Feed Line Research Articles

A Novel Balanced Nonreciprocal Bandpass Filter Based on Stub‐Loaded Ring Time‐Modulated Resonator

ABSTRACTIn this paper, a novel balanced nonreciprocal bandpass filter based on stub‐loaded ring time‐modulated resonators (TMRs) is proposed, which is co‐designed to integrate the feed circuits and common‐mode (CM) suppression circuits. The design employs the fewest TMRs necessary, which is at least two, to achieve a reverse isolation level of larger than 20 dB. This configuration also ensures the presence of two reverse isolation poles, thereby maximizing the reverse isolation bandwidth. Even‐ and odd‐mode analysis elucidates the isolation of signals under differential mode (DM) and the suppression of noise under common mode. This approach eliminates the need for separate feed lines and complex CM noise suppression circuit designs. Furthermore, parameterization analysis is adopted to verify the modulation parameters on the impact of the circuit. A balanced microstrip nonreciprocal bandpass filter, centered at 1.5 GHz, has been designed, simulated, and experimentally verified. The measured DM forward insertion loss is 3.9 dB, and the reverse isolation is greater than 20 dB with a bandwidth of 48 MHz. The measured CM noise suppression exceeds 26.6 dB within the frequency range of 1.2 to 1.8 GHz.

A Four Element UWB MIMO Antenna with Band - Notched Characteristics for Wireless Communication Applications

Abstract: This study proposes an innovative approach to enhance isolation in a four-element Ultra Wide Band (UWB) range Multiple Input Multiple Output (MIMO) antenna system. The design employs unique rhombic and cross-shaped slot structures to achieve compactness, with dimensions of 34 mm × 34 mm × 1.6 mm. To minimize mutual coupling, the antenna incorporates orthogonally placed feed lines alongside a parasitic strip measuring 17 mm × 1 mm × 1.6 mm. The antenna effectively suppresses interference from specific bands, including WiMAX, WLAN, and X-band, through the integration of L-shaped and Cshaped slits combined with Electromagnetic Band Gap (EBG) elements. Simulation results, verified through practical testing, confirm an operational bandwidth 2 GHz to 12 GHz, excluding the targeted notched bands. The design achieves superior isolation (S11 < -10 dB), a peak gain of 2.5–5 dB, and excellent interference rejection capabilities. These features establish the antenna as a highly efficient option for next-generation UWB-MIMO wireless communication applications.

Resonance frequency prediction of dielectric antennas for liquid sensing via support vector regression

This paper presents a slot antenna integrated with a split ring resonator (SRR) and feed line, designed to achieve a high Q-factor while maximizing channel capacity utilization. By incorporating a lens into the dielectric resonator antenna (DRA), we enhance both bandwidth and directivity, with the dielectric material’s permittivity serving as a key control parameter for radiation characteristics. We explore water and ethanol as controllable dielectrics within the terahertz (THz) frequency range (0.5-1 THz), implementing these liquids through microfluidic techniques. This novel design serves two purposes, functioning as both an antenna system and a highly sensitive material sensing device. The antenna’s performance is evaluated using the Debye model for pure water and ethanol, with electromagnetic full-wave simulations employing the Finite Integration Technique (FIT) to model both the antenna and microchannel structures. For predicting resonant frequencies based on antenna dimensions, we implement a Support Vector Regression (SVR) algorithm, comparing its performance against various models including Linear Regression, Regression Trees, Ensemble Bagged Trees, Ensemble Boosted Trees, and Three-layered Neural Network Models. The SVR demonstrates superior prediction accuracy by effectively capturing non-linear relationships between antenna dimensions and resonant frequencies.

Constructing a Microstrip Phase Shifter with Low Phase Error Using a Y-Resonator

In this paper, we propose a Y-type dual-mode microstrip phase shifter that utilizes input–output cross-coupling. The structure comprises a main line and a reference line, with the main line designed in a cross-coupled parallel-feeding configuration to create a band-pass filter. The single-mode resonance frequency is fine-tuned to meet the bandwidth requirements of the band-pass filter. Additionally, by introducing new symmetric transmission zeros in the upper and lower cutoff bands through the cross-coupling of the input and output feed lines, we achieve a quasi-elliptic response. This design significantly enhances both the passband and out-of-band performance of the filter. The reference line functions as a uniform transmission line, and the phase shift value of the phase shifter is achieved by adjusting its electrical length. Compared to conventional phase shifters, this design offers several advantages, including a simpler structure, reduced phase error, and a wider phase shift range. Ultimately, a 90° to 225° phase shifter was designed and simulated, while a 90° phase shifter was fabricated and tested. Measurement results indicate that the designed phase shifter successfully achieves a phase shift of 90° ± 1.2°, with S11 less than 16.5 dB and a fractional bandwidth (FBW) of 60.8%.

Synthesis and Characterization of the Microwave Dielectric Properties of a (1-x) Li<sub>3</sub>MgNbO<sub>5</sub>–(x) Sr<sub>3</sub>V<sub>2</sub>O<sub>8</sub> Composite for Antenna Application

This study investigates the fabrication of a cylindrical dielectric resonator antenna (CDRA) using ceramic microwave dielectric composites as a resonator. The composites (1-x) Li3MgNbO5-(x) Sr3V2O8 (x=0.25-0.40) have been synthesized via the conventional solid-state reaction method, incorporating 1% B2O3 to lower the sintering temperature. The 0.70-0.30 composite exhibited optimal microwave dielectric properties with a dielectric constant (εr) of 19.20, a quality factor (Q x f) of 3738 GHz, and a temperature coefficient (τf)of -43 ppm/°C. These characteristics render the 0.70-0.30 composite suitable for CDRA applications. The experimentally obtained microwave dielectric parameters were used to simulate the CDRA design using the High-Frequency Structure Simulator design software. A single-feed cylindrical antenna has been fabricated using this composite material as a resonator with a radius × height of 5×6 mm2, mounted on an FR4 substrate measuring close to 25×25×1.6 mm3 and Cu strip as a feed line. The simulated and experimentally measured parameters, including S11, voltage standing wave ratio, and radiation pattern, demonstrated excellent agreement, validating the composite's efficacy for antenna design.

Synthetic Imaging Radar Data Generation in Various Clutter Environments Using Novel UWB Log-Periodic Antenna.

In short-range microwave imaging, the collection of data in real environments for the purpose of developing techniques for target detection is very cumbersome. Simultaneously, to develop effective and efficient AI/ML-based techniques for target detection, a sufficiently large dataset is required. Therefore, to complement labor-intensive and tedious experimental data collected in a real cluttered environment, synthetic data generation via cost-efficient electromagnetic wave propagation simulations is explored in this article. To obtain realistic synthetic data, a 3-D model of an antenna, instead of a point source, is used to include the coupling effects between the antenna and the environment. A novel printed scalable ultra-wide band (UWB) log-periodic antenna with a tapered feed line is designed and incorporated in simulation models. The proposed antenna has a highly directional radiation pattern with considerable high gain (more than 6 dBi) on the entire bandwidth. Synthetic data are generated for two different applications, namely through-the-wall imaging (TWI) and through-the-foliage imaging (TFI). After the generation of synthetic data, clutter removal techniques are also explored, and results are analyzed in different scenarios. Post-analysis shows evidence that the proposed UWB log-periodic antenna-based synthetic imagery is suitable for use as an alternative dataset for TWI and TFI application development, especially in training machine learning models.

Assessing Grid Reliability for Optimal Integration of System-Integrated Modular Advanced Reactor Technology (SMART) for Kenya: A Case of the Nairobi Distribution Network

The integration of advanced nuclear technologies like the System-Integrated Modular Advanced Reactor (SMART) offers a transformative approach to enhancing grid reliability in developing countries. This study focuses on the Nairobi distribution network in Kenya, a critical region characterized by an evolving energy mix of geothermal, hydro, solar, and wind power sources, comprising 220 kV and 132 kV transmission lines feeding 66 kV, 33 kV, and 11 kV distribution lines to various load centers. Using ETAP 22 simulation software, the research evaluates the impact of SMART integration through three scenarios: baseline operation, grid compensator-only operation, and SMART-SMR integration. Key reliability indices such as the System Average Interruption Frequency Index (SAIFI), System Average Interruption Duration Index (SAIDI), and Expected Energy Not Supplied (EENS) were analyzed. Results reveal that integrating a 100 MW SMART reactor reduces SAIDI by 2.8% (5.0433 h/customer-year) and SAIFI by 5.1% (0.0516 interruptions/customer-year), while maintaining voltage profiles within 98.21–98.91% of nominal. This analysis bridges gaps in prior research by demonstrating SMART’s ability to stabilize power grids in emerging economies, providing critical insights for policymakers aiming to achieve reliable and sustainable energy systems.

Design and analysis of dual-band circularly polarized coplanar waveguide antenna for millimeter-wave 5 G applications

Abstract A dual-band circularly polarized antenna has been designed for millimeter-wave applications, operating over the frequency ranges of 27 GHz to 28.45 GHz and 34.3 GHz to 35.8 GHz. The proposed coplanar waveguide (CPW) antenna features a central feed line serving as the main signal conductor, with circular structures arrayed around it acting as radiating elements. These elements are strategically designed for optimal performance at millimeter-wave frequencies. The antenna, with physical dimensions of 8 mm × 7 mm × 0.757 mm, corresponds to approximately 0.72λ × 0.63λ × 0.068λ at 27 GHz, where λ represents the free-space wavelength. Fabricated on a Rogers RT/duroid 5880 substrate, the antenna’s practical measurements exhibit good agreement with simulated results. The antenna achieves an overall gain of up to 6 dBi across the operating bandwidth, maintaining an axial ratio of less than 3 dB. These results confirm the antenna’s efficacy, making it a superior choice for millimeter-wave 5 G applications.

INVESTIGATION OF THE EFFECTS OF DIFFERENT FEED LINE STRUCTURES ON UWB ANTENNA PERFORMANCE BY CHARACTERISTIC MODE ANALYSIS

This study investigates the effect of various feed topologies on the parameters of a novel ultra-wideband (UWB) antenna using characteristic mode analysis. The proposed design is guided by characteristic mode analysis, commencing with a basic square structure. Initially, a closed-form estimate of the resonance frequencies of the primary modes is provided for the square-shaped structure. Subsequently, the characteristic modes that resonate in the frequency spectrum are modified by introducing symmetrical square slots. To excite these modes and achieve a wideband antenna that encompasses the relevant spectrum, the geometry of the feeding line is altered and its effects are examined. The study incorporates two fundamental feed line geometries: tapered and traditional feed impedance lines. The proposed UWB antennas are fabricated and measured to validate their performance. According to the measurement results a wide impedance bandwidth of 147.82% at -10 dB reference ((0.9–6 GHz)) and stationary radiation patterns across the operating frequency band are obtained for the tapered feed line. The results demonstrate a significant advantage of the tapered feed line over the traditional impedance line. The results for the fabricated prototypes exhibit high similarity to the simulated results. The findings confirm the applicability of the mode analysis method.

Leaf-Shaped Nanostrip Fed Graphene Plasmonic Nano-Antenna for Optical Near-Field Applications

The manuscript investigates the leaf-shaped nanostrip-fed graphene plasmonic nanopatch on a silicon dioxide surface for optical near-field applications. The dispersion properties of graphene and silicon dioxide are demonstrated through Drude and Lorentz modeling to examine the suitability of the materials for the plasmonic nano-antenna design. The nano-antenna parameters TSUB (substrate thickness), W (width of the nanostrip feed line) and RL(nano-antenna size) are adjusted to modify the plasmonic resonance frequency from 7.9 THz to 40.9 THz. The proposed leaf-shaped nanostrip-fed graphene plasmonic nanopatch exhibits a reflection of -43.27 dB at 36 THz with a gain of 8.19 dB at TSUB =125 nm, W = 40 nm and RL = 50 nm.

Wideband star-shaped antenna based on artificial magnetic conductor surface for unidirectional radiation

Gathering the advantages of low profile, high gain, high efficiency, and wideband operation in a planar antenna is a challenging objective for the antenna designer. Low profile wideband antennas are usually characterized by low gain. An antenna of wideband impedance matching usually suffers continuous variations of the gain over such a wideband due to the variation of the radiation mechanisms and surface current distributions over the frequency band of impedance matching. Therefore, the motivation of the present work is to provide both impedance matching and stabilized high gain by the aid of wideband artificial magnetic conductor (AMC) with a design of the unit cell that is suitable to the antenna structure and the desired frequency band. The present work, proposes the utilization of low-size wideband AMS surface (AMCS) to be placed behind a wideband omnidirectional antenna to enhance the gain over the frequency band of operation. In this way, the radiating structure combines high gain and wideband operation in the same design. A wideband planar monopole printed antenna is designed to operate as omnidirectional antenna with perfect impedance matching and radiation efficiency over the frequency band 3.6-7.2GHz when placed in free space. The gain of the free-standing antenna varies from 2dBi to 4.5dBi over the frequency band. A wideband AMCS is designed to enhance the antenna gain over frequency band of operation. The designed AMCS is composed of only 3×3 unit cells and overall dimensions of 10×10cm. This surface is placed parallel to the planar antenna at a distance 1.7cm behind it. The enhanced gain of the radiating structure of the AMCS-backed antenna reaches 8.5dBi without affecting the bandwidth over which the input impedance is matched to the feeding line. The radiation efficiency of the AMCS-backed antenna is maintained above 98% over the frequency band of operation (3.7-7.2GHz). The wideband antenna and the AMCS are fabricated for practical evaluation of the overall AMCS-backed antenna performance including the measurements of impedance matching, gain and radiation efficiency. The measurements and simulation results are in good consent.

Substrate integrated waveguide differential antenna for full duplex applications

Abstract This paper presents a substrate-integrated waveguide (SIW) differential antenna for full duplex applications. The proposed antenna consists of two square SIW cavities named as outer and inner. The inner cavity is nested into the outer cavity. The outer cavity is differentially excited with a pair of coaxial feed lines, while the inner square patch is orthogonally excited with another pair of differential coaxial feed lines. This orthogonal feeding arrangement results in high isolation between the differential ports. The modified hybrid TE130/310 mode of the outer cavity radiates through a pair of arc-shaped slots at 9.35 GHz, while the TM01 mode of the inner square patch is responsible for the radiations at 8.65 GHz. The proposed antenna prototype is fabricated and measured for validation. Moreover, the designed antenna has a front-to-back ratio better than 22 dB and measured maximum gain values of 6.1 dBi and 7.6 dBi at 8.65 GHz (Port 2 ON) and 9.35 GHz (Port 1 ON), respectively.

Four-mode frequency reconfigurable antenna for 28 GHZ and 38 GHZ communication

This paper presents a four-mode frequency reconfigurable antenna design for 5G communication systems. The patch antenna approach has been chosen in the design steps and the proposed antenna contains two adjacent patches for corresponding operating frequencies. PIN diodes were located in the feeding line of each patch element to control the on or off state. There are four modes, which are OFF/OFF, OFF/ON, ON/OFF, and ON/ON modes, that correspond to no resonance, resonance at 38 GHz with −25 dB, resonance at 28 GHz with −16 dB and resonance at around 35.3 GHz with −22 dB, respectively. This approach paves the way for controlling the resonance point of an antenna element for 5G applications with high accuracy. The proposed antenna structure was fabricated and experimentally measured in a microwave laboratory to show the feasibility of the proposed idea, and the obtained experimental results are in good agreement with the numerical results.

Design of folded dipole antenna with stub feed line at 3.5 Ghz operating frequency for 5G cellular network

Design of folded dipole antenna with stub feed line at 3.5 Ghz operating frequency for 5G cellular network

Design and Analysis of Microstrip Line Fed Gap Coupled Triple Band Slotted Patch Antenna for WiMAX, WLAN, and Sub‐6 GHz 5G Applications

ABSTRACTThis paper presents a gap coupled triple band slot loaded microstrip patch antenna with parasitic patches. It consist inverted U‐shape and inverted T‐shape open‐ended slots along with a rectangular slot at center of patch. The inverted U‐shape open‐ended slot generates a driven patch at bottom side and an inverted U‐shape parasitic patch at middle side of patch while inverted T‐shape open‐ended slot generates two rectangular shape parasitic patches of same dimension at top side of patch. The proposed gap coupled antenna covers 2.29 to 2.77 GHz in first band, 3.25 to 3.65 GHz in second band and 4.67 to 5.72 GHz in third band with return losses of −23.2, −19.90, and −38.06 dB, respectively. The proposed antenna resonates at 2.57, 3.48, and 5.37 GHz with fractional bandwidth of 18.97% (480 MHz), 11.59% (400 MHz), and 20.21% (1050 MHz), respectively. The return loss and bandwidth of presented antenna is increases gradually by loading inverted U‐shape and inverted T‐shape open‐ended slots along with a rectangular slot in antenna patch. The proposed antenna exhibits stable peak gain of 4.45, 4.81, and 5.26 dBi and efficiency of 89.5%, 89%, and 90% in three resonating bands. The antenna resonating bands are applicable for WiMAX: 2.5/3.5/5.5 GHz (2.5–2.69, 3.4–3.69, and 5.25–5.85 GHz), WLAN: 2.4/5.2 GHz (2.4–2.484 and 5.15–5.35 GHz) and sub‐6 GHz 5G: 3.5 GHz (3.3–3.8 GHz). The size of antenna is 40 mm × 50 mm (0.34 × at frequency 2.57 GHz). The gap coupled antenna geometry is fed by microstrip line feed and simulated by IE3D simulation tool.

Response study of impact of slot area variation in miniature antenna for Kurtz-Above band applications in 5G/6G wireless communication

Modern fifth-generation/sixth generation (5G/6G) wireless demand for efficient miniature antenna. To fulfill these demands here efforts have been made using high frequency structure simulator software (HFSS) to design a compact microstrip patch antenna (MPA). The design of the antenna consisted of two slots- one located near the feed line and the other one at the opposite side of the feed line. The volumetric dimension of the proposed antenna was 13.2 mm x 11.4 mm x 1.6 mm, designed at resonant frequency 33 GHz, employing 1.6 mm thick Rogers RT Duroid 5880 substrate having dielectric constant 2.2 and loss tangent 0.0013. A transmission line having a length of 5.7 mm and a width of 2 mm was used to excite the antenna for electromagnetic radiation fields. Antenna parameters simulation results were obtained for different slot areas, keeping other design parameters like dimensions of ground, patch, substrate, and feed port fixed. Different slot areas were selected by changing slot width, keeping its length constant. A gain of 7.7 dB with voltage standing wave ratio (VSWR) of 1.9 and return loss (S11) -19.23 dB was obtained for slot width 3 mm and area 1.5 mm2. The directivity of the antenna was reported as 5.7dB, with a very good surface current density of 104.94 Amp/m, considered sufficient in the fringing fields breaking situation. Bandwidth was found to be inversely proportional to slot width. VSWR, S11, and 3D gain showed inverse dependence on slot area. Gain and S11 change in direct proportion to feed width whereas VSWR changes inversely with feed length. The proposed MPA is suitable for satellites, mobile phones, wireless communication systems, and remote sensing applications.

The Experience Using of Freeze-Dried Mulberry Leafs’ as Composition of Artificial Diet for Feeding Silkworm Caterpillars

Aims: Due to changes in the global climate and the recent increase in spring frosts, which lead to the death of silkworm caterpillars of the first ages due to lack of food, there is an urgent need to find effective and cheap means to replace natural food - mulberry leaf. One of the promising methods is the preservation of mulberry leaf. One of the new and progressive methods of preservation is the method of freeze-dried of mulberry leaf, for the basis of artificial diet. Place and Duration of Study: The experiments were conducted in the laboratory of the Scientific Research Institute of Sericulture in 2024y. Methodology: After hatching, the caterpillars were fed artificial food based on freeze-dried mulberry leaf, the food was given once a day, the room temperature was 25-26 ° C, humidity 65-70%. When the caterpillars reached the third age, some of the caterpillars of each breed and hybrid were selected and continued to be fed with artificial diet. The remaining caterpillars were transferred to natural leaf feeding according to a generally accepted method. Results: The drying time of the mulberry leaf in the freeze-dried mode was 14-18 hours, depending on the uniformity of the leaf layer in the chamber. A recipe for artificial diet was created, in which the content of mulberry leaf powder was 72%. All breeds and hybrids equally well received the developed artificial diet. In breeds and hybrids, the viability of caterpillars was 82-100%. And when switching from artificial diet to a natural leaf, the viability of caterpillars was 63-93%. Conclusion: All breeds and hybrids equally well accepted the developed artificial food based on freeze-dried mulberry leaf. According to the totality of the results shown, the studied breeds and hybrids are promising for feeding them on artificial feed and breeding appropriate lines and breeds from them.

Beyond viability: Advancing CHO cell culture process strategies to modulate host cell protein levels

Chinese Hamster Ovary (CHO) cells are widely utilized in bioprocessing industry for monoclonal antibody (mAb) production. In many instances, challenges persist in achieving sufficient clearance of Host Cell Proteins (HCPs) in the final drug substance. While purification strategies usually offer substantial HCP clearance, certain "problematic" HCPs, particularly lipases, continue to pose significant challenges. This study investigates the accumulation of various "problematic" HCPs in CHO cell culture using transcriptomics, revealing correations between cell culture parameters and HCP level. Contrary to conventional assumptions, viability alone does not reliably predict HCP levels, with factors such as clone selection, host cell line choice, media and feed compositions significantly influencing HCP accumulation. Leveraging transcriptomics-based approaches, we demonstrate the potential of upstream process control strategies to mitigate HCP presence and improve biologic product quality. Our findings underscore the importance of considering diverse cell culture parameters in bioprocess optimization to ensure product stability and quality. While promising, further research is needed to elucidate the mechanisms underlying HCP release and propagation through downstream processing stages, emphasizing the necessity of a comprehensive integrated approach to HCP control in biologics production.

Part Feeding and Internal Transportation Decision Making for a Machinery Manufacturer

This research validates a mixed integer linear programming model that minimizes total feeding and acquisition costs by integrating assembly line feeding and vehicle type decisions in a machinery manufacturing company. The results show that the optimal assignment reduces costs by 56% compared with the company's current assignment.

A compact wideband filtering rectangular dielectric resonator antenna with U-shaped metal strips

ABSTRACT In this paper, a compact wideband filtering rectangular dielectric resonator antenna (RDRA) loaded with a pair of U-shaped metal strips is proposed. By using a slot-coupled feeding structure, a rectangular DR with a length–width ratio of 3:1 is selected to combine the resonant frequencies of the TE 111 and TE 121 modes to achieve the passband. Two pairs of transverse branches with different lengths are added to the longitudinal microstrip feeding line, and the TE 111 , TE 11+δ1 , and TE 121 modes are successfully excited to enhance the bandwidth. The short pair of transverse branches can generate a null high-frequency radiation. A pair of U-shaped metal strips is loaded at both ends of the top of rectangular DR, introducing a low-frequency radiation null. Both radiation nulls can be independently adjusted. A pair of rectangular grooves is etched inside rectangular DR to boost the impedance matching level. The proposed filtering RDRA has been fabricated and measured for verification. The measured relative impedance bandwidth is 22.67% (4.34–5.45 GHz). The measured average gain and peak gain are 7.19 dBi and 8.06 dBi, respectively. RDRA filtering has broad application potential in modern communications, such as the N79 band.