plane of dimension 30mm×30mm. Design of the antenna is carried out using CST Microsoft Studio Sonimulation Software. The proposed antenna resonates at 5.5 GHz with a wider bandwidth of 702 MHz and it provides low return loss of -31.58 dB, good gain of 3.23 dB and directivity of 4.28 dBi and high efficiency of around 79% against the resonance frequency. The geometry of the proposed circular antenna with reduced size and its various performance parameters such as return loss, bandwidth, VSWR, gain, directivity, efficiency and radiation pattern plots are presented and discussed

Digital modulation increases information capacity, data security, and system availability while maintaining high communication quality. As a result, digital modulation techniques are in higher demand than analog modulation techniques due to their ability to transmit larger amounts of data. Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK), Differential Phase Shift Keying (DPSK), and Quadrature Amplitude Modulation (QAM) are critical components of current communications systems development, particularly for broadband wireless communications. In this paper, the comparison of bit error rate performance of different modulation schemes (BPSK, QPSK, and16-QAM) and various equalization techniques such as constant modulus algorithm (CMA) and maximum likelihood sequence estimate (MLSE) for the AWGN and Rayleigh fading channels is analyzed using Simulink. BPSK outperforms QPSK and 16-QAM when compared to the other two digital modulation schemes. Among the three digital modulation schemes, BPSK is showing better performance as compared to QPSK and 16-QAM.

Wireless communications are among the rapidly growing fields in our current life and have a massive effect on every aspect of our everyday life. In this paper, the performance of the various digital modulation techniques (BPSK, DPSK, QPSK, and QAM) based wireless communication system on the audio signal transmission through the additive Gaussian Noise (AWGN) channel is assessed on the basis of bit error rate (BER) as a function of the signal-to-noise ratio (SNR). Based on the results of this study, BPSK modulation outperforms the DPSK, QPSK, and QAM modulation strategies in the MIMO MC-CDMA VBlast based wireless communication system. The digital modulation of QPSK shows the worst performance in audio signal transmission especially in comparison to other digital modulations. It is clear from the current simulation study based on MATLAB that the V-Blast encoded 4×4 MIMO MC-CDMA wireless system with minimum mean square error (MMSE) signal detection and 1⁄2-rated convolution and cyclic redundancy check (CRC) channel encoding strategies show good performance utilizing BPSK digital modulation in audio signal transmission.

This paper presents the development of a sensor based smart irrigation system with the capabilities of remote monitoring and controlling of water usage in the agriculture field using Internet of Things (IoT). With the employment of IoT in irrigation system, all agricultural information can be viewed and controlled at the user's fingertips. The system consists of a microcontroller (Node MCU), sensors (soil moisture, DHT11), and irrigation of a water pump with a decision-making system. Sensors are linked to a Wi-Fi module (Node MCU) and are interdependent to provide increased sensitivity to the irrigation system. The data obtained will be uploaded to the cloud (ThingSpeak) and presented in the form of graphs accessible via the website. A web page is used to control the water pump for irrigation purposes. This paper is managed to meet all of its aims to help farmers in terms of time, project cost, labor, water consumption, power consumption, and reliability by implementing the IoT-based smart irrigation system.

The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM) schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN channel and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2- rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission.

In this paper, the impact of patch and ground plane slots on the bandwidth performance of a microstrip UWB antenna is presented. Our reference antenna is a microstrip feeding type monopole feature with a rectangular patch and a partial ground plane. In order to evaluate the characteristics of the reference antenna bandwidth, two separate slot types (right-angle triangular and rectangular) have been inserted into the patch and a single slot configuration like a rectangular is also inserted into the partial ground plane on the backside of the feed line to the appropriate. The influence on the bandwidth characteristics of single and multiple slot cases is analyzed using the HFSS simulator. Based on the slot configurations, the simulation results verify that the antenna bandwidth can be improved.

We have developed an optical method of detecting and characterizing nonradiative recombination (NRR) centers without electrical contact. The method combines a below-gap excitation (BGE) light with a conventional above-gap excitation light in photoluminescence (PL) measurement, and discriminates the PL intensity change due to switching on and off the BGE. A quantitative analysis of the detected NRR centers became possible by utilizing the saturating tendency of the PL intensity change with increasing the BGE density due to trap filling effect. Some experimental results of AlGaAs, InGaN, and AlGaN quantum wells were shown to allocate the development and present status as well as to exemplify their interpretations.