Conventionally, diplexers are designed by connecting two filters of different frequencies using a transmission T‐line junction which acts as a distribution network serving the individual filters. Here, a novel diplexer has been proposed and designed to utilize a directly coupled resonator as the distribution network. The directly coupled resonator is designed using two square open‐loop resonators of

A 25 Gbps limiting amplifier (LA) with loss of signal (LOS) detection is presented in this paper. The proposed LA is composed of an input buffer, three‐stage cascaded amplifier, an output buffer, a DC offset cancellation (DCOC) and a LOS circuit. The LA adopts single‐end input and differential output structure to reduce the complexity of optical receiver front‐end and therefore decrease power consumption

We propose a subcarrier‐switching method for all‐optical orthogonal frequency division multiplexing (AO‐OFDM) system. In addition, analysis of the affected neighboring subcarriers, along with the subcarriers being added or dropped, is carried out in a comprehensive manner. After switching operation four times, target subcarrier can still have a Q value larger than 27, while Q value of neighboring orthogonal

A general and simple semianalytical method based on the Galerkin procedure is introduced in this letter for wave propagation problems related to radially inhomogeneous cylindrical dielectric waveguides with arbitrary permittivity profiles. The complicated wave propagation problem in an inhomogeneous waveguide is transformed into a simple problem of solving an equivalent matrix in terms of the Galerkin

In this paper, a novel meta‐grounded planar bandpass filter is presented, facilitating much broader upper stopband. The proposed filter is comprised of a strip layer on the top, a dielectric laminate in the middle and a meta‐grounding layer on the bottom. The strip on the top consists of three cross‐shaped resonators in cascade. Instead of perfect conducting ground, a meta‐ground, composed by a group

In this article, a linear to circular polarization reconfigurable converter (PRC) working in transmission mode is proposed. The PRC's fundamental unit consists of a cascade of half‐hexagon structure and its mirror replica printed on both sides of a single layer substrate. A PIN diode inserted in the central arm of the unit cell controls the PRC's behavior to a ϕ = 45° linearly polarized (LP) incident

Synthesis of phased array antennas generating shaped patterns by exploiting phase tapering only is a challenging problem. A phase‐only tapering permits maximizing the DC to RF power efficiency and results to be particularly useful in satellite applications with stringent constraints on the available power. Such a synthesis is a highly nonlinear problem most effectively addressed via stochastic optimization

A wideband directional coupler based on secondary coupled structure is presented and implemented in this paper. The proposed coupler is formed by two stepped‐impedance shaped microstrip and parallel coupled‐lines with a stepped rectangular slot in a common ground plane. The phase velocity differences between the even‐ and odd‐modes of the coupler are compensated by introducing broadside principal coupling

The group delay of passband window plays an important role in the wireless system. Here we propose a controllable group delay structure based on the multimode electromagnetically induced transparency in a closed waveguide system, which is realized by trapping three “dark” modes with high Q‐factors into one “bright” mode with low Q‐factor. Three transparent windows with three discrete peaks of group

This article presents a pattern‐and frequency‐reconfigurable antenna based on movable liquid metal. The proposed antenna mainly consists of a printed three‐element Yagi‐Uda structure whose two parasitic elements are loaded with slots in the middle. Six movable liquid metal poles are filled in the microfluidic channels, which adhered to the surface of the three radiating arms of the Yagi‐Uda antenna

The concept of a reconfigurable 5GHz microfluidically actuated antenna with beam forming, steering and hoping in a 360° angular range, is presented in this paper. Its architecture is that of a Yagi‐Uda array. Its actuation relies on the electrically controlled vertical displacement of liquid metal slugs inside microfluidic channels without the need of any external actuator. Simulations results along

The novel ridge‐gap waveguide (RGW) technology which uses a full metal structure has many advantages in micro/mm‐wave frequencies such as low loss, broad bandwidth, low sensitivity to manufacturing errors, and easy integration with active components, and so forth. In this paper, a Ku‐band 3‐way Bagley polygon power divider (BPD) is proposed and experimentally demonstrated based on the RGW technology

This letter presents a novel neural network (NN) based digital predistortion (DPD) technique to obliterate the signal impairments and nonlinearities in radio over fiber (RoF) systems. DPD is generally performed with volterra based procedures that utilizes indirect learning architecture (ILA) that can become complex and expensive computationally. The proposed method using NNs evades issues associated

The characterization of antenna radiation patterns in millimeter‐wave (mmW) bands can be particularly challenging. Due to a small wavelength, minute misplacement of the probe antenna in the order of few millimeters can generate substantial errors in the measured pattern. A highly precise measurement system that incorporates a 6‐axis compact robotic arm is implemented to overcome this challenge. System

A miniaturized dual‐mode sector patch bandpass filter using a single via‐hole is presented in this article. Only a single 11.25° sector patch resonator, which is one‐thirty‐second of the complete circular patch resonator, is utilized to miniaturize the filter for the first time. Without changing the size and construction of the initial patch, a simple via‐hole is used to perturb the patch resonator

This article presents an improvement to IEEE 299.1 standard used to measure the shielding effectiveness (SE) of small‐sized metallic enclosures in a reverberation chamber. The shielding quality of radio‐frequency (RF) cables used for SE measurement significantly affects measurement accuracy, especially when metallic enclosures have a high level of SE. A new measurement parameter is introduced to represent

In this article, a compact and high performance 4‐port ultra‐wideband multiple‐input multiple‐output antenna is presented. The proposed antenna is designed by using a novel technology which includes integration of four orthogonal octad‐shaped radiators, four D‐shaped ground planes, multi‐stub techniques and slot techniques. The overall size of the design is effectively miniaturized and the ultra‐wideband

This paper proposes a new feeding topology with internal 180° phase reversal for wideband series‐fed slot array antennas. As a demonstration, a serial fed, half‐wavelength separated, 7‐element array is designed at 5.8 GHz. Comparing with conventional series‐fed arrays, which require one‐wavelength separation, the phase difference between adjacent elements varies less with frequency. Thus, the proposed

In this article, a novel wideband bandpass filter (BPF) with narrow notch band is presented. It is composed of two sets of shunt microstrip‐to‐slotline vertical transitions, a coplanar waveguide (CPW) connecting line, and a meandering half‐wavelength slotline section. Utilizing the synthesis method based on the transmission line network, a four‐pole BPF with Chebyshev equal‐ripple frequency response

The phase‐retrieval method with delayed calibration is widely used in fiber‐optic sensing structures to extract the distributed vibration messages. Yet, the performance of this method is not satisfactory when sudden changes are introduced in sensing path, for the DC compensation is not a slow variable under this situation. To improve the adjustment of interferometric fiber‐optic structure, a self‐tracking

This paper presents three configurations of broadband differentially fed microstrip antenna for GSM1800, 1900 and 2100 MHz. The antennas are designed and fabricated using two different substrates for bottom and upper layer. The three antennas designed and tested have gain of 9.88, 9.66, and 11.14 dBi, respectively, at the center frequency. The proposed antennas also find its implementation in areas

In this study, a novel scheme is proposed for bidirectional beamforming using time‐modulated linear arrays (TMLAs). A beamforming method with a time shift was adopted to obtain the bidirectional pattern with the +1st harmonic using two switching sequences. Furthermore, the genetic algorithm was modified to obtain an additional beam using the fundamental component. In the proposed approach, the direction

A low‐profile, wideband, high gain artificial magnetic conductor (AMC) integrated monopole antenna is proposed in the letter. The bowl‐shaped stair styled monopole with defected round type partial ground is integrated with the AMC containing 2 × 2 unit‐cells to broaden the impedance bandwidth by 92.7%/66.2%/53.9% at the three resonating notches at 6/8.4/10.3 GHz respectively. The AMC has covered ±90°

In this article we present a method for the rapid design of wideband, high efficiency metamaterial GRIN lenses with rotational symmetry. The method achieves rapid optimization by reducing the number of optimized parameters while maintaining wideband impedance matching for high aperture efficiency. For rotationally symmetric lenses with isotropic GRIN media it is sufficient to design a two‐dimensional

In this paper, a wideband dual‐polarized magneto‐electric (ME) dipole antenna with modified electric‐dipole structure is proposed based on the cost‐effective printed circuit board (PCB) technology for millimeter‐wave (mmW) applications. A 3D‐meandered electric‐dipole design is adopted to enlarge the operating bandwidth without increasing the physical volume and footprint of the antenna structure. The

The time‐domain finite‐element method (TDFEM) is extended to study the two‐dimensional transient electromagnetic scattering from multiple targets above a rough surface in this article. The perfectly matched layer is employed as the truncation boundary of TDFEM region to absorb the outward wave scattered from the model. To introduce the incident wave, a total field boundary, which splits the whole region

A wideband reconfigurable analog predistorter (APD), which can maintain the tuning capability in wideband frequency, is proposed in this letter. First, the requirements of tunable impedance matching network (TIMN) used in the wideband reconfigurable APD is given. Second, a new wideband TIMN is analyzed, and the coverage the proposed TIMN is given. Then the circuit parameters of the TIMN can be appropriately

This letter discusses the design, manufacture, and characterization of a substrate‐integrated waveguide E‐plane tapering. The tapering facilitates the integration of two waveguides with varying heights for, that is, conductor‐backed coplanar waveguide to rectangular waveguide integration. A simultaneous top‐ and bottom‐sided, λ/4‐based stepped tapering for the 71–86 GHz band is designed using low‐temperature

In this paper, an electromagnetic band gap structure with fractal geometry based on Peano curves is proposed to suppression of degenerated modes. The geometry is characterized by the inclusion of air slots into the substrate, under the feed line, of a rectangular microstrip patch antenna. The parameters analyzed are the input impedance using the Smith chart, the reflection coefficient (S11), radiation

An unconventional, yet quasi‐modular base station phased array architecture synthesis technique is proposed for multiuser fifth‐generation applications. By keeping uniform amplitudes and linearly progressing phases at the elements of an optimal irregular array, power‐efficient side lobe suppression is achieved for effective inter‐user interference mitigation. The layout irregularity is achieved within

The time domain expression of the lightning electromagnetic fields (LEMF) contains multiple integration processes, and the direct solution tends to take up a lot of calculation time. In this paper, the structure of the time domain expression of the LEMF is analyzed, the idea that using the matrix pencil method to realize the fast evaluation of the LEMF is proposed, and the feasibility of this method

A novel in‐line half‐mode substrate integrated waveguide (HMSIW) bandpass filter with interdigital slots has been proposed in this letter. Here, the interdigital slot shows attenuation resonance characteristics and generates a finite frequency transmission zero (TZ). The proposed filter generates two TZs without additional coupling or extra space and exhibits wide stopband characteristics. To validate

A compact dual‐polarized beam‐switching patch antenna with large tilted angle is presented in this paper. The antenna is a Yagi–Uda patch antenna, which consists of one driven patch and two parasitic elements. Two PIN diodes are placed across the slots of the complementary split‐ring resonator to switch the function of the corresponding parasitic element between director and reflector. By properly

A polarization‐independent reconfigurable frequency selective rasorber (FSR)/absorber with low‐insertion loss (IL) based on diodes is proposed in this article. The presented structure consists of a lossy layer based on square loops and a bandpass frequency‐selective surface. These two layers are separated by an air layer. Each layer has an embedded bias network that provides the bias voltage to the

In this paper, a WR‐1.5 band (500–750 GHz) 3rd order waveguide bandpass filter has been designed and fabricated using high precision computer numerically controlled metal micromachining. The filter has been measured with a 7.29% (48.7 GHz) bandwidth at the center frequency of 667.5 GHz. The minimum passband insertion loss is measured to be 0.87 dB and the measured return loss is better than 10 dB across

In this research, a highly efficient single‐layer reflective polarization converter based on anisotropic metasurface is proposed for microwave communications. The periodic design works in a dual‐operation mode as a half‐wave plate (cross‐polarizer) and a quarter‐wave plate (circular‐polarizer) over multiple frequency bands. The unit‐cell is comprised of coupled D‐shaped resonators printed on a low‐cost

This article presents the multiband asymmetric radio frequency (RF) to direct current (DC) converter circuit for the wireless power transfer (WPT) applications. The proposed circuit is composed of a power divider, novel asymmetric multiband matching circuit and RF Schottky diode quadrupler voltage rectifier circuit. Unlike the conventional narrow band quadrupler using two Greinacher cells with opposite

Photonic signal processing is a suitable alternative of electronics based processing for wideband frequency detection. We propose a novel technique for the detection of a wide range of frequencies based on photonic signal processing. The unknown frequency to be measured is used to modulate a tunable optical source by implementing single sideband suppressed carrier modulation. The modulated signal is

This letter shows that the synthesis of coplanar waveguides with finite substrate thickness can be obtained by simple numerical solution from the exact quasi‐static formulae of the characteristic impedance using bisection method The novelty of the method is that accurate synthesized values compared to those from curve fitted formulae are obtained. Moreover, sophisticated numerical techniques are not

This article compares the humidity sensing performance of microwave sensors coated with a poly(methyl methacrylate), poly(2‐hydroxyethyl methacrylate), or poly(vinyl alcohol) (PVA) polymer. A microwave sensor based on a modified interdigital‐capacitor‐shaped defected ground structure (IDCS‐DGS) in a microstrip transmission line with enhanced permittivity sensitivity was designed on an RF‐301 substrate

Compact microstrip bandpass filters using triple‐mode resonator are investigated in this paper. At the center frequency of 2.45 GHz, a half‐wavelength microstrip open‐circuited resonator is loaded with a chip capacitor and a chip inductor to realize the triple‐mode resonator. By adjusting the resonator's parameters, the first three resonant mode frequencies could be tuned for bandpass filters with

Two decoupled antennas, comprising two feeding monopoles and one dipole shared by the monopoles, for the fifth‐generation (5G) multi‐input multi‐output (MIMO) applications are proposed. The feeding monopoles are placed on both sides of the coupled‐fed, common dipole. First, to operate in the 3.3–5.0 GHz 5G wideband, two resonant modes at about 3.6 and 4.7 GHz, contributed to by the common dipole and

This paper presents 28 GHz GaAs front‐end IC for 5G beamforming systems with single positive supply voltage. A 28 GHz front‐end IC consists of a 3‐stage power amplifier, a 3‐stage low noise amplifier and two reflective type single pole double throw switches in 0.15 μm enhancement‐mode (E‐mode) GaAs pHEMT technology. The proposed 28 GHz front‐end IC is controlled only with single positive supply voltage

In this letter, a complementary split‐ring array (CSRA) for decoupling compact (edge‐to‐edge spacing of 0.078 λ0) 2 × 2 circularly polarized (CP) microstrip antenna is proposed. The CSRA is the ground plane with the etched split‐ring array (SRA) which is composed of 12 split‐rings. Each element is surrounded by four etched split‐rings, and the two adjacent elements share the same etched split‐ring

High‐order pulse modulations in free space optics (FSO) communication are of practical value, and non‐Kolmogorov gamma–gamma (GG) channel model is the most suitable for FSO channel. However, research on a system combined with the above is rarely reported. In our work, we propose high‐order (4*32 and 4*64) amplitude and pulse position modulation (APPM) and overlapping amplitude and pulse position modulation

A new miniaturized ultra‐wideband antenna with sufficient dual‐band rejection in WiMAX and WLAN bands is reported. The antenna uses the conventional rectangular patch radiator with built‐in sectorial and Inverted‐U slots to achieve the required dual‐band rejections. A coplanar waveguide feed line has been used to achieve the ultra‐wideband operation. The design has been implemented on 1.6 mm thick

A methane telemetry system for 1653 nm DFB laser based on TDLAS‐WMS technology is developed in this article. The focus tunable lens is used as the collimating system of the telemetry device to solve the problem that the telemetry device cannot be dynamically adjusted under different detection environments. Experimental results show that the root mean square error was 7.6205 and the theoretical limit

In this article, we demonstrate a reconfigurable antenna concept based upon a film of vanadium dioxide (VO2) with embedded metallic surface inclusions to increase radiation efficiency. We fabricate a monopole antenna with the proposed film, demonstrate a good match between measurement and simulation, and propose methods for increasing performance. We show that the addition of metallic inclusions in

In this letter, a distributed element‐based load network is proposed for designing a high‐efficiency dual‐band (DB) 5‐W Class‐E power amplifier (PA), at two widely spaced frequencies of 2.4 and 5.8 GHz. This network consists of two different stages. The first stage deploys a flexible network configuration with crossed transmission lines (TLINs) to provide concurrent DB fundamental matching in a closed‐form

A dual‐resonant, semi‐circular sector patch antenna is properly incorporated to a planar self‐balanced magnetic dipole antenna and lead to a novel triple‐resonant, dual‐band planar antenna which has characteristics of wide E‐plane beam width and stable gain at both bands in this work. Design approach with a group of approximate closed‐form formulas is proposed to initially calculate value of the main

In this article, a graphene‐based reflective metasurface which can generate Bessel beams at arbitrary directions is proposed at 1.52 THz. It chooses the classical cross structure as the unit cell and extends the coverage of the reflection phase to 360° by adjusting two key parameters while maintaining a relatively high‐reflection amplitude. Combined with the excellent impedance characteristics of graphene

In this work, all fiber temperature measurement based on change of light polarization is demonstrated using tapered fiber coated with graphene. The large evanescent field of tapered fiber allows graphene to absorb the surrounding heat and subsequently this changes the refractive index of graphene coated tapered fiber. The change of refractive index is due to thermo‐optic effect. When there is a change

We present a high‐fidelity measurement‐based nonlinear model of low‐complexity millimeter‐wave transmit and receive circuits for design and analysis of 1‐bit on‐off‐key (OOK) massive MIMO wireless communications systems. The receive model is based upon a fabricated 38 GHz energy detector, representative of state‐of‐the‐art OOK millimeter‐wave receivers. The model is validated with measurements and

In this study, an improved RF CMOS transistor compact equivalent circuit model is presented. Due to the finite resistivity of the substrate, the magnetic coupling effect between the interconnection line and the substrate affects the signal propagation at mm‐wave frequency range. To characterize transistors in the terahertz band, a sophisticated network is introduced to represent the magnetic field

A W‐band injection‐locked frequency divider (ILFD) with modified transformer coupling resonant is demonstrated and implemented in a 40‐nm CMOS technology. The locking range and operation frequency of the ILFD is improved without increasing chip area or circuit complexity. The measured locking range of the ILFD covers from 86 to 104 GHz. The measured phase noise of the modified W‐band ILFD is −114.89 dBc/Hz

This paper presents a dual band bandpass filter by loading two semi‐circular mushroom resonators (ScMRs) inside the cavity of a circular substrate integrated waveguide (SIW). TM101 and TM201 modes of the mushroom resonator loaded circular SIW cavity are excited to generate the first and second passbands respectively. As the proposed bandpass filter is based on circular SIW cavity, the passbands of

We present a tunable multistacked metamaterial‐based graphene grating structure for the lower THz frequency range. Circular gold wire is placed between graphene layers to obtain wideband response. Reflectance, transmittance, absorption, and refractive index parameters are analyzed for metamaterial‐based graphene grating structure. The results show wideband reflectance response ranging from 1 to 2.5

A lightweight multi‐input multi‐output (MIMO) two‐element wearable ultra‐wideband (UWB) antenna having a port isolation of greater than 21 dB is introduced in this communication. The proposed structure includes wearable jeans cloth as a substrate, wherein two inverted u‐formed stubs are mounted in the middle position located on the backside of antenna and attached to the partially etched ground for

This paper presents a rigorous theoretical analysis of a thulium doped fiber amplifier (TDFA) operating at around 1900 nm. The performance of the amplifier is analyzed based on the concentration of Tm3+ ions, TDF length, and the pumping power, respectively. A broadband gain of around 41 dB is demonstrated for a Tm3+ doped fiber length of 10 m, and an optimized pump power of 400 mW, while employing

A novel compact multilayer multibeam antenna array based on substrate integrated waveguide (SIW) is proposed in this letter for 5G millimeter wave (mm‐wave) applications. A multimode beam forming network (BFN) cascaded by phase compensation and coupling structures is folded to make the antenna array more compact. The phase difference between the output ports of traditional multimode beamforming network