Showing papers on "Microstrip published in 2018"
TL;DR: In this article, a compact design of multiple-input multiple-output (MIMO) Antenna with dual sharply rejected notch bands for portable wireless ultrawideband (UWB) applications is presented and experimentally investigated.
Abstract: In this paper, a compact design of multiple-input multiple-output (MIMO) Antenna with dual sharply rejected notch bands for portable wireless ultrawideband (UWB) applications is presented and experimentally investigated. The proposed UWB MIMO Antenna has a compact size of 18 mm $\times$ 34 mm. The tapered microstrip fed slot Antenna acts as a single radiating element with inverted L-shaped slits to introduce notches at wireless local area network and the IEEE INSAT/Super-Extended C-bands. The mutual coupling of less than −22 dB is achieved over the entire operating band (2.93–20 GHz). At the center of notched band, the efficiency of the Antenna drops that indicates a good interference suppression performance. The performance of the MIMO Antenna in terms of isolation among the ports, radiation pattern, efficiency, realized gain, envelope correlation coefficient, mean effective gain, and total active reflection coefficient is studied.
213 citations
TL;DR: In this article, a microwave sensor using a pair of split-ring resonators (SRRs) is presented, which is designed by loading a microstrip transmission line by two identical SRRs on its sides.
Abstract: This paper presents a microwave sensor using a pair of split-ring resonators (SRRs). The sensor is designed by loading a microstrip transmission line by two identical SRRs on its sides. Differential permittivity sensing is performed by loading the SRRs with dielectric samples. One transmission notch is observed for the identical loads, whereas the non-identical samples produce two split notches. The sensor’s operating principle is described through a circuit model analysis. A prototype of the designed sensor is fabricated and experimentally validated for verifying the differential sensing concept. The developed device can be used to compare or differentially characterize solid dielectric samples improving the robustness to environmental factors producing cross-sensitivity or miscalibration.
192 citations
TL;DR: In this article, a Ka-band inset-fed microstrip patches linear antenna array is presented for 5G applications in different countries, which employs 16 elements in an H-plane new configuration.
Abstract: A Ka-band inset-fed microstrip patches linear antenna array is presented for the fifth generation (5G) applications in different countries. The bandwidth is enhanced by stacking parasitic patches on top of each inset-fed patch. The array employs 16 elements in an H-plane new configuration. The radiating patches and their feed lines are arranged in an alternating out-of-phase 180° rotating sequence to decrease the mutual coupling and improve the radiation pattern symmetry. A (24.4%) measured bandwidth (24.35–31.13 GHz) is achieved with −15 dB reflection coefficients and 20 dB mutual coupling between the elements. With uniform amplitude distribution, a maximum broadside gain of 19.88 dBi is achieved. Scanning the main beam to 49.5° from the broadside achieved 18.7 dBi gain with −12.1 dB sidelobe level. These characteristics are in good agreement with the simulations, rendering the antenna to be a good candidate for 5G applications.
154 citations
TL;DR: The structure of the proposed differential permittivity sensors based on a pair of uncoupled microstrip lines loaded with an open complementary split ring resonator is applied to monitor sodium content in aqueous solutions, and it is found that sodium concentrations as small as 0.25 g/L can be resolved.
Abstract: Differential permittivity sensors based on a pair of uncoupled microstrip lines, each one loaded with an open complementary split ring resonator (OCSRR), are proposed in this paper. The sensing principle is based on the measurement of the cross-mode insertion loss, very sensitive to asymmetric loading. Thus, by loading one of the OCSRRs with the reference sample, and the other one with the sample under test (SUT), the difference in the complex permittivity between both samples generates an asymmetry that gives rise to mode conversion. From the measurement of the cross-mode transmission coefficient, the dielectric properties of the SUT can be determined, provided those of the reference sample are well known. It is shown that by adding fluidic channels on top of the OCSRRs, the proposed sensor is useful for the measurement of the complex dielectric constant of liquids, and experimental results in mixtures of ethanol and deionized (DI) water and methanol in DI water, as a function of the ethanol/methanol content, are provided. Due to the high sensitivity of the proposed differential sensor to detect small perturbations (asymmetries), the structure is also of interest for the accurate measurement of solute concentrations in liquid solutions. In this paper, the structure is applied to monitor sodium content in aqueous solutions, and it is found that sodium concentrations as small as 0.25 g/L can be resolved.
145 citations
TL;DR: An overview of a new type of family of low-loss antennas and components based on the recently developed gap waveguide technology is presented and can be considered as a good candidate to be used as the core RF building block.
Abstract: Millimeter-wave communication systems require many innovative antennas adapted for future application scenarios such as the upcoming 5G cellular networks. Due to the strong path loss in free space at the millimeter-wave frequency range, high gain and low-cost antennas are in great demand. Also, advanced features such as multi-beam for multiple user, dual-polarization, or even complete phased arrays with enormous degrees of freedom in beamforming are some of the key research lines for antenna designers nowadays. In this article an overview of a new type of family of low-loss antennas and components based on the recently developed gap waveguide technology is presented. With the advent of new millimeter-wave applications, this low-cost and low-loss waveguide technology can be considered as a good candidate to be used as the core RF building block.
125 citations
TL;DR: The main advantage of this method, which is validated from the measurement of the complex dielectric constant of olive and castor oil, is that reference samples for calibration are not required.
Abstract: In this paper, an analytical method to estimate the complex dielectric constant of liquids is presented. The method is based on the measurement of the transmission coefficient in an embedded microstrip line loaded with a complementary split ring resonator (CSRR), which is etched in the ground plane. From this response, the dielectric constant and loss tangent of the liquid under test (LUT) can be extracted, provided that the CSRR is surrounded by such LUT, and the liquid level extends beyond the region where the electromagnetic fields generated by the CSRR are present. For that purpose, a liquid container acting as a pool is added to the structure. The main advantage of this method, which is validated from the measurement of the complex dielectric constant of olive and castor oil, is that reference samples for calibration are not required.
125 citations
TL;DR: In this article, a flexible ultrawideband (UWB) antenna is presented for wearable applications in the 3.7-10.3 GHz band, which is highly tolerant to human body loading and physical deformation.
Abstract: A new flexible ultrawideband (UWB) antenna is presented for wearable applications in the 3.7–10.3 GHz band, which is highly tolerant to human body loading and physical deformation. The antenna exhibits a footprint of 80 mm $\times$ 67 mm and is based on a simple microstrip structure with two modified arc-shaped patches as the main radiator. A full ground plane is maintained on the opposite side of the substrate to suppress antenna loading from the underlying biological tissues and back radiation directed toward the human body. For enhanced flexibility and robustness, the proposed antenna is realized using conductive fabric embedded into polydimethylsiloxane polymer. Promising simulation and experimental results are presented for free-space and in-vitro wearable scenarios. To our knowledge, this is the first UWB antenna with a full ground plane that is concurrently highly tolerant to harsh operating conditions, such as those encountered in wearable applications.
119 citations
TL;DR: In this paper, a simple technique is presented for the complete suppression of the open stopband in periodic leaky-wave antennas using two similar but non-identical elements per unit cell.
Abstract: A simple technique is presented for the complete suppression of the open stopband in periodic leaky-wave antennas using two similar but nonidentical elements per unit cell. With the technique, one needs only to optimize the distance between the two elements and the dimension of the second element, starting with a quarter of the period and the dimension of the first element. With the simple design procedure, the technique is practical and effective for the open-stopband suppression for various periodic leaky-wave antennas. Two periodic leaky-wave antennas with the technique are demonstrated. The first one is a new developed substrate-integrated waveguide antenna with two nonidentical transverse slots per unit cell. The antenna has a wide scanning range from the backward endfire to the forward direction and does not suffer from blind scanning points at endfires (if it is placed on an infinite ground plane). The antenna is theoretically investigated. The simulation and measured results are consistent with the theoretical results. The second one is a microstrip combline leaky-wave antenna, in which each unit cell contains two nonidentical open-ended stubs. The two examples validate that the technique proposed in this paper can completely eliminate the open stopband in periodic leaky-wave antennas.
116 citations
TL;DR: In this article, an electronically controllable microstrip leaky-wave antenna (LWA) is proposed to steer the radiations at a fixed frequency, which is composed of a corrugated microstrip line loaded by the varactor diodes with triangular-modulated surface impedance.
Abstract: An electronically controllable microstrip leaky-wave antenna (LWA) to steer the radiations at a fixed frequency is presented. The proposed LWA is composed of a corrugated microstrip line loaded by the varactor diodes with triangular-modulated surface impedance. Due to the periodical modulation of the surface impedance, the guided waves can be converted into the leaky-wave radiations efficiently with frequency-scanning property. Furthermore, the surface impedance of the LWA can be reconfigured by changing the capacitance of the varactor diode through dc bias voltage, which will make the radiation beam steer in a large angle range accordingly at a fixed frequency. Both numerical simulations and experimental results show that the radiation beams can be controlled for continuously steering at each frequency from 5.5 to 5.8 GHz by changing the dc bias voltage from 0 to 20 V, in which the scanning angle can reach as high as 45°.
106 citations
TL;DR: In this paper, the authors proposed a novel antenna system that combines the functionalities of TAs and RAs, which consists of a specially designed bifunctional metalens and a self-made Vivaldi antenna (feed source).
Abstract: The use of microstrip transmitarrays (TAs) and reflectarrays (RAs) is essential in long-range communication systems because of their high-gain radiations, narrow beam widths, simple configurations, and easy fabrication. We propose a novel antenna system that combines the functionalities of TAs and RAs. The antenna system consists of a specially designed bifunctional metalens and a self-made Vivaldi antenna (feed source). The metalens can focus the y-polarized incident wave at the transmission side and focus the x-polarized wave at the reflection side with the same focal length. By launching the metalens with differently polarized Vivaldi antennas, we were able to obtain a TA and RA. Moreover, the realized RA can deflect the radiation beam to a specified angle to avoid blockage of the feed antenna. Our numerical and experimental results coincided, indicating that the proposed antenna system demonstrated several improvements, including the ability to achieve multiradiation patterns, realize high gains, and adopt simple standard print circuit board technology. Our findings significantly expand the capabilities of metasurfaces in controlling electromagnetic waves and open up a new avenue for the design of high-performance multifunctional antenna systems and metadevices.
105 citations
TL;DR: In this article, a differential microwave permittivity sensor based on the reflection coefficient of microstrip lines terminated with series $LC$ resonators is presented, where two identical sensing elements are used for differential sensing, providing the possibility of simultaneous two samples detection.
Abstract: This letter presents a differential microwave permittivity sensor based on the reflection coefficient of microstrip lines terminated with series $LC$ resonators. A $50~\Omega $ resistor is considered in series with the resonator. At resonance, the transmission line experiences a matched load causing a reflection zero. Two identical sensing elements are used for differential sensing, providing the possibility of simultaneous two samples detection. A prototype of the sensor is fabricated and measured around 2 GHz for validation of the differential sensing principle.
TL;DR: System-level measurements prove the linearizability of the designed Doherty amplifier when a modulated signal is applied, and a simplified approach for the initial bandwidth estimation that requires linear simulations only is presented.
Abstract: This paper presents a novel technique for the design of broadband Doherty power amplifiers (DPAs), supported by a simplified approach for the initial bandwidth estimation that requires linear simulations only. The equivalent impedance of the Doherty inverter is determined by the value of the output capacitance of the power device, and the Doherty combiner is designed following this initial choice and using a microstrip network. A GaN-based single-input DPA designed adopting this method exhibits, on a state-of-the-art bandwidth of 87% (1.5–3.8 GHz), a measured output power of around 20 W with 6 dB back-off efficiency between 33% and 55%, with a gain higher than 10 dB. System-level measurements prove the linearizability of the designed Doherty amplifier when a modulated signal is applied.
TL;DR: The sensor structure described in this work is a compact, low-cost solution and has potential for further miniaturization in mobile applications which may serve as a method for pipeline breach detection.
Abstract: A planar microwave resonator sensor is designed, customized, and fabricated to detect coating breaches in industrial steel pipelines. The sensor, which utilizes a ring-shaped resonator to maximize the sensitivity at its core, is tuned to 2.5 GHz with a quality factor of 280. In the setup, the sensor is grounded to a piece of steel pipeline with an Epoxy-100 coating, which provides the substrate beneath the microstrip structure. It is demonstrated that any change in the gap height between the substrate layer and the pipeline, from 0 to 3.5 mm, produces a significant resonant frequency variation and bandwidth change in the sensor's response. The sensor structure demonstrates sensitivity and selectivity to air and water penetration to the breach. The sensor structure described in this work is a compact, low-cost solution and has potential for further miniaturization in mobile applications which may serve as a method for pipeline breach detection.
TL;DR: In this article, a dual-mode composite microstrip line (DMC-MSL) was proposed for the purpose of designing dual-band antennas and devices with a large frequency ratio.
Abstract: A dual-mode composite microstrip line (DMC-MSL) is reported in this paper for the purpose of designing dual-band antennas and devices with a large frequency ratio. The metallic strip of the conventional MSL is replaced with a substrate integrated waveguide (SIW) arranged into a thin dielectric laminate, which leads to that two modes operating in different frequency bands, i.e., the quasi-TEM mode and the TE10-like mode, can propagate along the transmission line structure simultaneously. The DMC-MSL with a dual-layered planar configuration combines the merits of the MSL and the SIW. In addition, by adjusting the permittivity of the dielectric laminate used for realizing the thin SIW, the frequency ratio of the two operating modes can be varied flexibly. Based on the DMC-MSL structure, a novel dual-band leaky-wave antenna is presented. Periodic parasitic microstrip patches and the transverse slot array etched on the SIW are introduced in order to generate the required spatial harmonics. A feed structure that can excite the two operating modes of the DMC-MSL separately is designed as well. The fabricated prototype verifies that backward and forward frequency-scanning radiation beams are achieved within the low-frequency band from 5.75 to 8.5 GHz and the high-frequency band from 35 to 41.5 GHz, respectively. The proposed DMS-MSL structure and the leaky-wave antenna offer a new mean to implement antennas and devices for microwave and millimeter-wave dual-band applications.
TL;DR: In this paper, a multi-band RF planar sensor is proposed for non-destructive testing of dispersive materials, which is based on a number of complementary split ring resonator (CSRR) unit cells etched in the ground plane of the microstrip line.
Abstract: In this paper, an attractive multi-band RF planar sensor, suitable for non-destructive testing of dispersive materials, is proposed. The proposed sensor is based on a number of complementary split ring resonator (CSRR) unit cells etched in the ground plane of the microstrip line. Each CSRR unit cell can be represented by a narrow band reject filter with its center frequency corresponding to the resonant frequency of the respective CSRR cell. The proposed technique is used to design the two, three and four band microwave sensors operating at 1.5 GHz, 2.45 GHz, 3.8 GHz, and 5.8 GHz. The distance between the two adjoining CSRRs is minimized for each case without appreciably increasing the inter-cell coupling effect. The transcendental equations required for determining the complex permittivity of the material under test in terms of the resonant frequency are derived from the numerical data obtained using the electromagnetic solver, the CST studio. These numerical equations are then used to obtain the dielectric properties of various test samples, which are measured using the vector network analyzer. The detailed air gap analysis is also performed for checking the accuracy of the designed planar sensor under the real situation. The proposed sensors are fabricated on 0.8 mm thick FR4 substrates using the standard photolithography technique. A number of standard samples are tested using the fabricated sensors in multiple frequency bands, and a good agreement between the obtained results and the data available in literature shows the applicability of the proposed scheme.
TL;DR: Two novel microstrip patch antennas with multiple parasitic patches and shorting vias have been presented for the bandwidth enhancement, which achieves a measured 10-dB impedance bandwidth of 17.4% from 5.5 to 6.55 GHz.
Abstract: Two novel microstrip patch antennas with multiple parasitic patches and shorting vias have been presented for the bandwidth enhancement. Based on the conventional triangular patch antenna, two more resonances can be obtained with the introduction of multiple parasitic patches, and consequently, the antenna bandwidth can be broadened. Parametric analysis of the patches has been studied for the verification of bandwidth enhancement. An example of the proposed antenna with multiple parasitic patches is designed, fabricated, and tested. The measured bandwidth with $\vert S_{11}\vert dB ranges from 5.46 to 6.27 GHz (13.8%), and good far-field radiation patterns can be obtained within the frequency band. In addition, two shorting vias are inserted into the above proposed antenna to decrease the input impedance, resulting in further bandwidth enhancement of the antenna. This antenna is fabricated and tested as well, which achieves a measured 10-dB impedance bandwidth of 17.4% from 5.5 to 6.55 GHz.
TL;DR: It is demonstrated directly that topological interfacial electromagnetic waves launched by a linearly polarized dipole source propagate in opposite directions according to the sign of the orbital angular momentum.
Abstract: New structures with richer electromagnetic properties are in high demand for developing novel microwave and optic devices aimed at realizing fast light-based information transfer and information processing. Here we show theoretically that a topological photonic state exists in a hexagonal LC circuit with short-range textures in the inductance, which is induced by a band inversion between p- and d-like electromagnetic modes carrying orbital angular momentum, and realize this state experimentally in planar microstrip arrays. Measuring both amplitude and phase of the out-of-plane electric field accurately using microwave near-field techniques, we demonstrate directly that topological interfacial electromagnetic waves launched by a linearly polarized dipole source propagate in opposite directions according to the sign of the orbital angular momentum. The open planar structure adopted in the present approach leaves much room for including other elements useful for advanced information processing, such as electric/mechanical resonators, superconducting Josephson junctions and SQUIDs.
TL;DR: In this paper, a 42-element microstrip parasitic patch antenna is developed in the millimeter-wave band for fifth-generation mobile communication base stations, which has an insertion loss of 0.045 dB.
Abstract: A 42-element microstrip parasitic patch antenna is developed in the millimeter-wave band for fifth-generation mobile communication base stations. A metalized elliptical stripline-to-embedded-microstrip transition with adaptive via-hole arrangement as well as a 20 dB Chebyshev tapered six-way power divider is proposed to have an insertion loss of 0.045 dB. To confirm the feasibility of the antenna, it has been measured to provide a 6.3% fractional bandwidth from 26.83 to 28.56 GHz at VSWR of less than 1.96. The array antenna gains of more than 21.4 dBi have been realized with sidelobe levels of better than –19.1 dB, operating within 27.5–28.5 GHz in both the azimuth and elevation directions.
TL;DR: In this paper, a unit cell based on a wideband bandpass filter is developed and applied to the design of the wideband transmitarray (TA) which consists of two identical trilayer frequency selective surfaces (FSSs).
Abstract: This letter presents a wideband transmitarray (TA) with reduced profile. A novel unit cell based on a wideband bandpass filter is developed and applied to the design of the TA. The TA consists of two identical trilayer frequency selective surfaces (FSSs), thus it has a lower profile compared to traditional designs that use at least four FSS layers separated by quarter-wavelength air gaps to obtain the $\text{360}^\circ $ phase shift range. The FSS has a pair of square patches printed on the top and bottom layers, and a square slot loaded by four microstrip lines printed on the middle layer. The phase shift is achieved by simultaneously adjusting the size of the square patches. Within the frequency band of interest, the developed unit cell shows low insertion loss and sufficient phase shift range. An equivalent circuit model is developed to better understand the operating principles of the FSS. To validate the design concept, one prototype operating at 13.5 GHz is designed, fabricated, and measured. The measurement results show that the designed TA achieves $ {\text{16}}\%$ 1 dB gain bandwidth and $ {\text{60}}\%$ aperture efficiency. The developed unit cell has symmetric configurations so it can also be applied to the design of dual-polarized or circularly polarized TAs.
TL;DR: In this article, a substrate integrated waveguide (SIW)-based LWA is described to overcome the open stopband (OSB) problem and provide beam scanning continuously from the backward to the forward direction from a conventional periodic LWA.
Abstract: For many leaky-wave antennas (LWAs), it is challenging to realize beam scanning through broadside. A problem is the presence of an open stopband (OSB), which restricts radiation in the broadside direction. In this paper, a novel substrate integrated waveguide (SIW)-based LWA is described to overcome the OSB problem and provide beam scanning continuously from the backward to the forward direction from a conventional periodic LWA. It is demonstrated that the $n =-1$ spatial harmonic can be excited efficiently from an SIW LWA and enables broadside radiation. However, it was found in our initial design that when the beam scans through the broadside, the cross-polarization level increases significantly compared to the beam close to the backfire direction. A technique is developed to reduce the cross-polarization level. As a result, a new antenna configuration is created. The antenna design has been realized and measured to validate the concept. The measured beam scanning range of the prototype is from −74° to +45° (119° of beam scanning) when the frequency sweeps from 7.625 to 11 GHz, and the measured cross-polarization level is 20.8 dB low at the main beam direction for the broadside beam.
TL;DR: In this article, a single-polarized filtering dielectric resonator antenna (DRA) with high selectivity is investigated, where the DRA is fed by hybrid microstrip line/conformal strip, excited in its fundamental TE$1\delta 1}^{y} $ mode.
Abstract: A compact single-polarized filtering dielectric resonator (DR) antenna (DRA) with high selectivity is investigated. The DRA is fed by hybrid microstrip line/conformal strip, excited in its fundamental TE $_{1\delta 1}^{y} $ mode. Owing to different loading effects of the microstrip stub and conformal strip, the resonance frequency of TE $_{1\delta 1}^{y}$ mode excited by the two feed lines is slightly different. Such stepping resonances yield a wide bandwidth of 21.9% and a very flat gain of 5.1 dBi. The hybrid-feeding scheme also establishes a cross-coupled structure in the DRA, which introduces two radiation nulls right near the band edges. A compact wideband filtering DRA (FDRA) with quasi-elliptic bandpass response is, therefore, obtained without requiring any specific filtering circuit. This single-polarized design is also modified to realize a dual-polarized FDRA by adding another orthogonal port with the same feeding scheme. To reduce mutual coupling between the two ports, the microstrip stubs are folded to L shape, and four additional metal posts are inserted into the DR. As a result, the isolation is improved by 14 dB, from 7.2 to 21.2 dB.
TL;DR: This work is partially supported by the Innovation Programme under grant agreement H2020-MSCA-ITN-2016SECRET-722424 and the financialsupport from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1.
Abstract: The paper presents a technique to enhance the isolation between adjacent radiating elements which is common in densely packed antenna arrays. Such antennas provide frequency beam-scanning capability needed in Multiple-Input Multiple-Output (MIMO) systems and Synthetic Aperture Radars (SARs). The method proposed here uses a metamaterial decoupling slab (MTM-DS), which is located between radiating elements, to suppress mutual-coupling between the elements that would otherwise degrade the antenna efficiency and performance in both the transmit and receive mode. The proposed MTM-DS consists of mirror imaged E-shaped slits engraved on a microstrip patch with inductive stub. Measured results confirm over 9–11 GHz with no MTM-DS the average isolation (S12) is -27 dB; however, with MTM-DS the average isolation improves to -38 dB. With this technique the separation between the radiating element can be reduced to 0.66λo, where λ0 is free space wavelength at 10 GHz. In addition, with this technique there is 15% improvement in operating bandwidth. At frequencies of high impedance match of 9.95 GHz and 10.63 GHz the gain is 4.52 dBi and 5.40 dBi, respectively. Furthermore, the technique eliminates poor front-to-back ratio encountered in other decoupling methods. MTM-DS is also relatively simple to implement. Assuming adequate space is available between adjacent radiators the MTM-DS can be fixed retrospectively on existing antenna arrays, which makes the proposed method versatile.
TL;DR: In this paper, the authors proposed a balanced quasi-absorptive single/dual-band bandpass filter (BPF) with symmetrical quasi-reflectionless differential-mode behavior.
Abstract: Microwave planar balanced single-/dual-band bandpass filters (BPFs) with symmetrical quasi-reflectionless differential-mode behavior are presented in this letter. They are made up of a direct single-/dual-band BPF branch with virtually short-ended stubs in differential-mode operation, whose input and output accesses are loaded with stub-loaded-type single-/dual-band bandstop filter (BSF) branches that are terminated with a resistor. These BSF branches exhibit a quasi-complementary transfer function with regard to the one of the BPF branch and absorb the differential-mode input-signal energy not transmitted by the filter to achieve quasi-reflectionless capabilities. The theoretical foundations of the proposed balanced quasi-absorptive single-/dual-band BPFs and synthesis examples are given. Furthermore, for experimental-demonstration purposes, microstrip prototypes of 3-GHz second-order single-band and 2.85/3.15-GHz first-order dual-band BPFs are manufactured and characterized.
TL;DR: In this paper, a low-cost, high-gain millimeter-wave antenna is proposed for 5G cellular applications. But the antenna is a 6 × 5 proximity-coupled planar array.
Abstract: A novel low-cost, high-gain millimeter-wave antenna has been presented. The antenna is a 6 × 5 proximity-coupled planar array suitable for 5G cellular applications. Good agreement between simulated and measured results achieved shows that the proposed antenna structure is efficient in achieving broadband characteristics and low sidelobe levels with a compact size. The antenna has a gain of 21 dBi over a bandwidth of 27.5–28.5 GHz. It also exhibits an impedance bandwidth of 9.8% from 26.04 to 28.78 GHz.
TL;DR: In this article, a 360° beam steering patch antenna with parasitic elements is presented, which consists of a radiating patch and six parasitic elements, each of which is connected through a group of shorting vias controlled by p-i-n diode switches.
Abstract: A novel 360° beam steering patch antenna with parasitic elements is presented in this paper. The designed antenna consists of a radiating patch and six parasitic elements, each of which is connected through a group of shorting vias controlled by p-i-n diode switches. By switching on the desired groups of the shorting vias, the electric field distribution inside substrate cavity appears at the desired beam direction. Rotationally switching on the groups of the shorting vias, the performance of 360° beam scanning is realized. To further understand operating mechanism, the antenna is modeled with equivalent circuit in terms of the on and off status of a sector of the antenna, which can be used as a design guide for shorting-vias-controlled reconfigurable microstrip patch antennas. The fabricated antenna achieves a bandwidth of 14.5%, a peak gain of 10 dBi, and the efficiency of 80.5%. The achieved beamwidths are 42° and 97° in azimuth and elevation planes, respectively. With an ability of being steered around zenith axis at six directions, the scanned beam range covers the entire 360°. The physical dimension is only $2.5\lambda _{g}$ for the size and $0.5\lambda _{g}$ for the profile. This antenna operates from 5.1 to 5.9 GHz and has significant meaning in the IEEE 802.11ac wireless local area network applications due to its capabilities of generating 360° steered beams.
TL;DR: In this paper, a planar microstrip meander SWS on a dielectric substrate at 50-70 GHz was studied. And the basic electromagnetic parameters of the SWS were calculated.
Abstract: Slow-wave structure (SWS) is a core part of a traveling-wave-tube (TWT) amplifier. In this letter, the planar microstrip meander SWS on a dielectric substrate at $V$ -band (50–70 GHz) is studied. The basic electromagnetic parameters of the SWS are calculated. The SWS circuits are designed and fabricated, and good transmission characteristics are measured. The SWS developed is characterized by a wide bandwidth and a relatively-large slow-wave factor, and is suitable for a low-voltage TWT with the sheet electron beam.
TL;DR: In this article, a single-layer circularly polarized array antenna is proposed in the context of the so-called gap waveguide (GW) technology, which combines the corporate-feeding network and the radiating apertures over one single layer.
Abstract: A single-layer circularly polarized array antenna is proposed in the context of the so-called gap waveguide (GW) technology. This ultracompact antenna combines the corporate-feeding network and the radiating apertures over one single layer, standing out among other solutions proposed so far in this technology. Apertures are backed by chamfered cylindrical cavities and are fed through a corporate feeding network, which combines both groove and ridge GWs. Cavities are naturally integrated within the bed of nails hosting grooves and ridges, leading to a very low-profile $4\times 4$ array. Experimental results are presented to confirm the good radiation performance obtained by simulations. The proposed array architecture may be seamlessly enlarged to any size thanks to the scalability of the gap-based corporate feeding network, making this solution very attractive for medium to high-gain applications.
TL;DR: In this article, a wideband circularly polarized (CP) antenna array composed of novel microstrip antenna elements is presented for IEEE 802.11 aj (45 GHz) application, achieving an impedance bandwidth of 24.9% and a 3 dB axial ratio (AR) bandwidth of 17.3%.
Abstract: A wideband circularly polarized (CP) $4 \times 4$ millimeter-wave antenna array composed of novel microstrip antenna elements is presented for IEEE 802.11 aj (45 GHz) application. Through introducing the L-shaped branches and truncated corners to the microstrip antenna element, an impedance bandwidth of 24.9% and a 3 dB axial ratio (AR) bandwidth of 17.3% are achieved. To clarify the effects of the L-shaped branches and truncated corners, the phase difference and amplitude ratios of the 180° and 90° electric field components at the point of (0,0,r) are extracted and analyzed. A simple and compact microstrip feeding network is designed to excite the CP antenna array, and two-layer PCB boards are used to implement the proposed array. The electromagnetic energy is coupled to the radiators from the feeding network through the aperture etched on the middle ground. The measured 3 dB AR bandwidth of the antenna array is 16% from 41.9 to 49.1 GHz, and the measured gain is all greater than 17 dBic within the band from 41 to 49 GHz.
TL;DR: In this paper, a planar ultrawideband Vivaldi antenna for base-station pattern diversity applications is presented, which is designed to cover most of the cellular and LTE bands, a very wide frequency range from 0.7 to 2.7 GHz.
Abstract: This letter describes a planar ultrawideband Vivaldi antenna for base-station pattern diversity applications. It is designed to cover most of the cellular and LTE bands, a very wide frequency range from 0.7 to 2.7 GHz. It is formed by two adjacent Vivaldi tapered slots with a rotated angle of 29° between them. The antenna is miniaturized by sharing some common structure and cutting the noncritical board area. It is designed step by step from a single Vivaldi element with a microstrip line feeding to a dual-slot pattern diversity radiator with uniform radiation patterns. It is fabricated and tested inside a near-field chamber. The radiation performance, including both in-phase and 180° out-of-phase differential feeding cases, is verified by simulation as well as experiment. The measured results show good agreement with the simulation. It could be useful for base station and other smart array systems.
TL;DR: In this article, a dual band-notched ultra wideband (UWB) multiple-input multiple-output (MIMO) antenna of size 22.26 × 26.0 × 0.8mm 3 is proposed for portable devices.
Abstract: In this paper, a novel compact dual band-notched ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna of size 22 × 26 × 0.8 mm 3 is proposed for portable devices. The antenna comprises of two stepped slot UWB antennas fed by 50 ohms microstrip line, T-shape slot and narrow slot. Dual band-notches from 5.4 to 5.86 GHz and 7.6–8.4 GHz are achieved by loading trident-shape strips on microstrip line. A T-shape slot is used on the ground plane to enhance impedance matching characteristics and to minimize mutual coupling above 4 GHz. To improve isolation further at 3–4 GHz, a narrow slot is used on ground. The proposed antenna is giving a good bandwidth ranging from 3.1 to 11.8 GHz with |S 11 | > 10 dB and mutual coupling larger than 20 dB in the entire operating band except at two rejected bands. The simulation and measurement results demonstrate that the antenna is more suitable for portable device applications.