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In order to implement the fifth generation (5G) communication system for a large number of users, the governments of many countries nominated the low 5G frequency band between 3.3 and 4.3 GHz. This paper proposes a wideband RFPA by designing the input matching network (MN) and output MN of the device using the simplified real frequency technique (SRFT) and the harmonic tuning network. The load-pull and source-pull is applied at multiple points for 100 MHz intervals over the bandwidth to obtain the optimum impedances at the output and input of the 10W Gallium Nitride (GaN) Cree CGH40010F device. To verify the design, the RFPA is simulated, and the performance is measured between 3.3 and 4.3 GHz. According to experimental findings, the measured drain efficiency (DE) throughout the whole bandwidth ranged from 57.5 to 67.5% at the output power of 40 dBm. Moreover, at the 1 dB compression point between 39.2 and 42.2 dBm output power, the drain efficiency (DE) achieves a high value of 81.2% with an output power of 42.2 dBm at a frequency of 3.3 GHz. The RFPA can obtain a maximum gain of 12.4 dB at 3.5 GHz. The linearity of the RFPA with a two-tone signal is measured and the value is less than -22 dBc all over the band. [ABSTRACT FROM AUTHOR]

In this paper, a new microstrip triplexer is designed to work at 2.5 GHz, 4.4 GHz and 6 GHz for mid-band 5G applications. All channels are flat with three low group delays (GDs) of 0.84 ns, 0.75 ns and 0.49 ns, respectively. Compared to the previously reported works, the proposed triplexer has the minimum group delay. The designed triplexer has 18.2%, 13.7%, 23.6% fractional bandwidths (FBW%) at 2.5 GHz, 4.4 GHz and 6 GHz, respectively. The obtained insertion losses (ILs) are low at all channels. These features are obtained without a noticeable increase in the overall size. A novel and simple resonator is used to design the proposed triplexer, which includes two pairs of coupled lines combined with a shunt stub. A perfect mathematical analysis is performed to find the resonator behavior and the layout optimization. The type of shunt stub is determined mathematically. Also, the smallness or largeness of some important physical dimensions is determined using the proposed mathematical analysis. Finally, the designed triplexer is fabricated and measured, where the measurement results verify the simulations. [ABSTRACT FROM AUTHOR]

Microstrip couplers play a crucial role in signal processing and transmission in various applications, including RF and wireless communication, radar systems, and satellites. In this work, a novel microstrip 180° coupler is designed, fabricated and measured. The layout configuration of this coupler is completely new and different from the previously reported Rat-race, branch-line and directional couplers. To obtain the proposed coupler, the meandrous coupled lines are used and analyzed mathematically. To improve the performance of our coupler, an optimization method is used. The designed coupler is very compact with an overall size of 0.014λg2. The obtained values of S21 and S31 are -3.45 dB and -3.75 dB, respectively at the operating frequency, while the fractional bandwidth (FBW) is 56.2%. It operates at fo = 1.61 GHz (suitable for 5G applications) and can suppress harmonics up to 2.17fo. Another advantage of this coupler is its low phase imbalance, while the phase difference between S21 and S31 is 180°± 0.023°. Therefore, our device is a balanced coupler with ±0.3 dB magnitude unbalance at its operating frequency. It is important to note that it is very difficult to find a coupler that has all these advantages at the same time. The proposed 180° coupler is fabricated and measured. The comparison shows that the measurement and simulation results are in good agreement. Therefore, the proposed coupler can be easily used in designing high-performance 5G communication systems. [ABSTRACT FROM AUTHOR]

Symmetry is a key factor for Branch-Line Couplers (BLCs) in RF and microwave systems. This balanced approach evenly distributes power between two output ports, aiding impedance matching and reducing unwanted coupling and crosstalk, while increasing inputoutput isolation. Furthermore, the symmetrical design of BLCs ensures favorable return loss and phase balance, which are essential for phase-sensitive detectors and beamforming. This symmetry also guarantees consistent performance over a wide frequency range, making it suitable for broadband or multi-frequency applications. We present a compact BLC operating in two frequency bands, ideal for 5G sub-6 GHz applications. It uses Tshaped lines with folded lines and stubs in a Minkowski fractal shape, resulting in a size reduction of 90%. The design and simulation were performed using the CST Microwave Studio at 0.7 GHz and 3.5 GHz, achieving a new high frequency band ratio of 5. A prototype on Rogers RT5880 substrate (εr = 2.2, h = 0.787 mm) was tested to validate the design's effectiveness, offering potential for modern wireless applications requiring versatile frequency band operation. [ABSTRACT FROM AUTHOR]

The detection of partial discharge (PD) activities in high-voltage equipment can be conducted according to several mechanisms of signal detection, including electromagnetic wave signal detection, acoustic signal detection, chemical reactions, electrical signal detection, and optical emission detection. Recently, multiple methods of detection and localization of partial discharge activities, which occurred in power transformers and gas-insulated switchgear (GIS), have been proposed to monitor the health condition of high-voltage equipment, especially when the awareness regarding preventive maintenance has been emphasized at the industrial level and among electrical providers. In aligning the needs of the industrial sector and the improvement of PD-detection methods, this manuscript focuses on reviewing the current practice methods for the detection and localization of PD signals in high-voltage equipment, comparing their efficacy, and summarizing the future direction of research work-related methods of PD detection. The comparative reviews are discussed in terms of the mechanism of PD signal detection, indication parameters, calibration techniques, and the advantages and limitations of each method of PD measurement in detail. [ABSTRACT FROM AUTHOR]

Symmetry in designing a microstrip coupler is crucial because it ensures balanced power division and minimizes unwanted coupling between the coupled lines. In this paper, a filtering branch-line coupler (BLC) with a simple symmetrical microstrip structure was designed, analyzed and fabricated. Based on a mathematical design procedure, the operating frequency was set at 5.2 GHz for WLAN and 5G applications. Moreover, an optimization method was used to improve the performance of the proposed design. It occupied an area of 83.2 mm2. Its harmonics were suppressed up to 15.5 GHz with a maximum level of −15 dB. Meanwhile, the isolation was better than −28 dB. Another advantage of this design was its high phase balance, where the phase difference between its output ports was 270° ± 0.1°. To verify the design method and simulation results, the proposed coupler was fabricated and measured. The results show that all the simulation, design methods, and experimental results are in good agreement. Therefore, the proposed design can be easily used in designing high-performance microstrip-based communication systems. [ABSTRACT FROM AUTHOR]

Designing microwave filters with high selectivity and sharp roll-off between the stop and pass bands can be challenging due to the complex nature of the R.F. signals and the requirements for achieving high performance in a limited physical space. To achieve a high selectivity and sharp roll-off rate, this paper presents a compact filter with a triple passband response. The two different passbands at 1.57 GHz and 3.5 GHz are achieved using a step impedance resonator (SIR) with metallic slots perturbation added to the lower corner of the high impedance section of the SIRs, which helps to enhance the filter's selectivity and size reduction greatly. The embedded L-shaped structure originates a third passband at 4.23 GHz, resulting in a triband response with eight transmission zeros below and above the passbands at 1.22/1.42/1.98/3.18/3.82/3.98/4.38/4.53 GHz, respectively. The prototype has low signal attenuation of <1.2 dB and high signal reflection of >25 dB for the three passbands. The fractional bandwidths achieved are 2.54%, 4.2%, and 1.65% at 1.57/3.57/4.23 GHz, respectively, with rejection levels in the stopband greater than 15 dB. Lastly, the structure is fabricated on RO-4350B PCB and observed good matching between experimental and measured results. This demonstrates that the prototype can be successfully implemented in real-world applications such as GPS, WiMAX, and Satellite systems. The area occupied by the filter on a substrate or in a circuit is 0.31 λg × 0.24 λg, where λg is the guided wavelength of the material calculated at the lowest frequency. [ABSTRACT FROM AUTHOR]

This paper proposes a low loss 4 × 4 Butler matrix based on rectangular waveguide cavity resonators technology for millimeterwave beamforming network using iris coupling method. This method has the advantage of controlling the electrical fields and the coupling factor inside a complex medium such as waveguide cavity resonators. The coupling factor of 6 dB for 4 × 4 Butler matrix is achieved by tuning the iris coupling k-value between the waveguide cavity resonators. Thus, avoiding a higher phase difference losses and component losses at upper millimeterwave bands. To validate the proposed method, CST software simulations are performed under several iris coupling k-values to achieve a 6 dB coupling factor. Then, the proposed 4 × 4 Butler matrix is 3D metal printed using selective laser melting (SLM) technique. The measured reflection and isolation coefficients are observed below −10 dB, with coupling coefficients ranging between −6 and −7 dB. The phase differences of −42.02°, 42.02°, −130.95°, and 133.3° are achieved at the outputs. It confirmed that using this proposed method has the superiority over the conventional microstrip and waveguide coupling methods by a 1 dB coupling factor loss and a 3° phase difference error. [ABSTRACT FROM AUTHOR]

The key elements used for receiving and processing signals in communication systems are the bandpass filters. Initially, a common operating mechanism was applied for the design of broadband filters, i.e., by cascading low-pass filters or high-pass filters using multiple line resonators with length quarter-half- or full-wavelength with central frequency, but using these approaches, the design topology becomes expensive and complex. The above mechanisms can be possibly overcome using a planar microstrip transmission line structure due to its simple design fabrication procedure and low cost. So, pointing out the above problems in bandpass filters such as low-cost, low insertion loss, and good out-of-band performance, this article presents a broadband filter with multifrequency suppression capability at 4.9 GHz, 8.3 GHz, and 11.5 GHz using a T-shaped shorted stub-loaded resonator with a central square ring coupled to the basic broadband filter. Initially, the C-shaped resonator is utilized for the formation of a stopband at 8.3 GHz for a satellite communication system, and then a shorted square ring resonator is added to the existing C-shaped structure for the realization of two more stopbands at 4.9 GHz and 11.5 GHz for 5G (WLAN 802.11j) communication, respectively. The overall circuit area covered with the proposed filter is 0.52 λg × 0.32 λg (λg is the wavelength of the feed lines at frequency 4.9 GHz). All the loaded stubs are folded in order to save the circuit area, which is an important requirement of next-generation wireless communication systems. The proposed filter has been analyzed using a well-known transmission line theory, even–odd-mode, and simulated with the 3D software HFSS. After the parametric analysis, some attractive features were obtained, i.e., compact structure, simple planar topology, low insertion losses of 0.4 dB over the entire band, good return loss greater than 10 dB, and independently controlled mutli stopbands, which make the proposed design unique and can be used in various wireless communication system applications. Finally, a Rogers RO-4350 substrate is selected for the fabrication of the prototype using an LPKF S63 ProtoLaser machine and then measured using a ZNB20 vector network analyzer for matching the simulated and measured results. After testing the prototype, a good agreement was found between the results. [ABSTRACT FROM AUTHOR]

A novel three-mode step impedance resonator (TSIR) is developed to design a miniaturized multi-pole microstrip planar ultra-wideband (UWB) filter with independently controlled notched bands at different frequencies is presented in this work. The basic UWB filter consists of four L-shaped λ/4 short-circuited stubs operating in the range of i.e. 2.7 to 12.1 GHz with fractional bandwidth (FBW) 127%, and the TSIR is constructed using two T-shaped λ/2 open ended step impedance resonator (SIR) and one λ/4 short-circuited uniform impedance resonator (UIR) is coupled to the basic UWB design in order to achieve the stopbands performance at 5.1 GHz, 6 GHz, and 8 GHz, to supress the unwanted bands of WLAN, Wi-Fi 6E, and X-band satellite communication system, respectively. Commercial full-wave electromagnetic (EM) software HFSS-13 was used to design an ultra-compact structure having size 0.07 λg×0.02 λg on Rogers RT/Duroid 5880 substrate to justify good agreement between simulated and measured S-parameters. [ABSTRACT FROM AUTHOR]

Reconfigurable antennas have received much attention in RF energy harvesting models owing to their selectivity for operating frequency and polarization. The characteristic of having frequency selectivity and polarization selectivity can be termed as frequency diversity and polarization diversity, respectively. This paper investigates a rectenna device with a new proposed topology in order to eliminate coupling between input and output lines and increase the rectification efficiency with the use of single feed hybrid reconfigurable antenna, switch between 28GHz and 38GHz frequency. Moreover, it is designed to charge a rechargeable battery of 1watt(W). The Reconfiguration mechanism is realized by electronically controlling different states of Switches. PIN Diode (as RLC Equivalent circuit) is used as a switch for ON/OFF states. This antenna mainly comprises rectangular shaped patches (28GHz and 38GHz) with Triango-Truncated edge at the corners. Eighteen PIN Diodes are placed symmetrically throughout the antenna presenting as, S1 & S2 for frequency reconfiguration, S3 to S6 & S7 to S10 connects Triango Truncated edge at the corners for polarization reconfiguration, and for radiation pattern reconfiguration at S11 to S14 & S15 to S18 has been used. The proposed antenna model is capable of simultaneously changing, the radiation patterns as clock and anti-clockwise directions at ±90-degree shift in E and H planes, circularly polarized (CP) states among, Linear Polarization (LP), Right Hand Circularly Polarization (RHCP), and Left Hand Circularly Polarization (LHCP). The current design describes using single antenna for energy harvesting and 5G mobile communication application. This would lead to higher output currents, leading to the ability to efficiently charge a wide variety of batteries. A fully functional prototype has been designed, fabricated and its compound reconfiguration characteristics have been validated for simulated and measured results. For validation of results, the experimental results and the simulation results from the proposed mathematical model were made into comparison, and excellent correlation between the measured and simulated results was obtained. [ABSTRACT FROM AUTHOR]

A novel miniaturized multiband, single-feed microstrip patch antenna is presented in this paper for WLAN and WiMAX applications. Both size reduction and multiband are obtained by etching the Multiple Complementary Split Ring Resonators (MC-SRR) on the ground plane of the normal patch antenna. At first, the normal patch antenna produces a single band of 5.15 GHz; 200 MHz (5.0500~5.2499). Subsequently, a Single Circular Split Ring Resonator (SC-SRR) is etched on the ground plane and produces a triple band of: 3.25 GHz; 288 MHz (3.1085~3.3964), 4.5 GHz; 101.3 MHz (4.4488~4.5501), and 5.22 GHz; 220 MHz (5.1191~5.3400) and Double Single Circular Split Ring Resonator (DC-MCSRR) with: 2.99 GHz; 60.7 MHz (2.9574~3.0181), 3.57 GHz; 324.7 MHz (3.4065~3.7312), and 5.1413 GHz; 115.4 MHz (5.0817~5.1971). The working bandwidths cover the desired frequency bands of WLAN 5.2 GHz and WiMAX 3.3/3.5 GHz. The proposed (MC-SRR) antenna can be employed to wireless communication systems due to its simplicity in design, compactness and miniaturization. [ABSTRACT FROM AUTHOR]

This paper presents a Band-pass Filter (BPF) with a very wide suppressions band. The filter design is based on a modified U-shaped slot. Two pair of Ushaped slots is used to ensure that the filter can suppress the unwanted frequencies up to 4th harmonics. In order to achieve sharp skirt, two transmission zeroes are created near the passband area. Additional transmission zeroes are introduced to deepen the stopband area. Therefore, the passband range starts from 1.3 to 3.3 GHz and the stopband range from 3.3 GHz up to 9 GHz are achieved. The filter performances are verified through simulated and measured results. [ABSTRACT FROM AUTHOR]