Slot Line Research Articles

Design and Modelling of a Modified High Gain Printed Vivaldi Antenna for EMC Measurements

This paper demonstrates the design, modeling, and analysis of a small size 180 × 165 × 1.6 mm3 printed broadband Vivaldi antenna for electromagnetic compatibility measurements. The proposed antenna is intended to be utilized as a reference antenna for emission and immunity tests inside the EMC Chamber through the band (0.8–5.5 GHz). Exponentially tapered slots were created based on mathematical equations to form an end-fire radiation antenna. Furthermore, microstrip and slot line stubs were employed to tune the impedance bandwidth. This antenna could be considered a 2-D Horn antenna with a size reduction of 64% and 67% since both antennas, Vivaldi and Horn are based on the same principle. Two rectangular slots were engraved near the feeding point to reshape and enhance the gain at lower frequency bands. Furthermore, the realized gain has been improved by approximately 3.5 dB and reached up to 10.7 dBi by introducing a pair of triangular reversal slots at the top edges of the structure. Moreover, this antenna has specifications that make it a suitable candidate to work as a reference antenna inside the EMC chamber compared to the classical Horn antenna offered for sale (PowerLOG® PRO 30800 and TBMA4).

A 3-D Wideband and High-Selectivity Amplifying Frequency-Selective Surface Based on Slot Line and Microstrip Line

A 3-D Wideband and High-Selectivity Amplifying Frequency-Selective Surface Based on Slot Line and Microstrip Line

Design of a compact filtering antenna with multi-adjustable radiation nulls

ABSTRACT A compact filtering antenna with multi-adjustable radiation nulls is designed. Initially, a conventional aperture-coupled antenna is crafted by fine-tuning positions of the gap and radiation patch, achieving a radiation null. Additionally, an aperture-coupled filtering antenna is created by cascading a resonator with a microstrip feedline. Subsequently, the integration of the aperture-coupled antenna and the filtering antenna results in a dual-slot aperture cross-coupling filtering antenna, with two radiation nulls at both ends of the passband. Finally, a pair of slot lines is etched on the radiation patch, introducing an extra radiation null to enhance selectivity further. The measured results show that the proposed filtering antenna has a bandwidth from 2.44 to 2.64 GHz for |S 11|<−10 dB, a peak gain of 5.5 dBi, and three radiation nulls at 2.3, 2.75, and 3.15 GHz enhancing the selectivity.

Phase delay through slot-line beam switching microstrip patch array antenna design for sub-6 GHz 5G band applications

Two, four, eight, and sixteen-element patch array antennas for beam switching are presented in this study. For a 1×2 array, an aperture-coupled feeding mechanism is used to feed patches while a slot line on the ground plane provides the phase delay between antenna elements. The 1×2 array is used to create the 2×2, 4×2, and 8×2 arrays, and an equal power divider provides the signal for each. For applications in the 5G sub-6 GHz frequency spectrum, the antennas are modeled. With -37.14 dB, -17.85 dB, -21.51 dB, and -26.03 dB return loss for two, four, eight, and sixteen-element array antennas respectively the simulation demonstrates that the antennas are properly matched at the resonant frequency. The antennas can switch its radiated beam to ±24&lt;sup&gt;o&lt;/sup&gt;, ±24&lt;sup&gt;o&lt;/sup&gt;, ±28&lt;sup&gt;o&lt;/sup&gt;, and ±26&lt;sup&gt;o&lt;/sup&gt; with gains of 8.97 dBi, 11.19 dBi, 13.23 dBi, and 16.24 dBi, respectively at the resonance frequency. The directivity of the proposed antenna is found to be 9.17 dBi, 11.20 dBi, 13.40 dBi, and 16.45 dBi respectively. The antennas are constructed with two 0.8 mm-thick Teflon substrate layers. The ground plane between the two substrate layers contains the aperture and the slot line that generates the phase delay.

A simple feed orthogonal excitation X-band dual circular polarized microstrip patch array antenna

This work represents a microstrip patch array antenna which is designed and analyzed for the application of circular polarization in X band frequency range. The proposed antenna array has a very simple microstrip line feeding mechanism and each patch is energized orthogonally to acquire circular polarization without the need for any phase shifters. The array antenna has a slot line in the ground to electrically couple the signals from the microstrip feed line to feed each patch. The outcome demonstrates that the antenna is capable of radiating both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The designed work has a return loss of -41.88 dB, that is the antenna is perfectly matched. The outcome also demonstrates the antenna’s strong gain and directivity capabilities, which are 12.87 dBi and 13.30 dBi, respectively. The antenna resonates circularly at a frequency of 10 GHz.

A 5G beam-steering microstrip array antenna using both-sided microwave integrated circuit technology

In this paper a beam steering 2×2 microstrip array antenna is proposed and simulated for the 5G sub-6 GHz frequency band. The array antenna is designed at the resonant frequency of 3.5 GHz. The antenna has four patches excited by two microstrip lines. Microstrip lines on top of teflon substrate of 0.8 mm height and slot line in the ground plane makes a hybrid junction. The design uses both sided microwave integrated circuit (MIC) to feed signal to the patch elements. This designed array antenna has the beam steering capability of maximum -17º to +17º while keeping the side lobe gain below 10 dB. The simulation results show that the array antenna is designed through good input impedance matching. The antenna has a return loss of -43 dB at center frequency 3.5 GHz. The results also show that the array antenna has a high gain of 12.57 dBi and directivity of 25.11 dB. The maximum gain of this antenna is 24.1 dB at -17º and +17º. The proposed work is simulated on keysight technologies advanced designed system (ADS).

In silico, in vitro, and in vivo validation of a microwave imaging system using a low‐profile Ultra Wide Band Archimedean spiral antenna to detect skin cancer

AbstractMicrowave imaging (MI) is a noninvasive and nonionizing procedure for detection of cancerous cells in healthy body tissues using radiofrequency (RF) and microwaves. The procedure involves the use of Ultra Wide Band (UWB) antennas for sensing purposes. Therefore, this research article presents the design, development, and testing of a low‐profile UWB Archimedean spiral microstrip‐patch antenna (ASMA) for detection of skin cancer using monostatic radar‐based microwave imaging. The proposed ASMA consists of a spiral resonator with a defective ground structure and a slotted microstrip feed line with dimensions of 38 × 38 × 0.87 mm3. The proposed antenna shows an impedance bandwidth for the frequency range of 2.2–13.9 GHz, with a peak gain of 6.8 dB at 7.8 GHz. In silico analysis of the proposed ASMA for MI is carried out with Gaustav model using Computer Simulation Technology Microwave Studio. To validate the performance of the ASMA as a sensor for MI, a prototype of the same is fabricated and a four‐layered bio‐phantom of the human forearm is prepared for in vitro and in vivo testing of the proposed procedure. The validation of ASMA radiation properties is done using a Vector Network Analyser (E‐5063A) (VNA) and an anechoic chamber with the fabricated antenna at 10 mm away from the prepared bio‐phantom. The recorded S parameter data with bio‐phantom and the VNA is processed using different beamforming algorithms like Delay and Sum and Coherent Factor‐Delay Multiply and Sum (CF‐DMAS) to reconstruct the image of the scanned area. The reconstructed images are 97%–98% accurate. The proposed ASMA sensor is also safe for human exposure as it has a specific absorption rate of 0.0546 W/Kg at 5 GHz that complies with the safety guidelines of the Federal Communications Commission to minimize potential health risks associated with exposure to RF and microwave radiation.

Compact Dual-band BPF Based on Loaded SIW with Meandered Slot Line for 5G and Beyond Applications

Compact Dual-band BPF Based on Loaded SIW with Meandered Slot Line for 5G and Beyond Applications

Investigation of characteristics of a slot line with the slot shift to the edge of dielectric substrate

Investigation of characteristics of a slot line with the slot shift to the edge of dielectric substrate

Broadband Linear Polarization Converter Based on Slot-Line Loaded Structure for Pre-Determined Notched Band

This brief proposes a broadband linear polarization converter with pre-determined notched band. By loading a H-shaped slot line on the basis of the rectangular resonator, a pair of resonator modes as well as pre-determined polarization conversion zeros can be additionally allocated inside the band, thereby realizing broadband and band-notch characteristics, simultaneously. The multi-mode resonant mechanism to realize broadband and the conversion zero control principle for notched band are analyzed in detail. Finally, a notch-band broadband linear polarization converter is designed and fabricated, and the simulated and measured results are agreed well with each other. As the main advantage, the proposed multi-mode resonant structure realizing the notched band can achieve flexible isolation band design while hardly affecting the broadband filtering characteristics, and is especially suitable for pre-determined spectrum windows of broadband electromagnetic control devices.

A New SIDGS-Based Tunable BPF Design Method with Controllable Bandwidth

This paper provides a new method to implement substrate integrated defected ground structure (SIDGS)-based bandpass filter (BPF) with adjustable frequency and controllable bandwidth. Compared with previous literature, this method implements a new SIDGS-like resonator capable of tunable frequency in the same plane as the slotted line using a varactor diode, increasing the design flexibility. In addition, the method solves the problem that the tunable BPF constituted by the SIDGS resonator cannot control the bandwidth by introducing a T-shaped non-resonant unit. The theoretical design method and the structural design are shown. Moreover, the configured structure is fabricated and measured to show the validity of the design method in this paper.

Microstrip to Slot-Line-Fed Microstrip Patch Antenna with Radiation Pattern Diversity for X-Band Application

This paper proposes a planar wideband microstrip feedline to a slot-line-based patch antenna for high-frequency pattern diversity applications. The antenna consists of two adjacent rectangular patches separated by the ground slots, with a directive patch slot along the edge of the substrate. A compact common feedline-to-slot configuration is used to miniaturize the antenna. The antenna is designed in stages, starting with an in-phase feedline, followed by a slot line structure, with two radiating patches on top and a director on the side. This creates radiation diversity with directive radiation patterns. The antenna was fabricated and analyzed inside a far-field anechoic chamber. The experimental results validate the return loss, gain, and radiation performance. The measured results of the antenna within a frequency range of 8.5 to 11 GHz show good agreement with the simulation. The antenna has a maximum gain of 9.2 dBi and has the potential to be beneficial for beam steering and X-band applications due to its low profile, broad bandwidth, high gain, and good directivity.

Super-compact equal/unequal half-mode substrate integrated waveguide filtering power dividers using complementary G-shaped resonator

ABSTRACT In this paper, three super-compact equal/unequal filtering power dividers (FPDs) by combining the half-mode substrate integrated waveguide (HMSIW) platform and the metamaterial unit cell are proposed. To miniaturized the total dimension of the proposed equal/unequal FPDs, the evanescent mode technique, the half-mode technique, and the stepped-impedance resonator (SIR) technique have been utilized, simultaneously. In the modified metamaterial unit cell, which is called the complementary G-shaped resonator (CGR) unit cell, the quasi stepped-impedance slot line is replaced instead of the conventional slot line in the circular complementary split-ring resonator (CSRR) unit cell. Accordingly, the electrical size of the modified CGR unit cell is smaller than the conventional circular CSRR unit cell with the same physical sizes. Employing the introduced CGR unit cell and HMSIW structure, three equal/unequal FPDs with arbitrary power-dividing ratios have been designed and simulated. To illustration the performance of the proposed components, three HMSIW FPDs with different power division ratios of 1:1, 1:4, and 1:8 have been fabricated and measured. A reasonable agreement between simulated and measured results has been achieved. The results demonstrate that a miniaturization factor of about 0.64 is achieved.

The structure of the radiation field of a symmetric slot line perpendicular to the edge of an infinite half-plane, taking into account the cross-polarization component

Background. Symmetric slot lines on a perfectly reflecting half-plane are good mathematical models for slot antennas on an ideal plane of finite dimensions, which in practice have a high gain and operate over a wide frequency band. These antennas are used in ultra-fast information processing systems based on microwave and optical volume integrated circuits. Aim. The work presents a solution to the problem of radiation of a perfectly reflecting half-plane, which was excited by a symmetric slot line with a different law of slot expansion. Methods. The problem was solved by the Fourier variable separation method, by which the Green tensor function was obtained, which connects the two components of the antenna radiation field with the excitation field in the gap. Results. It is shown that in the far zone, the radiation field of an ideally reflecting half-plane has two components: the main and crosspolarization. The Green tensor function has a complex form and consists of two terms. The analysis of the Green tensor function shows the participation of each term in the formation of a field in the far zone, demonstrates the mechanism of radiation and leads to known special cases for slot radiators. Conclusion. The validity of the presented mathematical model is confirmed by experimental research.

A Semi-Elliptical UWB Folded Dipole Antenna

In this paper, a novel structure of a semi-elliptical folded dipole for ultra-wideband (UWB) receiving applications is discussed. This proposed antenna has a directive radiation pattern resulting in a high gain over the bandwidth. The design uses a planar technology including a microstrip line to slot line transition and optimized curves to obtain a measured impedance bandwidth of 2.3–26 GHz with the condition of S11 &lt; −6 dB (level accepted for receiving antenna) and meets S11 &lt; −10 dB in several bands. Additionally, the simulated gain ranges from 5 dBi to 9.5 dBi across the entire bandwidth with an efficiency of at least 75%. This antenna model offers a reconfiguration capability. The symmetrical feeding used in this antenna creates the directive behavior. Characteristics of this semi-elliptical folded dipole antenna make it suitable for modern wireless communications, such as 5 G around 3.5 GHz, and easy to integrate in antenna arrays (MIMO systems). The four ports of the antenna also make it a candidate for radiation pattern reconfigurability applications reducing in this way the number of elements in network antennas.

Two‐dimensional multichannel bandpass filter bank with improved fractional bandwidth and selectivity

AbstractThis letter presents a six‐channel bandpass filter bank created on substrate integrated waveguide (SIW) with improved bandwidth and frequency selectivity on the lower band. Through SIW square cavities and slant slots, a two‐dimensional multichannel bandpass filter bank with a transmission zero constructed with the SIW orthogonal resonant modes is produced. The substrate integrated square cavity approach is used to achieve the propagation of the two orthogonal‐oriented transverse electric modes, TE102 and TE201, which resonate on the same frequency and bandwidth, depending on the location of the feed ports. The bandwidth could be altered by the coupling matrix synthesis and coupling windows. Better transmission and bandpass responses are produced in each channel when the feed ports and coupling gaps are positioned and appropriately adjusted. However, a pair of slot lines are imprinted along each cavity's designated diagonal to guarantee better isolation while attaining an increased fractional bandwidth. A 3 × 3 array of six bandpass filters with a center frequency of 8.65 GHz has been built, simulated, and measured to establish the suggested technique. Low insertion loss, high return loss, high isolation, an improved fractional bandwidth, and a compact device were the proposal's advantages.

A Simple Circularly Polarized Beam-Scanning Antenna Using Modulated Slotline-Spoof Surface Plasmon Polariton Slow-Wave Transmission Line

This letter proposes a novel simple planar circularly polarized (CP) frequency beam-scanning (FBS) antenna using slotline (SL) and spoof surface plasmon polariton (SSPP) structure. A new SL-SSPP slow-wave transmission line (TL) is initiated by periodically introducing orthogonal tilted corrugated grooves on both sides of the SL, which can generate orthogonal electric-field components in the same cross-section along the TL, and its dispersion characteristic can be flexibly adjusted. In order to excite an effective radiating mode from the propagating slow-wave mode, a simple double-sided tilted modulation method is devised to periodically modulate the SL-SSPP TL. Further, to obtain the CP characteristic, a π/2 phase displacement between the sinusoidal modulation structures on both sides of the TL is designed. The configuration of presented CP beam-scanning antenna owns the merits of simpler structure, low profile, and single dielectric layer. A prototype is manufactured and then tested to verify the proposed design. The experimental results con-firm that, within the 3-dB axial ratio (AR) bandwidth (from 7.2 to 8.35 GHz), the designed antenna achieves a 35° beam-steering range with CP characteristic. This antenna also realizes appropriate gain and radiation efficiency in the working band.

2-Bit Wideband Electronically Controlled Reconfigurable Phased Array With Wide-Angle Beam-Scanning Capacity

In this paper, a 2-bit wideband electronically-controlled reconfigurable phased array with wide-angle beam-scanning capacity is proposed. Based on the current reversal mechanism and real-time delay design, a wideband 2-bit phase shifter is designed by cascading a wideband 180° phase shifter and a wideband 90° phase shifter. Then, a wideband 2-bit element is established by connecting the radiation area of the Vivaldi structure at the slot line of the phase shifter, and a metasurface slab with H-shaped metal layer is introduced to improve the scanning performance. Further, a planar wideband reconfigurable 2-bit array at 17 GHz has been designed and fabricated based on this element, and a stripline-based 1:16 power divider with the phase-shifting function is designed to simulate the space-fed spherical wave to avoid high sidelobe. Measured and simulated results are in good agreement. The measured results indicate that the main beam of the array can scan from -73° to 73° at 17 GHz by appropriately controlling the state of PIN diodes, and the gain fluctuation is only 2.18 dB. The measured 3-dB gain bandwidth of the array in the broadside direction is about 29.1% (from 14.7 GHz to 19.7 GHz). The wide-angle scanning and wideband performances are verified.

Filtering linear polarization converters based on multi-mode unit for harmonic suppression

In this article, a class of filtering linear polarization converters based on a single quasi-single-layer triangular resonator unit is proposed. By loading the stub-line and slot lines, the degenerate modes of the single fundamental resonant mode of an isosceles right-angle patch are separated into two for a second-order filtering characteristic, and two additional resonant modes are then generated for the second conversion band. Attributed to the mixed electric and magnetic coupling in the coupling section of the loaded stub-line, several conversion zeros are introduced at the same time. As the contribution of this work, multiple resonant modes and conversion zeros can be independently controlled by the corresponding parameters, enabling second-order single- and dual-band response with multi-mode high selectivity side-band and harmonic rejection characteristics out-of-band. With the detailed analysis of the surface current and field distributions, the polarization conversion mechanisms are revealed. Finally, the single-band and dual-band linear polarization converters are processed, and the measured and simulated results are in good agreement. As expected, the two polarization converters show excellent filtering features, which is beneficial for improving modulation accuracy and avoiding unwanted electromagnetic interference in various applications of multi-passband and multi-functional metasurfaces.

Compact high-selective wide-stopband coupled bandpass filter using middle-shorted hairpin-resonators

In this letter, a novel compact highly selective coupled bandpass filter (BPF) with sharp roll-off and wide stopband with excellent attenuation is proposed. This BPF is designed using two middle-shorted hairpin-resonators and a slot line resonator. The coupling matrix is calculated theoretically as per the specifications. The coupling coefficients between the resonators are computed by using the full-wave simulator HFSS to properly select the coupling gap between the resonators. The ABCD and S-parameters of the proposed design are computed, and the S-parameters are plotted theoretically. The designed filter is fabricated and tested. Good agreement is found between simulation and measurement. The proposed filter has excellent measured characteristics, including an insertion loss of 1.2 dB, a return loss better than −20 dB, high band edge attenuation of 60 dB, three Transmission Zeros (TZs), and a wide stopband rejection of greater than 30 dB up to 3f0 where f0 is the center frequency of the BPF. The proposed filter can be used for WLAN applications.