Article Frontmatter was published on July 1, 2021 in the journal Frequenz (volume 75, issue 7-8).

In this paper, the solution of the H-polarized wave scattering problem by infinite graphene strip grating is obtained. The structure is periodic except two neighboring strips. The distance between these two strips is arbitrary. In particular, such a problem allows to quantify the mutual interaction of graphene strips in the array. The total field is represented as a superposition of the field of currents

The electromagnetic scattering characteristics of foam in Marine environment are studied in this paper. The Elfouhaily sea spectrum model is established, and the dielectric constants of seawater/ocean foam are calculated based on the double Debye dielectric constant model, furthermore, the formula relation between them is given. As an important factor affecting ocean electromagnetic scattering, the

The Capon beamformer has excellent resolution and interference suppression capability but due to various attributes of practical environment such as inaccurate and/or insufficient information about the source, transmission medium and antenna array its performance deteriorates. To enhance its performance various efforts have been devoted and one effective method is presented here. In this paper, a novel

This article proposes a design and implementation of array Microstrip Patch antenna of configuration 2 × 2 at an operating frequency of 3.5 GHz. The proposed design takes a dimension of 80 mm × 92 mm × 1.6 mm with four radiating elements arranged in rectangular form with an optimized separation between the patches. All the radiating elements were connected through a corporate series network with an

Microwave sensing is important to measure the permittivity of the materials or detecting a material. In this current work, a compact antenna for WLAN application with circular polarization is designed. We are supposed to use it as a sensor to determine the permittivity of industrial oil. For calibration of the sensor, the gasoline and petrol are utilized based on Debye theory and also butanol is checked

A compact tunable notch band ultra-wideband (UWB) antenna is implemented. The band notch characteristics have been obtained by placing a square-shaped metallic loop in the upper ground plane connected via PIN diode. The obtained notched frequency bandwidth can be altered by changing the states of the PIN diode. UWB response with narrow-band notch operation is observed when PIN diode is in ON state

In this paper, a bandpass filter (BPF) has been designed using bent and coupled-line structure. The design process of the filter to achieve a BPF with good characteristics is completely explained. Therefore the LC equivalent circuit of The BPF is presented as the analytical description. The proposed filter can pass frequencies between 2.2 and 3.6 GHz with an insertion loss <0.4 dB, which is suitable

In this paper, a novel four-band diplexer using defected ground structures with compact size, low insertion loss and high isolation is presented. To begin with, there are 16 defected ground stepped impedance resonators (DSIRs) controlling four passbands characteristics. Every four DSIRs can generate one passband. Then, four different DSIRs use the same feeding line. According to the group delay, we

This paper communicates the design and experimental validation of dual-band SIW power dividers (single-stage and double-stage) with arbitrary power division. The dual-band power dividers are developed for WiMAX (3.5 GHz) and WLAN (5 GHz) applications. The proposed SIW power dividers are realized by a rectangular cavity, two rows of metallic-vias and one pair of unequal complementary split-ring resonators

In this paper, a new reconfigurable power divider (PD) is proposed to improve the efficiency of the three-way Doherty power amplifier (DPA). The conventional λ/4 transmission line is replaced by the proposed reconfigurable PD in the input of peaking amplifier, where the 90° phase shift and impedance matching can be achieved. Furthermore, the output power distribution ratio (PDR) can be continuously

Article Frontmatter was published on May 1, 2021 in the journal Frequenz (volume 75, issue 5-6).

This paper presents a compact and the low-cost coupled line band-pass filter with application to future generation millimetre-waves and 5G communications. The proposed approach of the filter design is based on the coupled-line and centre tapped upper and lower stepped impedance resonators. These resonators generate the sharp rejection, wide bandwidth, and abet to realize the compact filter. A detailed

This paper presents a novel design of rigid coaxial line based variable stub tuner. It incorporates controlled drive for the movement of shorting ring along the length of the stub inside the coaxial line. The ring is housed inside stub through linear slot over the coaxial conductor. Inbuilt slot at outer conductor of coaxial line introduces undesirable discontinuity which deteriorates the performance

In this paper, two types of coaxial coupler and waveguide coupler for different frequency helix traveling wave tubes (TWTs) are designed, fabricated and cold tested. The coaxial coupler includes of window ceramic and RF transformer section. At present multi-section impedance transformer design approach is used for wideband helix TWTs. In any helix TWT, impedance of the source is transformed to the

For the next generation wireless networks, backhaul links with data rates of several Gbit / s are required. Line-of-Sight-MIMO with optimally arranged antennas can exploit the full multiplexing gain of orthogonal MIMO streams to achieve high throughput, as shown in recent works utilizing the 60 GHz mm wave band. In contrast, conventional MIMO systems operating at sub-6 GHz carrier frequencies, as utilized

Here, a planar Ultra-Wideband (UWB) wearable Multiple Input Multiple Output (MIMO) antenna is designed for on-arm wearable Wireless Body Area Network (WBAN) applications. This antenna is designed on a 100% cotton cloth substrate. The two-port MIMO antenna has a dual spinning wheel shape like radiators with the partial ground and microstrip feedings. The two partial grounds are connected to a rectangular

In this article, cross-shaped metallic parasitic strips based two radiator element multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) is excited by quadrature wave transformer microstrip feedline, designed, simulated and fabricated for ultra-wideband (UWB) applications. The proposed MIMO antenna structure is implemented with the help of two rectangular-shaped radiator elements

A two-port multiple input multiple output (MIMO) dielectric resonator antenna is proposed where two orthogonally connected feed lines are combined to unite two orthogonally produced modes. The feed lines build a hybrid network. The backplane is defected by a circular defected ground structure (CDGS), which is extended by two rectangular slits placed orthogonally with the input ports. The antenna uses

Conical Terahertz DRA (dielectric resonator antenna) have been designed and investigated at terahertz spectrum i.e. 10 THz. Lower terahertz frequency band is useful for high data speed communication and upper band is used for optical sensors and free space wireless communications. Novelty in this work is to open up research in. terahertz. A unique geometry based dual band terahertz DRA with mathematical

We present the design of a compact tri-band adhesive planar antenna which operates as a gateway for biomedical applications. Operating in the Industrial, Scientific and Medical (ISM) band (2.4–2.5 GHz), the Institute of Electrical and Electronics Engineers (IEEE) 802.15.6 Wireless Body Area Network Ultra-Wide Band (WBAN UWB) (3.1–10.6 GHz) and the IEEE 802.11 Wireless Local Area Network or WLAN (WLAN)

A slot loaded annular sector microstrip antenna having a pentaband operation is presented. The antenna has six resonant frequencies and the fourth band occurs between the fourth and fifth resonance. The radiation pattern is linearly polarized at all the frequencies. The radiation is broadside directed at the first three bands, tilted at the fourth and split at the fifth band. The resonant frequencies

Article Frontmatter was published on March 1, 2021 in the journal Frequenz (volume 75, issue 3-4).

A novel printed and compact profile monopole antenna with hybrid reconfigurability structure for switching the resonant frequency and direction of maximum radiations is proposed in this research work. A novel mathematical model for the architecture of Reconfigurable Patch Antenna (RPA), considering input impedance, bandwidth, antenna gain, antenna efficiency and resonant frequency is proposed. For

In this article, the design of a radiation beam-reconfigurable antenna using the reflector pins is presented. The reflector pins make a short or open connection with the ground, via switches and Plated Through Hole (PTH), which helps in controlling radiation characteristics of the proposed antenna. This design contains a simple 3D printed Cylindrical Dielectric Resonator Antenna that is located at

A Triple-band Multiple-Input-Multiple-Output (MIMO) antenna for 5G mobile terminal applications is proposed in this paper. The design comprises four-port/two resonators, each having two concentric circular slot ring radiators etched on a ground plane of size 50 mm ×${\times}$ 50 mm. The antenna is fed by perpendicularly arranged 50 Ω microstrip line feeds on the top layer. Decoupling techniques were

In this paper a coplanar waveguide feed (CPW) monopole antenna backed with artificial magnetic conductor (AMC) structure for efficient radiation has been presented for off-body wearable applications. A split ring resonator (SRR) having thiner and longer lines to produce higher inductance and six splits with smaller gaps for high capacitance have been placed underneath CPW fed monopole to achieve resonance

This paper presents electrical equivalent circuit modelling of various fractal-based UWB antennas. Three different designs have been discussed here as case studies, whose characteristics are diversified in nature. Even the implemented fractal geometries are also unique in nature for these antenna problems. An easy circuit model for each antenna structure is proposed which deciphers the insight device

In this article, broadband gain enhancement of an ultra-wide band (UWB) antenna is achieved by using 4 × 4 array of a wideband negative refractive index (NRI) metamaterial as a reflector layer. A novel shaped metamaterial sized 14.8 × 14.8 mm 2 with double negative (DNG) characteristics in three frequency regions has been fabricated on a flexible FR4 with 0.25 mm thickness. The proposed metamaterial

In this paper, an Archimedean spiral antenna-based biosensor has been proposed for the early detection of breast tumor. By monitoring the variation of S 11 over 1–3.5 GHz frequency range, the proposed scheme can identify the tumor location, as well as distinguish the types of tumor (benign or malignant) based on shapes and dielectric properties contrast. To validate the concept, full wave simulation

In this paper, a methodical approach for the in-situ monitoring of the mechanical wear of electrical conductors is presented. The state of life can be assessed by means of the characteristic attenuation of an applied high-frequency alternating current. The advantages of this approach include its non-destructive nature and the applicability to installed and otherwise inaccessible conductors.

Abstract In this article, Terahertz spherical dielectric resonator antenna (DRA) is mathematically formulated and simulated at 511 THz for LiDAR and retinal photoreceptor applications. Titanate DR element is used at optical design frequency. It is validated with good S11, radiation pattern and 5.6 dBi gain plots using HFSS simulator. Unique mathematical formulation on super directivity and radiated

Abstract This paper presents a novel E armed dipole antenna for System On Chip (SOC) applications in the Sub-THz frequency band. The antenna is printed on a corrugated silicon substrate which suppresses surface waves and provides high efficiency and gain. The corrugated substrate also provides a better impedance matching. The antenna has a simulated gain of 5.4 dBi and 3 dB beam-width of 83.5 degree

Abstract A multi spiral split ring resonator based sensor is proposed for the characterization of the dielectric properties of a water ethanol mixture. The use of a narrowed microstrip line to excite the multi spiral resonator allows enhancement of excitation current and increase the sensitivity of the sensing area. Good agreement will be presented between theoretical and measured electrical parameters

Abstract The performance of a generalized mixed free-space-optical (FSO)/millimeter (mm)-wave radio-frequency (RF) two-hop link model is investigated in this work. The first-hop FSO channel considers the influence of path loss, atmospheric turbulence which is modeled by the gamma–gamma (GG)-distribution, and generalized misalignment errors which incorporate the effects of non-zero boresight errors

Abstract A 3 × 3 slotted circular Electromagnetic Band gap based Metasurface (SCEBG-MS) has been presented in this article, which enhances the performance of a circularly polarized (CP) patch antenna by improving its impedance bandwidth, axial ratio bandwidth and gain. The proposed antenna is having a low profile of 0.065 λ o (λ o is the free-space wavelength at center frequency of 6.16 GHz) with ground

Abstract Compact antennas with robust on-body performance are achieving more interest for wearable sensor nodes. In this paper, a modified aperture coupled multiple input multiple output (MIMO) antenna operating at 2.45 GHz industrial scientific and medical (ISM) band is presented for wearable devices. 8-shaped radiator with L-shaped ground slot is used to miniaturize the antenna dimensions. A dielectric

Abstract In this article, a simple design of stacked radiating system with enhanced gain, impedance bandwidth, and radiation efficiency for mobile base station application is presented. The proposed antenna consists of a driven patch with a semicircular parasitic patch printed on the bottom layer and five parasitic patches printed on the top layer. The driven patch is feed by a co-axial probe and both

Journal Name: Frequenz Volume: 75 Issue: 1-2 Pages: i-iii

Abstract In the present article authors propose the design and analysis of an octagonal shape multiband metamaterial loaded antenna with implementation of hybrid fractal geometry for wireless applications. Multiband features in the antenna structure is realized by applying the slotted and hybrid fractalization of Moore and Koch curve approach in radiating section along with introduction of two metamaterial

Abstract In this paper, the scanning rate (SR) is enhanced for substrate integrated waveguide (SIW) based periodic leaky wave antenna (LWA) with continuous beam scanning. Delay line is inserted in the SIW based periodic LWA to modify the group delay profile which in turn increase the SR of the SIW based periodic LWA. Addition of the delay line enhances the SR of the SIW LWA to approximately three times

Abstract Smartdielectric resonator antenna (DRA) having beam control mechanism is anew area to be explored by antenna researchers. Proposed new geometry DRA has low loss, design flexibility, high efficiency, compact size and desired radiated beam control. Developing beam control in new geometry DRAs is investigated for the first time in this letter. Unique technique for beam control and beam width

Abstract In this paper, a balanced-to-balanced (BTB) branch-slotline directional coupler (DC) is firstly presented, which can realize an arbitrary power division ratios (PDRs). The coupler is composed by microstrip-to-slotline (MS) transition structures and branch-slotline coupled structures. The single-ended to balanced-ended conversion is simplified and easy to implemented by the MS transition structures

Abstract This paper presents a concurrent dual-band radar system for noncontact tracking of vital signs (e.g., respiration and heartbeat), and indoor short-range localization. The proposed sensor, which has been achieved with our own customized concurrent dual-band subsystems, operates at 1.67 and 2.06 GHz synchronously. Based on the Doppler principle, tiny vital signs are obtained by analysis of spectrum

Abstract In this paper the design and analysis of two dimensional photonic crystals based all optical AND logic gate is investigated. A logic gate implements a Boolean function and thus performs a logical operation on one or several logic inputs in order to produce a single logic input. The proposed all optical AND gate is designed with line and point defect using a hexagonal lattice with “Y” shaped

Abstract In this paper, a novel technique based on transmission-only measurements is proposed to determine complex permittivity and permeability of low-loss materials. The proposed method removes the influences of the sample thickness and avoids the resonances in the extracted parameters. Both the experiment and simulation are applied to present the advantages of the proposed method. Compared with

Abstract In this paper, a novel approach to achieve multiband antenna operation using metamaterial based resonant structures is presented. Multiband antenna operation is achieved by employment of complementary split ring resonators (CSRR) printed in the ground plane. The CSRRs resonate at different frequencies according to their optimized dimensions. Proposed approach features simple design and fabrication

Journal Name: Frequenz Volume: 74 Issue: 11-12 Pages: i-iii

Abstract The all-optical logic gates have become an important key enabling in optical integrated circuits and find applications in optical networks. In this paper, we introduce new complete series of optical logic gates using photonic crystals. These designs formed by compilation with interference based defect and resonance phenomenon. The proposed work based on two dimensional square lattices by putting

Abstract A low profile Circular Microstrip Patch Antenna (CMPA) with radius 5 mm has been designed to generate two resonant frequency bands that can be used for WLAN 5.2 (5.15–5.25) GHz, Wi-Fi (5.725–5.850) GHz and Dedicated Short-Range Communications (DSRC) (5.85–5.925) GHz application bands. The designed antenna has been slitted with two slits and a stub has also been attached resulting in an additional

Abstract Miniaturizing the microwave circuits for micro-satellite platform has been one of the development trends in microwave remote sensing. A novel 89/118/166/183 GHz frequency dividing network is proposed in this paper which includes two stages: the first stage is an F-G band diplexer that separate 89/118 GHz signals from 166/183 GHz signals. The measured typical transmission loss is 1.5 dB from

Abstract In this paper a wideband, flexible, and novel structured double negative (DNG) metamaterial is designed for S, C, X, and Ku microwave applications. The 12 mm × 12 mm sized metamaterial is fabricated on a flexible FR4 substrate with thickness 0.25 mm. The metamaterial shows a total wide DNG region of 8.2 GHz (3.8–4.3 GHz and 6.8–14.5 GHz). The transmission coefficient of the unit cell has a

Abstract In this paper, we study the optimization of two tilt angles corresponding to two antenna arrays in each base station (BS) of a massive multiple-input multiple-output system. We consider two scenarios with perfect channel state information (CSI) and imperfect CSI. In the limit of the number of the BS antennas, the channel orthogonality is employed to derive the limit and the lower bound of

Abstract In this paper a Quad-band diversity antenna with a small size of 48 × 28 × 0.8 mm3 printed on FR4 substrate is presented that consists of two same pentagonal-shaped patch elements. Four arc-shaped slots in the radiating elements are introduced to obtain the quad-band operation with good return loss. The antenna is designed for covering 5.91 GHz in IEEE 802.11 b/g/n standards, 7.40 GHz in C-Band

Abstract In this study, estimation of Ultra-Wideband (UWB) characteristics of microstrip elliptic patch antenna is investigated by means of k-nearest neighborhood algorithm. A total of 16,940 antennas are simulated by changing antenna dimensions and substrate material. Antennas are examined by observing Return Loss and Voltage Standing Wave Ratio (VSWR) characteristics. In the study, classification

Abstract In this paper, parallel coupled meander lines (PCML) composite right/left-handed transmission line (CRLH-TL) based symmetrical quasi-0 dB coupled-line coupler is presented. Proposed coupler shows measured backward wave coupling level of 0.81 dB at frequency of 6.17 GHz with 3 dB fractional bandwidth (FBW) of 12.64%. Throughout the 3 dB frequency range (5.78–6.56 GHz), isolation and insertion

Journal Name: Frequenz Volume: 74 Issue: 9-10 Pages: i-iii

Abstract This research proposes a novel circularly polarized (CP) reconfigurable microstrip loop antenna for 2.4–2.5 GHz advanced wireless communication using two parasitic patches and two PIN diodes. The reconfigurable antenna can alternate between right hand circular polarization (RHCP) and left hand circular polarization (LHCP) at the main beam by manipulating the ON/OFF status of the PIN diodes

Abstract In this paper, a tunable balanced-to-balanced in-phase filtering power divider (FPD) is designed, which can realize a two-way equal power division with high selectivity and isolation. A differential-mode (DM) passband with a steep filtering performance is realized by applying microstrip stub-loaded resonators (SLRs). Meanwhile, six varactors are loaded to the SLRs to achieve the center frequency

Abstract In this paper, a novel tri-band reconfigurable patch antenna with simple structure is presented. By changing the on-off state of only two PIN diodes, the antenna can operate in three bands, namely X-band, Ku-band, and Ka-band. The overall size of the antenna is 0.24λ L × 0.5λ L × 0.019λ L , where λ L is the free-space wavelength of the lowest operating frequency. A prototype is fabricated