ABSTRACT This paper presents a wideband low noise amplifier (WBLNA) for the 2–11 GHz band with high linearity and low power consumption. The proposed WBLNA is designed based on the inverter‐connected capacitive cross‐coupled topology in 0.13 µm CMOS technology. The presented circuit utilises the well‐combination of recently published techniques, including inductive source degeneration, inductively series‐peaking common source stage, capacitive cross‐coupled common gate topology, complementary push‐pull and current‐reuse architectures and noise cancellation methods. An analytical solution is presented for the proposed structure, where the analytical results are compared with the pre ‐and post‐layout simulation results. The post‐layout simulation results demonstrate a high and flat S 21 of 19.6 ± 0.5 dB over the entire frequency band. In addition, the proposed structure meets the minimum noise figure of 2 dB at 9 GHz while consuming 6.01 mW from a 1.2 V power supply. The process voltage temperature simulations are also reported in this work, in which correct operation was observed for all scenarios. The proposed WBLNA can be used to integrate different wireless technologies into post‐5G wireless systems.

This paper proposes a method for estimating the excitation of array antennas by backward-transforming phaseless field data into the very near-field. The very near-fields are reconstructed at the antenna aperture using the Tikhonov source current reconstruction method (SRM). Two field amplitudes in different planes recover very near-field data from phaseless fields. The excitation estimation technique relies on the localised nature of very near-field currents around the antenna. Through spatial filtering of the reconstructed equivalent currents, the current distribution of each individual element is isolated. The excitation of each array element is then determined by analysing its current distribution over a separate surface mesh. Excitation estimations of two different array antennas with measurement and simulation results have been carried out to validate the proposed method. The relative amplitude errors of the excitation estimation with simulation data are 7.5% and 3.9% for using equivalent electric and magnetic current, respectively. In the measurement scenario, which includes the errors of manufacturing and testing, the maximum relative amplitude error is about 12% and the maximum phase recovery deviation is about +/- 9 degrees.

This paper presents a compact broadband 4 x 4 Butler matrix (BM) with high input return loss and without crossover components. The design employs four broadband 90-degree hybrids, each achieving 49% fractional bandwidth at a center frequency of 3.5 GHz with input return loss greater than 30 dB. The complete BM has a 20 dB return loss bandwidth of about 37% from 3 to 4.4 GHz and an insertion loss of less than 0.5 dB at the center frequency. Such high input return loss and low insertion loss are highly desirable in base station applications. A prototype of this structure is fabricated, and the measurement results are compared with the simulations. The measurement results show that this BM can cover 5G bands of N77 (3.3-4.2 GHz) and N78 (3.3-3.8 GHz) as well as the LTE bands 42 (3.4-3.6 GHz) and LTE band 43 (3.6-3.8 GHz) with 0.5 dB insertion loss, +/- 9 degrees phase variations, and stable beamforming across 3.0-4.4 GHz. These features make the design highly suitable for 5G base station applications.

This paper proposes a highly linear, wideband low noise amplifier (WBLNA) with differential structure in 0.13-mu m CMOS Technology. The proposed WBLNA is designed for a 2- to 6-GHz band that covers multiple standards, such as Bluetooth, Wi-Fi, 3G, 4G, and 5G sub-6-GHz band. The presented circuit utilizes a well combination of recently published techniques, including inductive source degeneration, inductively series-peaking common source stage, cross-coupled topology, distributed structure, and noise cancelation methods. Moreover, the proposed amplifier utilizes feedforward and complementary techniques to attenuate both second- and third-order nonlinearity effects and improve the nonlinearity favorably. According to the post-layout simulation results, the proposed LNA achieves input return loss (S11) lower than -10 dB, input third-order intercept point (IIP3) in between 13.42 and 13.48 dBm, flat noise figure (NF) of 3.4 +/- 0.2, and flat power gain (S21) of 12.93 +/- 0.2 dB over 2- to 6-GHz frequency range. Furthermore, the proposed circuit meets the average input second-order intercept point (IIP2) of 64.5 dBm at 6 GHz and figure of merit (FOM) of 30.05 GHz while drawing 16.73 mA from the 1.2 V power supply.

The design procedure of a novel compact ultra-wideband (UWB) filter with high selectivity and low insertion loss is presented in this paper. The proposed filter consists of a simple planar combline filter at the top of a substrate and a non-intuitive shape of the defected ground structure (DGS) on the other side. The UWB filter is obtained by optimizing the shape of DGS and the combline parameters with a mixed integer genetic algorithm. The mixed integer genetic algorithm optimizes both continuous and binary values simultaneously. The continuous values define the combline parameters while the binary values define the shape of DGS. The detail of the design procedure is presented and validated by fabricating a prototype of the proposed filter. The measured insertion loss of the proposed filter in the mid-band frequency is less than 0.5 dB. The measurement results also show that the proposed UWB filter with a very compact structure has five transmission zeroes at the upper and lower stop bands.

Designing metasurfaces is a challenging task. Traditional methodologies, which primarily depend on iterative procedures, are both time-intensive and require specialized expertise. The proposed algorithm uses conditional deep convolutional generative adversarial networks (cDCGAN) to design metasurfaces. This method instantly create a 2D image of a multi-layer metasurface using the scattering parameter S11 as the input vector. The algorithm significantly reduces the size of the training dataset by applying pre-training and post-generating steps. The pre-training step involves aliasing and modifying images using a limited color palette. The post-generating step consists of separating the color channels, converting the pixels to vector based images, and fine-tuning the borders. The algorithm is evaluated for three metasurfaces that have unique features compared to the training dataset samples: a single-band metasurface unitcell, a dual-band metasurface unitcell, and a partially trained sample improved by magnetic field analysis. The results show that the proposed algorithm can accurately predict the images of these metasurface unitcells, demonstrating its potential for fast and efficient metasurface design.

Designing metamaterials involves computationally intensive tasks, resulting in a time-consuming design process. A deep learning approach is proposed to generate metamaterial designs directly from the input S-parameter diagram. Furthermore, to address the challenge of creating the input diagram, a fine-tuned Large Language Model (LLM) generates the S-parameter diagram based on user input prompts. Compared to traditional neural network methods, the use of an image-based deep learning network enhances the architecture by minimizing the pre and post-processing steps required to transform a metamaterial unitcell image into an numerical array, and vice versa. Simulation results confirm the agreement between the generated metamaterial and the desired input response.

In this paper an array of conformal antennas with switched beam patterns is presented. The array antenna consists of three $\mathbf{U}$-shaped cavity-backed slots, mounted on a cylinder. The proposed antenna has a 5.5% fractional bandwidth in the ISM band of 433 MHz. This ISM band is used in Internet of Things (IoT) devices and smart city applications. The cavity-backed structure of the proposed antenna increases the antenna gain while the conformal shape increases the half-power beamwidth. Each antenna of the proposed scheme has a gain of about 3 dB and a saddle radiation pattern with a half-power beam width (HPBW) of $\mathbf{1 2 0}$ degrees. Therefore, three examples of the proposed antenna can cover the $\mathbf{3 6 0}$-degree horizon with the beam switch network. The cylinder shape of the proposed antenna is suitable for urban traffic lights in smart traffic control systems. The proposed antenna is simulated with both time and frequency domain techniques using CST software, where results are greatly matched in both simulations.

In this letter, a helical slot antenna for generating multiple orbital angular momentum (OAM) modes is proposed. The proposed antenna consists of four concentric helical slot array antennas, which are excited by an annular microstrip line. The number of each helical slot, and length of microstrip feed are chosen to create circularly polarized OAM modes of 0, −1, −2, and −3 at 3.5 GHz frequency with more than 10% fractional bandwidth. The final multimode antenna has 89 mm in diameter and 19.1 mm in height. A prototype of the proposed compact antenna is fabricated. From the simulation and measurement results, prominent spiral phase planes are observed at all antenna ports. Both the measurement and simulation results show that the proposed compact antenna has valuable features to produce different vortex modes.

The national information network is being implemented with the aim of providing the services needed by the people through internal infrastructure and independent of international internet platforms. Considering the geographical diversity of the country and in order to increase the reliability coefficient and access penetration coefficient in the national information network and also due to the needs of future services, it is not possible to rely solely on fiber and the use of satellite communications will be unavoidable. At present, satellite communication has not reached a worthy position in the country's communication network and is limited to some applications such as banking, oil and gas etc. However, due to the development of broadband networks and the increasing need for high-speed data transmission and the increase in data volume, as well as creating social justice and increasing the speed of access, as well as the Internet penetration rate in the country in order to access various services, it is necessary to develop satellite communications to should be taken seriously. In this regard, an analysis of the market of several categories of services in Iran has been done so that the amount of gap in the amount of service provision and the amount of need to receive services can be seen.

In this paper, the design and simulation of an ultra-high power rotary joint for X-band frequency are discussed. The proposed rotary joint consists of a mode converter at the beginning and the end, a contactless circular waveguide, and an external choke including ball bearings and impedance-matching stubs in the middle part. At the beginning and the end parts, by converting the TE 10 mode of a rectangular waveguide to the TE 01 mode of a circular waveguide, a symmetrical mode is created, which enables successive rotations of the structure without disturbing the electrical current. The use of circular TE 01 mode in the proposed rotary joint leads to the power handling of 52 megawatts in the structure. The middle circular waveguide consists of choke and stubs for matching the contactless circular waveguide. The simulation results show that the proposed structure has a transmission loss of less than 0.4 dB and a return loss of better than 15 dB in the 10 GHz frequency.

Satellite mega constellations such as Starlink already provide broadband service around the world from space with thousands of low earth orbit (LEO) satellites. This new technology has several advantages such as increasing network coverage, providing service in disasters, reducing latency, increasing reliability, etc. In addition, this technology has disadvantages such as increased interference, reduced sky visibility, reduced monitoring of national networks, and security vulnerabilities. Different opportunities and threats will also arise in terms of this technology for countries, communities, and industries. This paper reviews the latest state of the mega constellation technology and satellite internet and analyzes the Strengths, Weaknesses, Opportunities, and Threats (SWOT) of this technology. The presented SWOT analysis is based on various news, numerous articles of experts, and follow-up groups around the world, and in a way, all the positive and negative aspects of mega constellation technology and satellite internet will be reviewed in the paper. Finally, suggestions will be provided to deal with this new technology.

In this article, an algorithm for the phaseless near-field (NF) to far-field (FF) transformation based on the source current reconstruction method (SRM) is proposed. The algorithm starts with decomposing the equivalent currents of the antenna under test (AUT) into a deterministic and ambiguous current. The deterministic portion of the current is determined from the phaseless signal subspace-based optimization method (SOM), while several iterative forward-backward propagations add the ambiguous portion. It is shown that with the SOM initialization, no further prior information about the antenna under test is needed and the iterative scheme can converge to the desired result within a few iterations. A simulation and a measurement example validate the proposed algorithm. All results show an accurate, fast, and stable phaseless field transformation is obtained.

Orbital angular momentum (OAM) is a promising feature of electromagnetic (EM) wave to increase the communication link capacity. It is possible to use the OAM over the whole spectrum from radio frequency to optic. EM waves would experience a vortex phase boundary while transmitting the data. According to the infinite number of vortex modes, there would be infinite data transmission in theory. Here, a plasma medium with a complex structure is exploited to construct the vortex phase plane at microwave frequencies. Plasma as the ionized gas transmits, reflects, and absorbs EM wave under some conditions. The ratio of plasma physical parameters with the impinging wave frequency presents the condition of wave interaction with the plasma medium. A reflector plane is realized with the help of multilayered low-pressure plasma. By radiation of a plane wave toward the reflector surface, vortex beams of several modes are realized. The controllability of plasma electron frequency makes it a reconfigurable reflect-array antenna for vortex beam generation. The design is based on the scattering theory of the dielectric plasma model for a vast frequency of 8-16 GHz. The proposed advanced EM structure to generate the vortex beams is simulated with a full-wave analysis that verifies the studied design.

Orbital angular momentum (OAM) as vortex wave has potential application for dense communication. A multi-slot antenna is proposed based on Archimedean spirals to generate/detect the OAM waves. The antenna equips three radiation slots in a disk-manner to realize three different OAM modes simultaneously. A serial-fed microstrip array is designed for circularly polarized (CP) radiation. The lengths of the slots and microstrip lines are chosen to radiate at 3.5 GHz with 20% fractional bandwidth. So, it can identify the receiving modes of vortex wave with this mechanism. A prominent spiral phase plane is observed for the generated OAM wave. In addition, the far-field pattern presents a doughnut-shape beam. The whole antenna is fabricated on a 13 cm printed circuit disk board. Both the experimental and simulation results show that the proposed antenna has valuable features to produce different vortex modes.

This paper describes the concept and design of a novel miniaturized tunable blade antenna for UHF frequencies. The proposed antenna consists of two trapezoidal patches separated from each other at the feeding position. At the top trapezoidal patch, several horizontal slots are etched creates a miniaturized radiating structure. A series capacitor and a parallel inductor are also used at the antenna feed point. This matching network can tune the antenna resonance in about 100 MHz around the center resonant frequency of 300 MHz. The overall dimensions of the proposed antenna are 180 × 192 ×1.6 mm 3 , A prototype of the proposed antenna is fabricated and the simulated results are compared with the measured ones. The radiation results show that the antenna has 1 dBi gain at its resonance frequency with less than -15 dB cross polarization.

This study describes the concept and design of a low-cost super broadband dipole antenna with a passive matching network. The proposed dipole antenna is designed in three steps. First, a simple planar dipole antenna with six different loads and a balanced to unbalanced (Balun) transformer is designed by the genetic algorithm optimisation. The position and value of the loads are optimised to achieve an acceptable radiation pattern and voltage standing wave ratio (VSWR) over the desired frequency bandwidth. In the next step, the shape of the printed strip dipole antenna is optimised to improve the frequency response of the designed antenna. Finally, an LC network is added to the antenna feed point to reduce the antenna VSWR at low frequencies. The final dipole antenna has a length of 1.7 m and can operate over 30–1200 MHz with VSWR ˂3 and broadside gain >−10 dBi. The proposed antenna can easily be fabricated at a low cost via the printed circuit board technology. An industrial prototype of the proposed antenna is fabricated and measured. A good agreement between measurement and simulation results is observed.

This paper represents a new dual‐mode waveguide filter based on a stereometamaterial resonator. A novel resonator is proposed in the paper consisting of two stacked complementary split ring resonators (CSRR) where one of them is twisted in its plane. This resonator provides a transmission zero, which can be easily adjusted in both of the upper and lower stopbands of the filter. By cascading the four of the proposed resonator, an eight order symmetric filter with four transmission zeros are designed. The filter parameters are optimized using the genetic algorithm (GA). This filter is fabricated and the experimental results are in a good agreement with the simulation data. Besides the flexibility in the design, the most important characteristic of the proposed structure is its compactness compared to similar structures.

In this article, a decoupled source current reconstruction method (SRM) for noisy and reactive near-field (NF) to far-field (FF) transformation is introduced. It is shown that the traditional SRM for NF/FF transformation shows instability in the regions that the amounts of noise or reactive radiations are noticeable. Therefore, in these regions, equivalent currents should be determined from a Tikhonov SRM equation. However, this equation increases the computational cost of the SRM. To simplify the Tikhonov SRM equation, a Tikhonov radial field retrieval algorithm is also proposed. In this algorithm, the Tikhonov integral equation is decoupled by considering and retrieving the radial components of the electric field. Results of far-field calculation with both the proposed Tikhonov SRM equation and Tikhonov radial field retrieval algorithm with three different antennas are presented and compared with those of the full-wave simulation and measurements. The results show more accurate field transformation with the proposed algorithms.