Slot Feed Research Articles

Linear and circular polarization radiation through a modified 270° square ring-fed 2 × 2 array antenna

A novel design of a 2 × 2 array antenna with linear polarization (LP) and circular polarization (CP) characteristics is proposed. Each array elements is composed of a simple ground plane with an inverted L-shaped element and a modified radiating patch based on two inverted L-shaped components. The whole system is fed by a slotted feed line. The proposed single antenna operates over the frequency band of 3–4 GHz, 4.9–5.2 GHz, and 8–14 GHz, whitin which CP is seen at 3.5–4.5 GHz and LP is observed over the remained frequency bands. To improve the performance, four of aforementioned single antennas are arranged in a 2 × 2 array antenna. The feeding mechanism is developed based on a 270° square ring with varying widths in each quarter. Four branches, stemmed from the square ring, are connected to each of the constituent antenna elements for excitation purposes. Proper feeding strategy, suitable design of the elements positions, and wise-tuning of the dimensions of the antenna elements result in coverage of wide bandwidth ranging from 2.8 to 3.8 GHz, 4.5–7 GHz, and 7.3–8 GHz. As noticed, WiMAX and WLAN communication frequency bands are satisfactorily covered. Moreover, CP is attained at the frequency bands of 4.65–4.75 GHz and 5–7.2 GHz.

Compact balanced bandpass filter design using miniaturised substrate integrated waveguide cavities

The contribution of this work is to propose a compact balanced bandpass filter design using the miniaturised full/half-mode substrate integrated waveguide cavities (SIWCs) together with the microstrip coupling slot feed. The circuit area of the proposed full-mode SIWC is only 4.64% of its conventional SIWC counterpart, and the half-mode SIWC further reduces the circuit area by half. Besides the circuit compactness, the non-coupling of the microstrip and the slot in the common-mode (CM) operation provides an excellent CM signal rejection. Prototypes of two-pole full/half-mode balanced SIWC BPFs are fabricated and measured to validate the circuit design. Agreements between measured and simulated data are observed. The CM signal rejection levels are larger than 45 dB over a wide-frequency range with the passband's differential-mode insertion losses around 1.6 and 0.8 dB for the full- and half-mode designs, respectively.

A Circularly Polarized Cavity-Backed Slot Antenna With Enhanced Radiation Gain

A class of circularly polarized (CP) cavity-backed slot antennas with enhanced gain is formed up. All the proposed antennas are implemented in a single rectangular metal cavity. One slot is formed at the bottom side of this cavity as a feeding slot to excite two orthogonal resonant modes. The slot antenna is then constituted at the opposite side of the feeding slot to radiate electromagnetic wave. A two-element array is further implemented to improve the radiation gain with 3 dB enhancement without size increment of the original antenna. Finally, two CP cavity-backed slot antennas are fabricated and tested for experimental verification of the proposed design methodology. A good agreement between measurement and simulation shows the feasibility of the proposed cavity-backed slot antenna.

Design of Dual Band Stacked RDRA for 5G Applications

This paper focuses on the investigation and discussion of three different designs of stacked Rectangular Dielectric Resonator Antenna (RDRA) at dual bands of 25 GHz and 32 GHz for 5G applications. First, basic stacked RDRA. Second, basic stacked RDRA with a single notch. Third, basic stacked RDRA with double notches. All the proposed structure consists of two stacked DRA of dielectric permittivity of 10 which mounted on a Duriod dielectric substrate of dielectric permittivity of 2.2 and feed by Microstrip aperture slot feeding technique (MSA) for 50 Ω characteristic impedance. Authentication of all the proposed designs comparison is completed using 3D simulation tool by observing the performance of reflection coefficient, bandwidth, and gain. All the proposed RDRA are demonstrated simulated reflection coefficient lower than 20 dB for both bands and simulated gain more than 6 dBi. Meanwhile, for simulated bandwidth, only the proposed basic stacked RDRA with single and double notches are demonstrated simulated bandwidth more than 1 GHz, which fulfill the requirement for 5G applications.

Analysis of Broadband Pulse Radiation from a Conductively Loaded Slot Antenna: Performance Evaluation in the Time and Frequency Domains

To investigate the function of a conductive loading profile to a slot antenna, the conductively loaded slot (CLS) antenna was designed, analyzed, and compared to an unloaded slot in various aspects of performance associated with broadband pulse radiation. The time-domain performance in this article includes reflected voltage in the feeding transmission line, slot current and voltage distributions, radiated far-zone electric field, fidelity, and the electromagnetic field in the space of the slot periphery. In the frequency domain, reflection coefficient, broadside gain, and radiation efficiency were demonstrated. The relationship between characteristics of the antennas in the time and frequency domains was compared. The CLS was fabricated on a printed circuit board (PCB) and measured based on diverse scenarios. The features of the CLS in short-pulse radiation and reception applications were verified both numerically and experimentally.

Design of Compact Beam-Steering Antennas Using a Metasurface Formed by Uniform Square Rings

In this paper, we propose two designs of slot-fed metasurface antenna for beam steering applications. Both designs have the same two-layer stacked configuration consisting of either a single-slot or a double-slot radiator and a metasurface superstrate. In contrast to existing phase-gradient metasurfaces with varying unit elements for beam steering, our proposed metasurface is formed by uniform square rings. At operating frequencies, each square ring acts as an individual resonating element. By exciting the elements in sequence with different phase delays through the slot radiator, the generated antenna beam can be steered. In the first design, the position of the single-slot radiator is shifted to achieve the beam steering functionality; while for the second antenna, to avoid mechanically moving the feeding slot, a double-slot-feeding structure is proposed with two slots excited with varying phase differences. Simulation and experimental results show that beam steering angles of −35° to 35° can be achieved for the single-slot-feeding design and beam steering angles of −30° to 30° are realizable for the double-slot-feeding configuration. Comparing with conventional phased array antennas, our proposed designs have compact size with moderate to high antenna gain.

The Comparison on the Side Feed Mode of Micro-strip Patch

Abstract The feeding of the micro-strip patch is flexible and complex, especially side feeding. In this paper, a single micro-strip patch antenna with a center frequency of 2.45GHZ is taken as an example to explore the performance of the slotted feed and non-slotted feed and verified in HFSS15.0. Combined with HFSS15.0 software simulation and theoretical calculation, the corresponding conclusions can be obtained. The theoretical value and simulation results will be shown that: the required 1/4 converter sizes of the non-slotted side feed and slotted side feed are different. By contrasting with sizes of two feeding modes, electrical size of the slotted feed is smaller. It can be known that all performances of the slotted feed are more superior.

A dual-band rectenna using broadband DRA loaded with slot

This paper presents a broadband hybrid slot-dielectric resonator antenna for radiofrequency (RF) energy-harvesting application. The antenna geometry consists of a simple pentagon-shaped dielectric resonator antenna (PDRA) excited by a microstrip feed underlying rectangular slot with narrow notch. It is investigated that the bandwidth of the proposed PDRA is improved significantly owing to electromagnetic coupling between feeding slot and the dielectric resonator. The measured results demonstrate that the proposed PDRA achieves an impedance bandwidth of 110.8%, covering the frequency range from 0.86 to 3 GHz in addition of stable radiation pattern with peak gain of 6.8 dBi and more than 90% radiation efficiency throughout the band, showing its suitability for RF energy harvesting application. For this to be feasible, the developed antenna is matched with the rectifier at two public telecommunication bands of GSM-900 and GSM-1800 using a compact dual-band hybrid matching network. The measured result demonstrates that the proposed dual-band rectenna system provides the peak efficiency of 63 and 59% for a load impedance of 4.7 kΩ at 0.9 and 1.8 GHz, respectively.

Bandwidth enhancement of monopole antenna with DGS for SHF and reconfigurable structure for WiMAX, WLAN and C-band applications

In this study a reconfigurable antenna for WiMAX, WLAN, C-bands and SHF applications has been presented. The main body of antenna includes rectangular and L-shaped slotted ground plane and a rectangular patch with slotted feed line, for impedance bandwidth enhancement. In the proposed antenna, a PIN diode is used to adjust the frequency band to SHF, WiMAX, WLAN and C-bands applications. When PIN diode is forward-biased, the antenna covers the 3.5–31 GHz frequency range (i.e. a 160% bandwidth) and when the PIN diode is in its off-state, it operates between 3.4–5.8 GHz. The designed antenna, with a very small size of 12 × 18 × 1.6 mm3, has been fabricated and tested. The radiation pattern is approximately omnidirectional. Simulations and experimental results are in a good agreement with each other and suggest good performance for the presented antenna.

A Triple-Band Hybrid Rectangular Dielectric Resonator Antenna (RDRA) for 4G LTE Applications

A triple band hybrid rectangular dielectric resonator antenna (RDRA) in place of multiple antennas to cover different bands of 4G long term evaluation (LTE) application is presented. An integrated approach using the combination of radiating slot and higher order mode techniques is employed to increase the number of resonances of a single RDRA. Multiple radiating modes are implemented to achieve three resonance bands 1.8, 2.6 and 3.4 GHz. The triple resonances are created simultaneously due to resonant modes of radiating rectangular ring slot feed coupled together with $$TE_{111}^{x}$$ and $$TE_{131}^{x}$$ modes of RDRA. A parametric study is carried out to investigate the triple resonances characteristics and to obtain optimal design parameters. The obtained optimized design is fabricated and validated experimentally. Impedance bandwidth (|S11| < − 6 dB) of 70% is achieved, fulfilling the broad coverage of LTE-time division duplex bands of (33–43). The measured return loss and radiation pattern are in good agreement with the simulated results.

Wideband low‐profile dielectric resonator antenna with a lattice structure

A new kind of broadband dielectric resonator antenna with a lattice structure is presented. The top dielectric resonator broken up into a lattice structure is adopted to achieve a wide operating bandwidth in a compact size, which makes it suitable to be arrayed. A backed cavity based on substrate integrated waveguide technology is introduced to reduce the unwanted radiation from the surface wave. The antenna is excited through a slot feeding structure. Measured results show that the prototype can achieve an impedance bandwidth of 39% and a peak gain of 9.6 dBi.

Diagnosing the automobile starting system

This article presents a new method for analysing the torque of an internal combustion engine using registered electromechanical runs and magnetic field distribution in a starter. The aim of the study was to develop a model of the starting current of an internal combustion engine and carry out verification tests on real objects. The developed model allows to simulate the shutdown of individual cylinders. Experimental research was conducted using the Bosch FSA 740 equipment for four internal combustion engines under variable operating conditions. During testing, the starting current and relative compression in cylinders were recorded. Simulating the variable load of the starter, the magnetic induction distribution of the magnetic induction was recorded in the feed slot. The research will be used to develop a method of diagnosing the starter and determining the torque of the internal combustion engine.

Asymmetrically CPW-fed ladder-shaped fractal antenna for UWB applications

A compact asymmetrically CPW-fed ladder- shaped UWB fractal antenna is presented. An impedance bandwidth of 4.56---13.1 GHz is achieved by using four iterations of H-shaped radiating element, modified feed line, asymmetrical feeding and slot loaded ground plane. Omnidirectional radiation patterns are achieved in H-plane at all frequency points in the operating frequency band. The bidirectional nature of E-plane patterns at lower frequencies is observed to be shifted to directional nature at higher frequencies. The designed antenna structure has an average gain of 2.84 dB with a constant group delay. The designed antenna structure is analyzed for three different substrate materials i.e. CNT, Ni0.2Co0.2Zn0.6Fe2O4 and FR-4 epoxy. A good agreement is achieved between the simulated and measured results. This antenna structure has advantages of wider bandwidth and smaller dimensions over already reported ones.

Experimentation of Premixed Rotating Detonation Engine Using Variable Slot Feed Plenum

A premixed supply of fuel and oxidizer was fed through five concentric feed slots and detonated in a rotating detonation engine, representing the first known successful airbreathing premixed rotating detonation engine. The premixed feed system successfully arrested flashback. An operating map was constructed and compared to a nonpremixed rotating detonation engine. Mixing effects were shown to be important by comparing measured wave speeds to theoretical Chapman–Jouguet detonation velocities, published computational fluid dynamics results, and similar nonpremixed rotating detonation engines. High-speed imagery indicated that the wave speed measurements should account for the circumferential velocity of the gases relative to the detonation and that the Chapman–Jouguet calculation should account for partial mixing with combustion products.

Design of a Premixed Fuel–Oxidizer System to Arrest Flashback in a Rotating Detonation Engine

Rotating detonation engines offer the promise of pressure gain combustion in aeronautical combustors where (normally) stagnation pressure decreases. For practical reasons, current experimental rotating detonation engine designs include separate streams of fuel and air injected into a detonation channel. Experimentation with a fully premixed rotating detonation engine has repeatedly failed due to flame flashback into the premixed plenum. That fundamental problem is the subject of this paper: understanding the relevant principles and parameters that contribute to flashback and investigating a scheme for arresting the flashback phenomenon. This investigation quantifies the flashback susceptibility for a proposed rotating detonation engine feed slot with parameterization of channel height, channel length, equivalence ratio, fuel type, and feed pressure. The design principles of quenching distance and critical boundary-layer velocity gradients are shown to describe the safe operation region to deliver a safe premixture of fuel and air to a rotating detonation engine when adjusted for experimental conditions and applied in unison. This research leads to a design that is capable of avoiding flashback while enabling detonation to occur in a rotating detonation engine.

Wideband Cylindrical Dielectric Resonator Antenna Operating in HEM11δ Mode with Improved Gain: A Study of Superstrate and Reflector Plane

A wideband and high gain dielectric resonator antenna (DRA) operating in hybrid HEM11δ mode is proposed. The investigated geometry employs one cylindrical dielectric resonator partially covered with a transparent dielectric superstrate and backed up by a single side metal coated dielectric reflector plane. The reflector is dedicated for gain enhancement while the superstrate is employed for merging of two resonant bands resulting in a single wide band. The dielectric resonator is excited by simple microstrip feed slot coupling technique and operates over X-band, ranging from 7.12 GHz to 8.29 GHz, that is, of 15.18% impedance matching bandwidth with 11.34 dBi peak gain. The different development stages like standalone DRA, DRA with superstrate, DRA with reflector, and DRA with both superstrate and reflector plane with respect to bandwidth and gain performances are analyzed properly. To the best of authors’ knowledge, this is the first time this type of combination of both superstrate and reflector plane is demonstrated in DRA engineering. An antenna prototype was fabricated and characterized and a very good agreement is achieved between the simulated and measured results.

Placement‐insensitive flexible RFID antenna for ‘peel‐and‐stick’ applications

Radio-frequency identification (RFID) systems with ‘peel-and-stick’ labels are currently limited to tracking items with nearly electromagnetically transparent material properties. This limitation stems from the antenna choice for these labels – a dipole variant. A ground plane edge treatment along with a feed slot with unique tuning capabilities is investigated as an alternative RFID antenna option. Ease of fabrication was maintained as a priority in all design decisions. The measured antenna displays true placement insensitivity with a constant impedance when attached to metal, lossy dielectric, or electromagnetically-transparent objects.

Five‐element ESPAR antenna using the annular ring slot active element

ABSTRACTThis study proposes a five‐element electric steerable parasitic array radiator (ESPAR) antenna that uses annular ring slot feeding and can be applied to Beamspace MIMO communication. A typical dipole active element that can be applied to the ESPAR antenna usually has a cylindrical structure. Since the coaxial cable is located inside the cylinder, it is restricted by the diameter of the dipole. In the proposed annular ring slot active element, the annular ring slot is formed on the outer conductor, and then the inner conductor is put into the outer conductor to be fed. The typical dipole active element currently takes a cylindrical shape, and therefore has a omnidirectional pattern. Therefore, it generates identical radiation patterns, regardless of the number of parasitic elements. Moreover, in the proposed method, it is easy to undertake impedance matching that controls the length, diameter, and thickness of the slot, outer conductor, and inner conductor. Furthermore, since the dielectric cylinder is located between the outer and inner conductors, it is structurally solid. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2800–2804, 2016

Design of clover slot antenna for biomedical applications

A new clover slot antenna operating at 2.45GHz Industrial, Scientific, and Medical (ISM) band for biomedical applications is presented and experimentally verified. By putting a single feed and truncating clover slots with extra perturbation, good performance of polarization can be achieved. Also, the miniaturized size of the proposed antenna is 14×12×0.8mm3 by utilizing the clover shaped slots. A broader bandwidth of 2.5GHz is obtained for reflection coefficient less than −10dB. In addition, the radiation pattern of proposed antenna exhibits the maximum gain of −6dBi.

Compact meandered‐shape electromagnetic bandgap structure using in a microstrip array antenna application

ABSTRACTIn this letter, a novel spiral shape for electromagnetic bandgap structure (EBG) is presented for array structure. By implementation of the spiral formation, the inductance of the EBG unit cell will be increased and the unit cells are compacted around 36% for 3.6 GHz in comparison to conventional EBG unit cells. The prototype model of unit cells is used for 2 × 2 element microstrip patch array antenna with slot feed for improving the radiation gain of the antenna by reducing the mutual coupling effect of the antenna. Suppression of surface waves using EBG has improved the gain about 1.2 dB. Finally, an antenna prototype was fabricated and tested. Good agreement between simulation and measurement is obtained that verified the performance of the proposed structure. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2084–2088, 2016