A new design of photonic transmitter for terahertz spectroscopy and imaging applications

In this paper we present the Design of Continuous Wave Terahertz photonic transmitter based on photodetector, THz antenna, and low-pass filter (LPF) and Direct Current “DC” Probe Bias. Before validating the whole system, we processed firstly with the optimization of the antenna which is responsible of the transmitting the RF signal providing from the photodetector then we have conducted a study on the design of a low pass filter “LPF” whose role is to block the received RF signal to reach the DC probe. After the optimisation of the proposed LPF, we have integrated the different components mounted on multi-layers GaAs substrate and simulated the final photonic transmitter by using an EM solver “Momentum” integrated in ADS “Advanced Design System”. The dimensions of the whole circuit are  .The simulation results permit to validate the final circuit at 1.6 THz, the proposed photonic transmitter is suitable for terahertz spectroscopy and imaging applications

A novel design of circularly polarized pentagonal planar antenna for ISM band applications

This paper presents a new circular polarized micro-strip antenna with a pentagonal shape radiator. The proposed antenna is designed to operate in the industrial scientific medical (ISM) band at the frequency of 2.45GHz for Wireless applications. The antenna consists of a radiating pentagon patch with appropriate dimensions on the upper side of a dielectric substrate and a defective ground structure (DGS) on the other side. The pentagon patch is fed through a 50Ω microstrip line. The structure is implemented on an FR-4 substrate with a relative permittivity of 4.4, loss tangent equal to 0.025 and thickness 1.58 mm. The antenna is designed and simulated by using advanced design system (ADS) electromagnetic solver and the achieved results are validated by using another electromagnetic solver. The simulation results indicate that the designed circularly polarized (CP) pentagonal microstrip patch antenna gives good results in terms of the reflection coefficient, voltage standing wave ratio (VSWR) and, axial ratio of 1.025 at 2.45 GHz

Bandwidth enhancement of compact microstrip rectangular antennas for UWB applications

In this paper design of microstrip patch antennas are presented for ultra wideband (UWB) applications. The designed antennas have good matching input impedance in a wide frequency band covering the UWB frequency band which is defined by the FCC. The proposed antennas consist of rectangular patch which is fed by 50Ω microstrip line. These antennas are investigated and optimized by using CST microwave studio, they are validated by using another electromagnetic solver HFSS. The proposed antennas are designed and optimized taking into account the optimized of the ground by using Defected Ground Structure (DGS) in order to improve the frequency band of microstrip antenna. Hence, the impedance and surface current of the antenna structures are affected by DGS. As will be seen, the operation bandwidth of the proposed antennas is from 3 to 15 GHz (return loss≤-10 dB), corresponding to wide input impedance bandwidth (133.33%), with stable omnidirectional radiation patterns and important gain. A good agreement has been obtained between simulation and measurement results in term of bandwidth clearly show the validity of the proposed structures. These antennas are useful for UWB applications, may be able to potentially minimize frequency interference from many wireless technologies i.e WLAN, WiMAX. Details of the antennas have been investigated numerically and experimentally

A New Planar Multiband Antenna for GPS, ISM and WiMAX Applications

In this paper a design of a new antenna with modified ground plane is validated for multiband applications. The proposed modified ground structure is incorporated with a patch antenna to boost the performance. The antenna’s entire area is 59.5x47mm2 and is printed on an FR-4 substrate and fed by a 50 Ohm microstrip line.  This structure is validated in the GPS (1.56-1.58 GHz) band at 1.57 GHz, in the ISM (2.43-2.49 GHz) band at 2.45GHz and in the WiMAX (3.50-3.56 GHz) band at 3.53 GHz. These three frequency bands have good matching input impedance for, S11≤-10 dB. The antenna presents a good performance in terms of radiation pattern, and it is designed, optimized, and miniaturized by using CST-MW whose results are compared with other solvers HFSS and ADS. The results obtained by the use of the three EM solvers are in good agreement. After realization, we have tested and validated this antenna. The measurement results of the antenna present a good agreement with the numerical results

A New Configuration of A High Output Voltage 2.45 GHz Rectifier For Wireless Power Transmission Applications

This work deals with the design, simulation, fabrication and experimentation of a novel 2.45 GHz rectifier for wireless power transmission applications. We have designed a voltage multiplier topology rectifier including 5 Schottky diodes known by their low threshold. This rectifier could perform a wireless power supply for many cases where the use of batteries or wires is impossible due to many limitations. The circuit was analyzed and optimized with the Harmonic Balance method provided by the Advanced Design System (ADS). Good performances are observed through the simulated results and confirmed by the fabrication tests in terms of RF-DC conversion efficiency, DC output voltage level and matching input impedance

A Novel Design of a Miniature Metamaterial Antenna for RFID Reader Applications

In this article, we propose a novel design of a dual band antenna based metamaterial for RFID applications. The proposed antenna consists of a rectangular patch using inverted u-slot in radiating element and two split ring resonators loaded in the ground plane. The antenna is printed on an FR4 substrate having athickness of 1.6 mm, permitivitty of 4.4 and loss tanget of 0.025. this antenna is feed by a micostrip line having caracteristique of 50 Ohms. The designed antenna resonates at the UHF band around 900Mz with an input impedance of 87MHz and also, resonates at the ISM band around 2.45GHz with a large bandwidth about 516MHz. The designed antenna is simulated bys using CST and the results is validated by HFSS. After simulation, a prototype of the proposed antenna is fabricated, and the measured results show a good agreement with the simulated one

Design of CW THz PhotonicTtransmitter based on Low Pass-Filter and Bow-tie Wideband Antenna

This paper presents the design of Continuous Wave Terahertz photonic transmitters which is composed from photodetector (PD) associated to a wideband antenna, low–pass filter (LPF) and DC Probe. Firstly, we have developed the bow-tie wideband antenna using an EM solver Momentum integrated in ADS “Advanced Design System”. Then we had optimized a low-pass filter which is responsible of blocking the RF signal providing from the antenna to reach the DC probe. And finally, we have validated into simulation the CW THz photonic transmitter. The three structures are based on multi-layers GaAs substrate, which is the most widely used for THz circuit design. The dimensions of the Whole circuit are 776.788 × 303.39〖μm〗^2

A new configuration of patch antenna array for rectenna array applications

The performance and advantages of microstrip patch antennas made them a field of interest for wireless power transmission applications, especially for rectenna systems where the choice of the antenna is a crucial step.  In this paper, a 5.8 GHz circularly polarized patch antenna has been designed and fabricated, then mounted by using 4 elements to achieve an antenna array to enhance the captured power to be converted by the rectifier circuit. The antenna array is well matched at 5.8 GHz in terms of reflection coefficient and has a directivity of 11dB and a gain of 6 dB. Results have been confirmed by fabrication

Broadband planar 90 degrees loaded-stub phase shifter

The differential phase shifter is an interesting four-port passive microwave network composed of two separate lines, the main line and the reference line, and providing stable phase difference between the two output signals over the specified bandwidth of interest. The most common differential phase shifter is the coupled-line Schiffman phase shifter. In this paper, a novel 90 degrees differential microstrip phase shifter configuration employing a half wavelength transmission line loaded with three open stubs is presented, the proposed design could achieve excellent performance with low phase variation over a wide bandwidth compared to the standard Schiffman phase shifter. The simulated results accomplished with the use of CST Microwave Studio and advanced design system (ADS), were found to be in good agreement and have shown that the proposed loaded-stub phase shifter achieved less than 1.1 dB insertion loss, greater than 13 dB return loss and constant 90±5 degrees phase shift over an 89 percent bandwidth