Planar Slot Antenna Research Articles

A hybrid solar and RF energy harvester for applications of self-Powered wireless sensor nodes

A hybrid solar and RF energy harvester is proposed for applications in self-powered wireless sensor nodes. A planar slot antenna array backed by substrate integrated waveguide (SIW) cavity is produced for RF energy harvesting. A designed rectifier connected to the antenna array converts the received RF energy into DC energy. Solar cells are placed on the rest of the antenna array except slots, fully utilizing the array's surface. The solar cell coverage ratio reaches 87%. The measurement results indicate that under solar simulator illumination, the solar energy harvester has a short-circuit current of 15.7 A, an open-circuit voltage of 0.542 V, and a maximum output power of 5.81 W. Under the RF power density of 85.5 μW/cm2, the RF energy harvester reaches its peak power conversion efficiency (PCE) of 69%. All simulated and measured results are in good agreement, verifying the capabilities of the designed hybrid harvester.

Novel High Efficiency V‐Band Pure TEM D‐PRGW Antenna for 5G mmWave Applications

ABSTRACTThis paper starts with the proposal of an enhanced version of a planar rectangular slot antenna fed by the quasi‐TEM printed ridge gap waveguide (PRGW), attended with a numerical study of a miniaturization procedure showing the limitations of the conventional PRGW‐based antennas. Then innovative solution is introducing a new miniaturized pure TEM wide‐band slot antenna utilizing double PRGW (D‐PRGW) technology; the proposed approach is self‐packaged and shows high potential for enhancing antenna performance, particularly in terms of bandwidth, gain, and compactness. This technology is featured with low loss, high performance, and compact size; it consists of surrounding the ridge area with a double layer of electromagnetic band gap (EBG) lattice instead of one to eliminate the surface waves effectively and keep the signal completely confined inside the ridge area with strict minimum rows of EBG. Therefore, a broad impedance matching bandwidth (|S11| ≤ −10 dB) of 33.33% is obtained from 50 to 70 GHz, which covers the unlicensed NR parts (n262; amp; n263) of the V band. Furthermore, the antenna achieves a peak gain of approximately 16 at 65 GHz while the overall efficiency remains above 90% across the entire operating frequency band. The high performance along with the compact size of this novel design makes it a good candidate for 5G wireless communications applications centered around 60 GHz.

A Circular Shape Arc Slot Ultra-Wideband Antenna for Biomedical Applications

In modern communication systems, ultra-wideband (UWB) technology has garnered substantial attention due to its superior attributes compared to traditional narrowband communication systems. Over the past decade, UWB technology has also found applications in microwave-based imaging systems. This study introduces a simple planar coplanar waveguide-fed circular shape arc slot antenna designed specifically for biomedicine and microwave medical imaging applications. The proposed design is implemented on a 1.6-mm-thick FR4 substrate with a relative permittivity of 4.4 and a loss tangent of 0.0009. The antenna has physical dimensions of 26 mm × 29 mm and achieves an impressive bandwidth of 16.6 GHz, spanning 2.4 to 19 GHz. It exhibits a peak gain of 2.5 dBi and consistent omnidirectional radiation characteristics. Thorough temporal analysis validates the antenna's performance within acceptable limits, which is further affirmed through practical fabrication and testing, demonstrating strong agreement with simulation results.

Wideband meander-line-antipodal-vivaldi slot-antenna for millimeter-wave applications

An antipodal Vivaldi monopole radiator is employed in an innovative wideband planar slotted meander antenna. A quarter-wave microstrip feed is coupled to the antenna for a ground reflector plane over a meander line with five right and left antipodal Vivaldi (RLAV) slots on either side and a series of Z, inverted U and inverted Z-shaped turns. The FR4 substrate with a relative permittivity of 4.4 and modest dimensions of 50 × 20 × 1.6 mm3 is used to implement the proposed antenna. A 17.39% fractional bandwidth of -29.10dB (S11 <-10dB), an average radiation efficiency of 73%, and a gain of 6.7dBi at the central frequency of 28GHz. The outcomes of using RLAV arms at the centre of the meander structure enhance the antenna’s performance validated using the high-frequency structural software Ansys 2022R1, which is a finite element method (FEM) tool. The measured results indicate that the bandwidth enhancement has been fine-tuned for use in the 5G millimetre wave band in the Frequency Range 2 (FR2) n261 frequencies, the 3rd generation partnership project (3GPP) band n257, and the Federal Communications Commission’s (5G) high-band spectrum (25-30GHz).

Gain-enhanced and Mechanical Reconfigurable Slot Antenna with Metasurface

A novel wideband slot antenna with metasurface is presented. In order to achieve broadband, high-gain, and mechanical reconfigurable performance, a metasurface is adopted and combined with a new-type planar slot antenna The antenna and metasurface are designed on F4B substrate, and the overall dimension of the antenna is 1.48λ0×1.48λ0×0.2λ0 (λ0 is the free space wavelength at center frequency). Different from the traditional square metasurface, a structure with different properties in the x and y directions is utilized in the proposed antenna, which can be reconstructed by adjusting the relative position between the slot antenna and the metasurface. By introducing the metasurface, the maximum gain of the whole antenna is improved. The antenna works in two states with respect to the two locations of the metasurface. The impedance bandwidth of the proposed antenna in state A is from 5.49 to 9.40 GHz (52.5%), and the impedance bandwidth of the proposed antenna in state B is from 5.83 to 6.01 GHz (3%) and 7.05 to 9.62 GHz (30.8%). The gain of the whole antenna in both states is higher than that of the original slot antenna (without metasurface), and the maximum gain is 9.1 dBi.

Design and Analysis of a Slotted Planar Antenna with Parasitic Ring Patch for Efficient 5G Microwave Applications

Design and Analysis of a Slotted Planar Antenna with Parasitic Ring Patch for Efficient 5G Microwave Applications

Evaluation of Transmission Characteristics of 120-GHz-Band Close-Proximity Wireless Links Using Split-Ring-Resonator Absorber Integrated Planar Slot Antenna

Evaluation of Transmission Characteristics of 120-GHz-Band Close-Proximity Wireless Links Using Split-Ring-Resonator Absorber Integrated Planar Slot Antenna

Directivity‐enhanced planar slot antenna backed by substrate integrated waveguide cavity

AbstractIn this paper, a directivity‐enhanced planar slot antenna (PSA) backed by substrate integrated waveguide (SIW) cavity is proposed to solve the problem of maximum gain direction bias. According to the radiation principle of slot antenna, the reason for maximum gain direction bias is explained and the solution has been given. Ulteriorly, the problem of frequency bias caused by changing the directivity is also explained by resonance modes and solved by introducing the metal via. An example with 5.8 GHz which has the maximum gain of 5.28 dBi and the total thickness less than λ/4 is given. After structural optimization and measurement, the maximum radiation direction of improved antenna is 0° from the normal direction of antenna surface, and it maintains the good radiation performance and small size of the traditional PSA backed by SIW cavity.

A Planar SIW-Based Mm-Wave Frequency-Scanning Slot Antenna Array With No Scan Blindness at Normal

Planar antenna reflectors are the modern design trend of both multibeam and frequency-scanning antenna arrays. The planar implementation of reflectors is typically performed using substrate-integrated waveguide (SIW) technology. A reflector’s profile can be different from the canonical one (parabolic, elliptic, hyperbolic, etc.) because of the effect of spatial dispersion of the reflection coefficient of the SIW-based surface. It should be synthesized considering the magnitude and argument of the field reflected from such a surface to maximize the efficiency of the reflection. In this article, we present a planar millimeter-wave (mm-wave) slot antenna array with SIW-based horn–reflector feeding. We analytically formulate the optimization of the SIW surface dimensions while accounting for the spatial dispersion of the reflection coefficient. We minimize the dimensions of the planar horn–reflector feeding. Finally, we demonstrate that using a dual-slot radiating element, and we can avoid the effects of scan blindness along the normal direction. A prototype has been built and a good agreement has been achieved between the measured results and the predicted results based on calculations. The prototype achieved ±17° beam scanning within 16% of the operational frequency range, with no scan blindness along the normal direction.

A Synthesized Dual-Polarized Planar Slotted Antenna Array for SAR Sensors

A Synthesized Dual-Polarized Planar Slotted Antenna Array for SAR Sensors

Phased Array With Pattern Shaping and Scan Loss Reduction for Millimeter Waves

In this work, we investigate antenna architectures to implement dual-mode operation in phased array designs. Planar slot antenna elements are used in array configuration, in combination with artificial dielectrics layers (ADLs) located in the close proximity of the array, to achieve pattern shaping. The artificial dielectric superstrate supports the propagation of leaky waves that can be optimized to enhance the gain in a specific angular region or to enlarge the array field of view. By controlling the amplitude and phase of the antenna elements, the radiation patterns can be combined to realize either wide or narrow beams. This concept present advantages for both millimeter-wave (mm-wave) communication and radar applications. A design of a four-element array fabricated in standard printed circuit board (PCB) technology validates the feasibility of the dual-mode operation. The measured results also show good agreement with simulations.

High‐gain ultra‐wideband quasi‐conical beam Fabry‐Perot antenna based on beam switching

To solve the contradiction between the high gain and wide coverage, the concept of the quasi-conical beam is proposed by using the high-gain pencil beam electrically switching along a cone to make full use of time redundancy. In a periphery-fed Fabry-Perot (FP)-type multi-beam antenna, the electrically switching is used to activate the different port corresponding to the different beam for the beam switching in the azimuthal plane, and the varying frequency is used for the continuous scanning in the elevation plane. Different from the lens or matrix multi-beam arrays, in this scheme, the FP cavity serves as both the beamforming network and the radiator to produce the multi-beam. Around eight planar antipodal Fermi-tapered slot antennas are placed around the FP cavity between the partially reflective surface and the metal ground plane as the primary feeds. The simulation and measurement results show that a relative impedance bandwidth of 53.3% with reflection coefficients below −10 dB from 11 to 19 GHz is obtained and the peak gain is 17.1 dBi at the central frequency of 15 GHz. The results also show that a high-gain beam scanning from 22° to 59° in the elevation plane is achieved and the peak gains are between 16 dBi and 20 dBi. In addition, when the electrically switching of the beam is along a cone, the proposed antenna may form quasi-conical beam. And in some applications, it may replace the conventional conical beam antenna with the advantages of wide coverage and high gain.

Arrayed Photomixers for THz Beam-Combining and Beam-Steering

In this study, generating and enhancing THz continuous/pulsed waves is achieved by fabricating a monolithic InP substrate chip of arrayed photomixers, where each photomixer includes an InP/InGaAs uni-traveling-carrier photodiode (UTC-PD) with integrated 1 × 4 planar slot antennas (PSAs). Through optoelectronic time-aligned and -gradient delays of lightwaves that couple to arrayed photomixers, the radiated THz waves yield both quantitative gain and spatial directional gain. To generate continuous 300 GHz waves, each UTC-PD is excited at a photocurrent of 3 mA to attain −15.79 dBm THz power that exhibits 12 dB combined gain by four arrayed UTC-PDs. Whereas, −17.71 dBm THz pulse generation with a duration of 25 ps can be achieved at the same optical pump power. The results show that the power enhanced gain of THz pulses is around 10 dB, which is less than that of continuous THz waves, because a part of the generated frequency components of the THz pulse is significantly deteriorated by bandwidth-limited PSAs. Furthermore, by means of optoelectronic time-gradient delay with frequency-independent characteristics, we successfully demonstrate steering of continuous and pulsed THz waves repeatedly in a range of 30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> and 20 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> , respectively. In conclusion, strengthening directional THz power by beam-combining and -steering with arrayed photomixers is a promising technique for effective generation of continuous/pulsed THz waves.

Planar High-Gain Millimeter-Wave Slotted SIW Cavity Antenna Array with Low Sidelobe and Grating Lobe Levels

In this paper, a planar high-gain millimeter-wave (mmW) slotted substrate integrated waveguide (SIW) cavity antenna array with low sidelobe and grating lobe levels is proposed. The antenna consists of a slotted SIW resonator and an SIW transmission line (TL). To achieve a high gain and simplify the structure of the antenna element, the slotted SIW cavity is resonated in high-order mode. Then, a high-gain antenna array is implemented with only four such elements. By analyzing the pattern multiplication principle of the antenna array and accurately adjusting the element spacing, the high grating lobe level caused by the large spacing of the high-order mode resonator is considerably reduced. In addition, a one-four unequal amplitude power divider is introduced to further reduce the antenna array’s sidelobe levels (SLLs). Finally, the proposed antenna array is fabricated for verification. The measured peak gain is 21.4 dBi at 27.3 GHz. The measured grating lobe level in the E-plane is reduced to −17.9 dB, and the measured SLLs are lower than −19.1 dB.

Miniaturised ultra-wideband rectangular shaped slot antenna for ground penetrating radar applications

Abstract In the proposed work, a miniaturised ultra-wideband tapered slot planar antenna with the aim of gain enhancement, working bandwidth containing lower frequency range, and improving antenna efficiency is presented. The proposed antenna consists of a slotted patch printed on the top layer of FR4 substrate with three 50-Ω resistors connected in the slotted arms and bottom layer consists of an optimized ground plane with a non-uniform parasitic patch which is used to achieve circular polarization in the frequency range of 2.4–2.6 GHz. The measured impedance bandwidth of the proposed antenna is 0.3–4 GHz with a peak gain of 3.2 dBi. The overall antenna efficiency is 83% and radiation patterns of the proposed design on different frequencies are shown to confirm the proposed antenna result, especially at lower frequencies. The proposed antenna can be used for the detection of artifacts in the deeper ground known as ground-penetrating radar applications.

A Miniaturized Wideband Planar Bow-Tie Slot Antenna with Asymmetric CPW

In this paper, a novel miniaturized wideband planar bow-tie slot antenna is proposed. For the purpose of miniaturization and wide bandwidth, the effects of the dimension and shape of the bow-tie slot and feed structure are analyzed. This antenna adopts a water droplet slot, fed by an optimized asymmetric coplanar waveguide (CPW). By adjusting the feeding line, the impedance characteristic of the antenna is greatly improved that leads to a broader bandwidth. The proposed antenna operates from 2.8 GHz to 5.25 GHz with a gain of 3.8 dB. Compared with the traditional triangle bow-tie antenna, the relative bandwidth of the proposed antenna is broadened to more than 61%, while the size is reduced by about 36%, which indicates the proposed antenna is suitable for a variety of wireless applications.

A novel dual-port dual-layer planar spiral slot multiband antenna

In order to realize a dual-port multiband antenna, a novel planar spiral slot antenna is proposed and analyzed. The antenna adopts a dual-layer substrate structure. A spiral slot is etched on its bottom metal surface with a ring gap beside the slot to improve the isolation and lower the frequency. An elliptical metal ring radiation unit in the middle surface of the antenna plays the role of radiating and impedance matching. Two mutually perpendicular microstrips on the upper surface are used for feeding the radiation unit. The simulation and test results show that two ports of the antenna can work at multiple frequencies with the same radiator, and the isolation is more than 13.5 dB in the working bands (1.86-1.99 GHz, 2.47-2.5 GHz, 2.57-2.64 GHz, 2.90-5.7 GHz and 6.35-9.66 GHz). The antenna has the advantages of high gain, small volume, quasi omnidirectional radiation, and so on.

A Frequency-Reconfigurable Planar Slot Antenna Using S-PIN Diode

A novel frequency-reconfigurable solid-state plasma chip antenna based on plane slot is proposed. The radiation slot of the antenna is embedded with a surface-PIN (S-PIN) diode and fed by a microstrip line through electromagnetic coupling. The state of the S-PIN diode can be switched by applying a forward bias voltage to realize the reconfigurable radiation slot of the antenna. The structure parameters of the S-PIN diode have been optimized. The overall size of the silicon-on-insulator (SOI) substrate is controlled at 20 × 10 × 0.35 mm. A prototype of the proposed antenna is fabricated and measured. The measured results show that the proposed antenna can realize cross-band frequency switching from 6.8 to 15.5 GHz. Meanwhile, the normalized radiation patterns show prominent reconstruction characteristics as the bias voltage changes. The proposed solid-state plasma antenna offers high integration compared with traditional reconfigurable antennas. The experiment results validate the applicability of the S-PIN diodes to manufacture reconfigurable planar slot antennas.

A Quadrilateral Shaped Fractal Slot Planar Antenna for Ultra-Wide Band Applications

ABSTRACT This paper presents a low-profile quadrilateral-shaped fractal slot planar antenna using a novel fractal geometry where circular, triangular and regular hexagonal motifs are iterated to form antenna elements. It consists of a partial ground plane and a triangular fractal-shaped patch fed by a microstrip line having an I-shape rectangular slot to increase the bandwidth. A compact 32 × 22 mm2 fractal antenna proposed here is investigated to evaluate its performance in ultra-wideband (UWB) applications. The bandwidth of 15.5 GHz ranging from 3.57 GHz to 19.07 GHz with voltage standing wave ratio (VSWR) less than 2 in the entire operating band is achieved. Simulated values of realisable gain (6.8 dBi), impedance bandwidth (15.5 GHz), radiation efficiency (90%), radiation patterns and group delay evaluation indicate that the discussed antenna is favourable for UWB applications such as world interoperability microwave access, wireless local area network, 5 G, X-band, C-band, S-band and Ku-band. The proposed antenna is fabricated, and measured results are compared with simulated results as well as with those reported in the literature.

Circularly Polarized Hexa-Band Planar Slot Antenna for WLAN and Wireless Communication Application

Circularly Polarized Hexa-Band Planar Slot Antenna for WLAN and Wireless Communication Application