Design of wideband Rotman lens for wireless applications

An electrically steerable beam is an essential standard in the recent wireless application in order to increase the gain and reduce the interference. However, high performance of amplitude besides low phase error difficult to achieve without indicators are used to set lens parameters to desired optimum performance design level. In this paper, the introduced microstrip lens has examined a comprehensive explanation for parameters and indications amid a full wave structure methodology. Further, Phase and energy coupling between excited ports and received ports besides phase error and its relation with the lens parameters design are explained in detailed.  A wideband beamforming network based on a printed microstrip Rotman lens with a ±26o scanning angle was designed in this study. The designed lens operates at 2.45 GHz with 592 MHz bandwidth. The lens consists of five switchable ports (input ports) with four output ports that connected to the microstrip patch antennas. The five switchable ports were used to realize the scanning beams angle in the azimuth plane.  The proposed model is simulated by CST Microwave Studio and fabricated on FR-4 with 1.565 mm thickness and 4.2 permittivity.  A good agreement between simulation and measurement results were achieved

Dual-wavelength thulium fluoride fiber laser based on SMF-TMSIF-SMF interferometer as potential source for microwave generationin 100-GHz region

A dual-wavelength thulium-doped fluoride fiber (TDFF) laser is presented. The generation of the TDFF laser is achieved with the incorporation of a single modemultimode- single mode (SMS) interferometer in the laser cavity. The simple SMS interferometer is fabricated using the combination of two-mode step index fiber and single-mode fiber. With this proposed design, as many as eight stable laser lines are experimentally demonstrated. Moreover, when a tunable bandpass filter is inserted in the laser cavity, a dual-wavelength TDFF laser can be achieved in a 1.5-μm region. By heterodyning the dual-wavelength laser, simulation results suggest that the generated microwave signals can be tuned from 105.678 to 106.524 GHz with a constant step of �0.14 GHz. The presented photonics-based microwave generation method could provide alternative solution for 5G signal sources in 100-GHz region

Assessment of Electromagnetic Absorption towards Human Head Using Specific Absorption Rate

This paper presents a compact square slot patch antenna characterstics for wireless body area network (WBANs) applications.The assessment of the effects of electromagnetic energy (EM) on the human head is necessary because the sensitivity of human head to high radiation level. Although, structuring of low EM antennas is a major problem in the improvement of portable device and reducing the size of of the antenna is a major concern. However, performance of antenna reduces when antenna operates near human body which is lossy and complex in nature. The proposed antenna operates at 5.8GHz of the ISM Band for WBAN applications. The antenna has been designed and simulated with two different types of multilayer human head phantoms to characterize the antenna near the human head.The multilayer head phantom is constructed by five layers tissues head model using CST Microwave studio. Therefore, antenna with spherical phantom has the highest SAR value 0.206 W/Kg, while antenna with cubical phantom contributed the lowest SAR value of 0.166 for 10 g tissue at 5.8 GHz frequency exposed, whereas, the antenna with cubical phantom and spherical phantom have gain of 6.46 dBi and 6.2 dBi GHz respectively. It was observed that antenna performance significantly increased. The presented prototype has a potential to work for ISM applications

Design and implementation of microstrip rotman lens for ISM band applications

This work presents the design and implementation of Rotman lens as a beam steering device for Industrial, Scientific, and Medical (ISM) applications. 2.45 GHz is considered as a center frequency design with (2-6) GHz frequency bandwidth. The beam steering is examined to cover ±21o scan angle with maximum main lobe magnitude 10.1 dBi, rectangular patch antennas are used as radiation elements to beam the output far field. The work is extended to compare between the tapered line which is used for matching between 50-Ω ports and lens cavity. CST microwave simulation studio results show that the rectangular taper line can yield 2 dB return loss less than linear taper line with a little bit shifting in responses for same input and load impedance

Switchable 10, 20, and 30 GHz region photonics-based microwave generation using thulium-doped fluoride fiber laser

In this work, switchable 10, 20, and 30 GHz region photonics-based microwave generation in a fiber laser cavity is proposed and demonstrated. The microwave generation is based on the beating of a dual-wavelength thuliumdoped fluoride fiber laser. With the aid of a micro-air gap in an adapter, single, double, and triple Brillouin spacing can be generated in a single fiber laser cavity without re-routing the cavity. The wavelength spacing of the dual wavelengths that are induced by the single, double, and triple Brillouin spacing are 0.084, 0.166, and 0.254 nm, respectively, at a center wavelength of 1490 nm. In addition, a numerical calculation is performed using MATLAB to prove the generation of microwave signals at 11.34, 22.44, and 34.3 GHz. With the advantage of switchability among the 10, 20, and 30 GHz regions, the proposed photonics-based microwave generation is promising for the advancement of 5G technologies

A Microwave Signal Generation Technique Based on Brillouin-Erbium Fiber Laser

An all-optical microwave signal generator based on multiwavelength Brillouin-Erbium fiber laser (MBEFL) is proposed. The MBEFL unit is designed at fixed wavelength spacing of 0.084 nm, which corresponds to ~10 GHz carrier signal. The underlying mechanism MBEFL unit is by recycling the backscattered Stokes waves into the cavity to generate higher-order Stokes waves. Heterodyning process is then applied to the Brillouin pump (BP) consisted of first-order Brillouin Stokes (BS1) (0.084 nm spacing) and second-order Brillouin Stokes (BS2) (0.168 nm spacing) signals by using a photodetector (PD). The heterodyned outputs are microwave signals at the frequencies of 10.56 GHz and 21.2 GHz, relative to first order and second order Stokes waves, respectively. These microwave signals are experimentally achieved by controlling the EDF pump power where the EDF pump power can be as low as 20 mW

Dual-wavelength thulium fluoride fiber laser based on SMF-TMSIF-SMF interferometer as potential source for microwave generation in 100-g hz region

A dual-wavelength thulium-doped fluoride fiber (TDFF) laser is presented. The generation of the TDFF laser is achieved with the incorporation of a single modemultimode-single mode (SMS) interferometer in the laser cavity. The simple SMS interferometer is fabricated using the combination of two-mode step index fiber and single-mode fiber. With this proposed design, as many as eight stable laser lines are experimentally demonstrated. Moreover, when a tunable bandpass filter is inserted in the laser cavity, a dual-wavelength TDFF laser can be achieved in a 1.5-µm region. By heterodyning the dual-wavelength laser, simulation results suggest that the generated microwave signals can be tuned from 105.678 to 106.524 GHz with a constant step of ∼0.14 GHz. The presented photonics-based microwave generation method could provide alternative solution for 5G signal sources in 100-GHz region

Novel Spiral With and Without Patch EBG Structures for EMI Reduction

Electromagnetic bandgap structures (EBGs) have the ability to provide excellent reduction of electromagnetic interference (EMI). In this work, a 3 by 3 spiral with and without patch electromagnetic bandgap planar was fabricated on low cost FR4 substrate with permittivity of 4.3 and thickness of 1.6mm. Both designs have dimensions of 36 mm x 36 mm covering 9 unit cells planar design. The simulation and experimental characteristics are illustrated in this paper. An acceptable agreement between the simulated and measured results was obtained. It was found that the spiral without patch EBG experienced better bandgap than the spiral with patch design, which covered bandgap of (5.8 – 7.4 GHz) with relative bandwidth of 22.56%. Meanwhile, for the spiral with patch structure, it covered C band (4.5 – 7 GHz) with extended relative bandwidth of 43%. The results of the characteristics demonstrate that the proposed EBGs are attractive candidates for the integration into the high speed circuitry designs where spiral with patch can be involved in C band applications to suppress the EMI emitted by their circuitry

Development of Ground Penetrating Radar Hybrid System Using Vivaldi Antenna for Buried Object Detection

Ground penetrating radar (GPR) is categorized based on the number of antenna and modulation technique used for buried object detection. GPR systems that were often studied are the GPR of amplitude modulation and GPR of frequency modulation. Based on these two types of GPR system, the GPR of frequency modulation which is known as Stepped Frequency Continuous Wave (SFCW) is easy to be developed using only antenna and vector network analyzer (VNA). This study combined the Pulse modulation and SFCW GPR to form the GPR Hybrid. The combination was made in order to develop Pulse modulation GPR system of amplitude modulation GPR type using VNA. Discussion on this developed Hybrid GPR using the CST studio Suite 2014 software, included the design of a GPR antenna called the Vivaldi antenna of patch types, the design on simulation system of GPR Hybrid system, and the implementation of GPR Hybrid system using vector network analyzer. After the validation process, the developed GPR Hybrid system equipment was able to successfully detect a metal object that was buried in a wooden chamber containing dry sand