In this paper, a low-profile fractal antenna with square ring slots is reported. The newly proposed fractal antenna includes circular ring radiating elements with orthogonally placed square shape slots to achieve ultra wideband operation. The compact antenna (32 × 28 × 1.6 mm3) is designed and fabricated on an FR4 dielectric substrate, and measurements are performed in the laboratory environment. The simulated and measured results demonstrate that the antenna has -10 dB impedance bandwidth of 9.4 GHz from 4.2 to 13.6 GHz in the ultra-wideband frequency. The measurement results reveal that the antenna has broadband radiation characteristics with peak gain of 5 dB in the desired band of operation. The proposed antenna has low cross polarization of -28 dB and radiation efficiency about 88% in the operating bandwidth. The large bandwidth, low cross polarization, and stable radiation characteristics of the proposed antenna confirm that the antenna may be suitable for ultra-wideband applications.
A Clown-shaped patch antenna for super wideband applications is presented. The radiator is placed on a 1.6 mm thick, RT/Duroid 5880 substrate and is fed using a 50 Ω symmetric coplanar waveguide. The size of the proposed antenna is 26 × 27 mm2 (0.256λL × 0.266λL, where λL is the wavelength at the lower band edge frequency i.e. 2.96 GHz). The radiator is a combination of an ellipse, a rectangle, and a triangle. An impedance bandwidth of 2.96 GHz to more than 100 GHz (i.e. more than 33.78:1 ratio bandwidth) is achieved. Nearly-omnidirectional radiation patterns with an average gain of 6 dBi are achieved. A fractional bandwidth greater than 188.5%, a size reduction of ~97%, and a comparable bandwidth dimension ratio of 2768 are achieved. The investigated antenna has additional advantages like compactness, planar geometry, and super-wide bandwidth.
The aim of this study is to provide a topological optimization method for ship detection in synthetic aperture radar (SAR) imagery. The method consists of three steps: pre-processing, sparse representation and classification. For the first step, the variational model is used for SAR image filtering. For the second step, the curvature of the surface manifold is constructed for sparse representation of target. For the third step, the topological derivative method is adopted to locate the target. Experiments show that the proposed method is effective in reducing false alarms, and obtains a satisfactory detection performance.
This letter proposes a miniature bow-tie antenna element and its 2 × 2 arrays based on ball grid array (BGA) packaging technology for 5G millimeter-wave new radio (NR) applications. The antenna substrate uses ultra-economical single-layer FR4 printed circuit boards (PCB) to reduce manufacturing costs. By adopting solder balls, the antenna achieves the BGA packaging and realizes the surface mounting function. One bow-tie patch is excited by a plated through-hole (PTH) connected to the feeding point. The other bow-tie patch is directly short connected to the ground plane by another PTH. Besides, the bottom ground plane can be equivalent to a reflector, allowing the antenna element and array to obtain broadside radiation. For ease of integration, the input impedance of the antenna is set to 50 Ω. The measurement results show that the -10 dB bandwidth of the antenna element is 21% covering 25.2 to 31.1 GHz. The measured peak gains of the antenna element and the 2 × 2 arrays are 7.6 and 10.75 dBi, respectively. The proposed antenna element and array cover N257 (26.5-29.5 GHz) and N261 (27.5-28.35 GHz) bands. It is very suitable for the 5G millimeter-wave application.
A 37-43 GHz endfire antenna based on ball grid array (BGA) packaging is proposed for the fifth-generation (5G) wireless system. The antenna consists of a miniaturized radiator and reflector. Besides, the radiator is fed by a substrate integrated waveguide (SIW). Furthermore, the RF transition from the SIW to grounded coplanar waveguide (GCPW) and vertical quasi-coaxial is realized on the substrate. The antenna is implemented on a single-layer substrate using standard printed circuit board (PCB) technology to reduce costs. Then, the cost-effective antenna element is reflow soldered with solder balls to form a BGA packaging. The advantages of the BGA packaging and the three-dimensional (3D) integration are discussed in detail. The miniature packaging achieves a compact size of 7 mm × 3.4 mm × 0.6 mm. Finally, a prototype was manufactured to verify the performance. The measurement results show that the proposed antenna is a good candidate for 5G millimeter-wave (mmWave) New Radio (NR) applications.
The letter presents a compact, cost-effective, and surface-mount patch antenna element for 5G millimeter-wave (mmWave) system integration. The antenna element adopts ball grid array (BGA) packaging technology to achieve surface mount function, which can be applied to highly integrated systems. By adding a ring slot on the radiating patch, the proposed antenna obtains a wider impedance bandwidth. The antenna prototype has been simulated, manufactured, and verified. The proposed antenna element size is 5 mm × 5 mm × 1.3 mm. The measurement results show that the proposed antenna element can be used in the N257 (26.5 to 29.5 GHz) and N261 (27.5-28.35 GHz) frequency bands.
We demonstrate that the future sixth generation (6G) radio links can be utilized for sub-THz frequency imaging using narrow beamwidth, high gain, lens antennas. Two different lenses, a bullet or hemispherical shape, were used in radio link setup (220-380 GHz) for an imaging application. Lenses performed with the gain of 28 dBi, 25 dBi, and narrowed the beamwidths of 1° and 2.5°. Plants were used as imaging objects, and their impacts on radio beams were studied. For assessment, the radio link path loss parameter was -48.5 dB, -53.2 dB, and -57.1 dB with the frequency 220 GHz, 300 GHz, and 330 GHz, respectively. Also, the impact of the radio link distance on the imaging was studied by 50 cm and 2 m link distances. In addition, the 3D image was acquired using the phase component of the image, and it showed the leaf surface roughness and the thickness, which was similar to the measured value.
A novel wide beamwidth microstrip patch antenna fed by a 1:5 unequal Wilkinson power divider with a low profile of 0.027λ0 is presented. A circular patch and an independent feeding concentric metal ring can realize the broad half-power beamwidth (HPBW) in the far field. A 1:5 unequal Wilkinson power divider is designed as the antenna feed. The HPBWs of the antenna reach 258° and 267° in XZ-plane and YZ-plane, respectively, covering the whole upper half space at central frequency (2.54 GHz). The results of simulation and measurement show great consistency.
A multi-stack anisotropic cylindrical dielectric resonator antenna with high gain and wide bandwidth is reported. This antenna is designed with three different stacks, and each stack consists of a multilayer dielectric structure to emulate uniaxial anisotropy. Multi-stack, multilayer structure is responsible for producing wide bandwidth and high gain. In addition, the antenna is surrounded by cylindrical metallic cavity to increase directivity in broadside direction. Similar simulated and measured results indicate a wide impedance bandwidth of 37% along with a maximum gain 9.25 dB.
In this paper, a compact and reconfigurable rectangular substrate integrated waveguide structure dual-mode configuration based dual-band band-pass filter has been presented for 5G communication and milli-meter-waves. The dual-band bandpass filter is realized by utilizing the two pairs of dumbbell-shaped defected ground structure. The dumbbell-shaped defected ground structures etched on both the ground and the top side of the cavity have been used to produce transmission zeros, minimize the circuit size, and enhance the passband characteristics at a particular frequency of operations. In an effort to demonstrate the proposed dual-band substrate integrated waveguide band-pass filter, the proposed configuration has been designed and fabricated at the 28.3 GHz and 38.5 GHz frequency using low-cost PCB technique. The centre frequency of the second pass-band has been easily tuned using the geometrical parameters of the filter to achieve the desired applications in the 5G frequency band. Furthermore, the measured in-band return loss (rejection attenuation) of the two bands is approximately better than 26 dB and 28 dB respectively. The insertion loss of not more than 01 dB for both bands of the filter has been achieved. This dual-band filter operating at the licensed frequencies for the 5G spectrum bands renders this filter appropriate for numerous 5G and millimeter-wave communication applications.
A dual band flexible antenna for applications at 900 and 2450 MHz is proposed in this paper. The antenna offers a compact size of 0.23λo × 0.120λo × 0.0007λo, where λo is the wavelength at the lower resonance. The antenna comprises a simple geometrical structure consisting of a W-shaped serpentine structure fed by a microstrip line, while a Defected Ground Structure (DGS) technique was utilized with a partial ground plane to achieve wide operational bandwidth. An additional capacitor was loaded in between the slots to achieve a higher resonance, thus resulting in a compact dual band antenna. Various performance parameters were analyzed, and results were compared with the measured ones. The antenna offers good performance in terms of size, bandwidth, gain, and radiation pattern and thus increases the potential of the proposed antenna for both rigid and flexible devices.
In this letter, a compact dual-band patch antenna based on ball grid array (BGA) packaging for 5G mmWave is proposed. The patch antenna adopts a U-slot and a shorting pin to achieve dual-band operation of 28 GHz and 37 GHz. A single-layer FR4 substrate provides cost-effective features for the massive application. The BGA packaging not only reduces the size but also enables the antenna to be surface-mounted with other components in the same package, which improves the integration. The antenna has been fabricated and measured, and an acceptable agreement was obtained between the simulation and measurement results.
A novel coplanar waveguide (CPW) fed wide slot antenna for broadband circular polarization (CP) operation is proposed in this letter. Utilizing an asymmetrical ground plane and an open slot, broadband axial ratio and good impedance characteristics can be obtained in the middle and low bands. The perturbation patch on the right side of the wide slot excites the upper-band CP mode. By adjusting the upper-part feedline and the wide slot structure, the axial ratio performance can be optimized to a wideband axial ratio bandwidth (ARBW). Compared with wide slot antennas of similar size, the proposed antenna has a simpler structure while achieving a wider ARBW. The proposed antenna has been fabricated and tested. The measured results show that the -10 dB impedance bandwidth (ZBW) is 2.40-7.55 GHz (103.5%); 3-dB ARBW is 2.47-6.2 GHz (86.0%); and the peak gain is about 4 dBic. Right-hand circular polarization (RHCP) radiation pattern is achieved in +z direction. The proposed antenna can be used in WLAN/WiMAX applications and various wireless communication systems which require broadband ZBW and ARBW.
This paper proposes two low divergence angle orbital angular momentum (OAM) Fabry-Perot (F-P) antennas with nonuniform superstrates. There are two steps to design the proposed two F-P antennas. First, two primary array antennas (a slot array antenna and a patch array antenna) are designed. Both antennas can generate OAM vortex beams with a mode of -1. Second, two F-P resonator cavity antennas are formed by loading a nonuniform partially reflective surfaces (PRS) superstrates above the two primary antennas in order to increase the antenna gain and reduce the divergence angle. The PRS is designed non-uniform for increasing the aperture efficiency. The measured results indicate that the F-P OAM antennas can obviously improve the performance of primary OAM antennas: (1) for the slot array antenna, the divergence angle reduces from 27° to 18°, and the maximum gain increases from 5.2 dBi to 7.5 dBi; (2) for the patch array antenna, the divergence angle decreases from 30° to 18°, and the peak gain increases from 3.4 dBi to 7.2 dBi.
Artificial material has the feature to realize a controllable effective permittivity, which leads to many potential applications in the RF and optical fields. In this study, an artificial material is proposed for a Resonant Cavity antenna (RCA) to enhance the gain of patch antenna. The artificial material is made of a lot of circular conducting patches in a uniform size hosted in an FR-4 substrate. The fabricated artificial material is in a square shape with a length and width of 52 mm × 52 mm and a thickness of 1.2 mm. The artificial material is set in front of a patch antenna to construct an RCA, and the gain property of the proposed RCA is evaluated with the simulation and measurement methods. The results by both the simulation and measurement methods prove that the gain is enhanced by the proposed artificial material. The maximum gains are 14.5 dBi in simulation and 12.8 dBi in measurement at 15 GHz for the RCA with on slab of the artificial material. The gain is improved compared to the gain of a patch antenna without the artificial material.
A low-profile half-mode substrate integrated waveguide (HMSIW) filtering antenna with high frequency selectivity is proposed in this letter. The proposed antenna with a height of 0.014λ0 (λ0 is the free-space wavelength) consists of a slot-loaded HMSIW cavity, two parasitic patches, and five shorting pins. An upper-edge radiation null is generated by the interaction between the HMSIW cavity and parasitic patches. A rectangular slot etched on the HMSIW cavity is adopted to generate another null to improve the filtering performances at the upper stopband. Besides, the radiation in the lower stopband is suppressed by two nulls which emerge due to placing shorting pins under two parasitic patches. Thus, four radiation nulls can be obtained to enhance the frequency selectivity. The measured results illustrate that the proposed antenna provides an impedance bandwidth of 4.3% ranging from 2.74 to 2.86 GHz and a peak gain of 6.76 dBi during the operating frequency band. Moreover, four radiation nulls appear at 2.34, 2.56, 3, and 3.24 GHz in the lower and upper stopbands.
In this work, a diversity antenna with a high level of isolation is presented in this paper. To make the antenna compact, the radiating parts are arranged on opposing sides of the substrate. The isolation between the ports is sufficient for the use of a MIMO system, which is achieved through the orthogonal positioning of radiating elements. Wideband and narrowband antennas are placed on opposite sides of the substrate. The suggested monopole antenna has an impedance bandwidth of 3.1 GHz to 14.9 GHz, whereas the rectangular narrowband antenna has an impedance bandwidth of 5.4 GHz to 5.62 GHz. More than 16 dB of isolation exists between the two ports. The proposed antenna has a maximum gain of 2.9 dB. The diversity nature of the proposed MIMO antenna is studied in terms of Envelope Correlation Coefficient (ECC), Diversity Gain (DG), and Total Active Reflection Coefficient (TARC).
In this paper, a design method of spaceborne multi-beam antenna array is proposed. Multi-beam is achieved by rotating subarrays. A high efficiency circularly polarized horn antenna array working in Ka band is designed and processed. The antenna array has 16 large axial ratio elliptical beams, which can achieve the beam coverage range of 53°×49.1°. The simulation results are basically consistent with the test results, verifying the effectiveness of the proposed method. The design method of multi-beam antenna proposed in this paper can meet the requirements of multi-beam seamless coverage.
This letter presents a low-cost dual-band circularly polarized microstrip antenna for GNSS applications. The dual-band operation is achieved by stacking two metallic patches on a conventional FR4 substrate. The designed antenna can cover GPS L1 band, BeiDou B1 band, Galileo E1, E5b bands, and GLONASS G1, G3 bands, through a bandwidth of 1.118 GHz-1.215 GHz in lower L band and a bandwidth of 1.55 GHz-1.61 GHz in the upper L band. In order to achieve a wide axial ratio bandwidth, a dual-feed mechanism utilizing a capacitively coupled probe feeding scheme is incorporated. The overall size of the proposed antenna is 100 mm by 100 mm. The measured results indicate an excellent correlation with simulations.
This paper introduces a novel planar super-wideband (SWB) antenna with reconfigurable band-notch characteristic. The antenna can work in band-notch mode or band-notch free mode. A good impedance matching is responsible for the SWB characteristic of the proposed antenna by adopting a gradient ground, a gradient feeder line, and a gradient radiating patch. Furthermore, to achieve a reconfigurable notched band function, a 0.3 mm deep slot which is 16 mm in length and 8 mm in width is dug near the antenna feeder for the placement of dielectric plates etched with different sizes of split ring resonator (SRR). The designed antenna has a size of 200 mm × 109 mm × 0.79 mm, and the measured frequency band of bandwidth covers 0.8-26 GHz with a reconfigurable band-rejection characteristic. The dielectric plates with different SRRs reject the part of WLAN band (5.44-5.55 GHz), X-band satellite downlink band (7.65 GHz-7.82 GHz), and 6.33 GHz-6.59 GHz. A good agreement is achieved within the super-wideband frequency range between simulated and measured results.