Showing papers on "Slot antenna published in 2015"
TL;DR: In this paper, the design of a four-band slot antenna for the global positioning system (GPS), worldwide interoperability for microwave access (WiMAX), and wireless area network (WLAN) is presented.
Abstract: The design of a four-band slot antenna for the global positioning system (GPS), worldwide interoperability for microwave access (WiMAX), and wireless area network (WLAN) is presented. The antenna consists of a rectangular slot with an area of ${\mathbf{0}}.{\mathbf{37}}{\lambda _g} \times {\mathbf{0}}.{\mathbf{14}}{\lambda _g} = {\mathbf{48}} \times {\mathbf{18}}\;{\bf m}{{\bf m}^{\mathbf{2}}}$ (where ${\lambda _g}$ is the guide wavelength), a $T$ -shaped feed patch, an inverted $T$ -shaped stub, and two $E$ -shaped stubs to generate four frequency bands. The radiating portion and total size of the antenna are less than those of the tri-band antennas studied in literature. Parametric study on the parameters for setting the four frequency bands is presented and hence the methodology of using the design for other frequency bands is proposed. The multiband slot antenna is studied and designed using computer simulation. For verification of simulation results, the antenna is fabricated and measured. The simulated and measured return losses, radiation patterns, realized peak gains, and efficiencies of the antenna are presented. Measured results show that the antenna can be designed to cover the frequency bands from 1.575 to 1.665 GHz for the GPS system, 2.4–2.545 GHz for the IEEE 802.11b&g WLAN systems, 3.27–3.97 GHz for the WiMAX system, and 5.17–5.93 GHz for the IEEE 802.11a WLAN system. The effects of the feeding cable used in measurement and of the cover are also investigated.
224 citations
TL;DR: In this paper, a very compact ultrawideband (UWB) multiple-input multiple-output (MIMO) antenna with high isolation is presented, consisting of two UWB slot antennas.
Abstract: A very compact ultrawideband (UWB) multiple-input multiple-output (MIMO) antenna with high isolation is presented in this letter. The proposed antenna, consisting of two UWB slot antennas, has a very compact size of $22 \times 26~\hbox{mm}^{2}$ , which is smaller than most of UWB antennas only with single antenna element. A T-shaped slot is etched on the ground to improve the impedance matching characteristic in the low-frequency and reduce the mutual coupling for the frequencies $ \geq 4~\hbox{GHz}$ . By etching a line slot to cancel out original coupling, isolation enhancement at the 3–4 GHz band is achieved. The antenna possesses a low mutual coupling of less than $ - 18~\hbox{dB}$ over the operating band from 3.1–10.6 GHz. The performance of this antenna both by simulation and by experiment indicates that the proposed antenna is a good candidate for UWB applications.
214 citations
TL;DR: Two flexible conformal 4 × 4 ultrawideband antenna arrays (single and dual polarization), in a format similar to that of a bra, were developed for a radar-based breast cancer detection system.
Abstract: Radar-based microwave imaging has been widely studied for breast cancer detection in recent times. Sensing dielectric property differences of tissues has been studied over a wide frequency band for this application. We design single- and dual-polarization antennas for wireless ultrawideband breast cancer detection systems using an inhomogeneous multilayer model of the human breast. Antennas made from flexible materials are more easily adapted to wearable applications. Miniaturized flexible monopole and spiral antennas on a 50-μm Kapton polyimide are designed, using a high-frequency structure simulator, to be in contact with biological breast tissues. The proposed antennas are designed to operate in a frequency range of 2–4 GHz (with reflection coefficient (S11) below –10 dB). Measurements show that the flexible antennas have good impedance matching when in different positions with different curvature around the breast. Our miniaturized flexible antennas are 20 mm × 20 mm. Furthermore, two flexible conformal 4 × 4 ultrawideband antenna arrays (single and dual polarization), in a format similar to that of a bra, were developed for a radar-based breast cancer detection system. By using a reflector for the arrays, the penetration of the propagated electromagnetic waves from the antennas into the breast can be improved by factors of 3.3 and 2.6, respectively.
213 citations
TL;DR: In this article, the authors proposed a new antenna structure based on a parasitic elliptical patch in the flare aperture to enhance the field coupling between the arms and produce stronger radiation in the end-fire direction.
Abstract: Herein, a new method for improving the directivity and bandwidth of the antipodal Vivaldi antenna structure is presented. The method is based on introducing a parasitic elliptical patch in the flare aperture to enhance the field coupling between the arms and produce stronger radiation in the endfire direction. This approach improves the directivity without compromising the low frequency performance and removes the need for electrically thin dielectric substrates. The proposed antenna structure including the feeding line and transition measures $140 \times 66 \times 1.5 \text{mm}^3$ and has a peak gain $> 0\;{\text{dBi}}$ over the 2–32 GHz frequency range and ${>} 10\;{\text{dBi}}$ over the 6–21 GHz range, which is an improvement to what has been reported for Vivaldi antennas with similar size.
183 citations
TL;DR: In this paper, a beam-switching antenna using active cylindrical slot frequency selective surface (ACSFSS) is presented, which is composed of an omnidirectional monopole antenna and the ACSFSS.
Abstract: A novel design for a beam-switching antenna using active cylindrical slot frequency selective surface (ACSFSS) is presented. The antenna system is composed of an omnidirectional monopole antenna and the ACSFSS, which employs a new technique of switching slot arrays. The ACSFSS is made up of 12 columns with 8 slots each, dividing the cylinder by 30 $^{\circ}$ . To steer the beam of the antenna the diodes are set off and on, so that the radiation pattern of the antenna is determined by the number of off state columns. To estimate the general dimension of the cylindrical FSS, an equivalent metallic reflector is introduced and optimized, and then parametric studies for the unit cell dimensions are discussed. The fabricated prototype works within the WLAN band, centered around 2.45 GHz, and can agilely select either a narrow-beam or wide-beam operating mode. Simulation and measurements confirm the operation of the ACSFSS antenna, with good matching and gain observed. In particular, the narrow-beam mode $-$ 3 dB beamwidth is 47 $^{\circ}$ which offers enhanced angular resolution compared with other reported beam-sweeping work.
172 citations
TL;DR: A novel dual-band, dual-polarized, miniaturized and low-profile base station antenna operating in the frequency bands of 820-960 and 1710-2170 MHz is designed that meets the stringent design requirements and also meets telecommunications industry standards.
Abstract: In this paper, a novel dual-band, dual-polarized, miniaturized and low-profile base station antenna operating in the frequency bands of 820–960 and 1710–2170 MHz is designed. Elements are arranged such that high-frequency elements are embedded in low frequency elements to reduce volume. A baffle is used to reflect the transmitted power density in the forward direction and also improve isolation between elements. Therefore, surrounding isolation baffles and rectangular baffles are appended around high-frequency elements and low-frequency elements, respectively. The diameter of the proposed antenna cover is only 200 mm, which is smaller than the existing antenna diameter of 280 mm. Compared with the other commonly used antennas, the proposed antenna also has some advantages such as concealment and low profile using a tubular form of radome, which can easily integrate the proposed antenna with the surrounding environment. The measured results verify that the proposed antenna meets the stringent design requirements: voltage standing wave ratio (VSWR) is less than 1.3, the isolation is greater than 30 dB, and the pattern parameters also meet telecommunications industry standards.
154 citations
TL;DR: It is demonstrated from electromagnetic (EM) simulation and measurement that the radiation patterns of the proposed antenna are successfully switched by the SPDT switch.
Abstract: In this paper, we propose a paper-based pattern switchable antenna system using inkjet-printing technology for bi-direction sensor applications. The proposed antenna system is composed of two directional bow-tie antennas and a switching network. The switching network consists of a single-pole-double-throw (SPDT) switch and a balun element. A double-sided parallel-strip line (DSPSL) is employed to convert the unbalanced microstrip mode to the balanced strip mode. Two directional bow-tie antennas have different radiation patterns because of the different orientation of the reflectors and antennas. It is demonstrated from electromagnetic (EM) simulation and measurement that the radiation patterns of the proposed antenna are successfully switched by the SPDT switch.
144 citations
TL;DR: In this article, a reflectarray antenna with improved performance is proposed to operate in dual-polarization and transmit-receive frequencies in Ku-band for broadcast satellite applications, which contains two orthogonal sets of four coplanar parallel dipoles printed on two surfaces, each set combining lateral and broadside coupling.
Abstract: A reflectarray antenna with improved performance is proposed to operate in dual-polarization and transmit–receive frequencies in Ku-band for broadcast satellite applications. The reflectarray element contains two orthogonal sets of four coplanar parallel dipoles printed on two surfaces, each set combining lateral and broadside coupling. A 40-cm prototype has been designed, manufactured, and tested. The lengths of the coupled dipoles in the reflectarray cells have been optimized to produce a collimated beam in dual polarization in the transmit and receive bands. The measured radiation patterns confirm the high performance of the antenna in terms of bandwidth (27%), low losses, and low levels of cross polarization. Some preliminary simulations at 11.95 GHz for a 1.2-m antenna with South American coverage are presented to show the potential of the proposed antenna for spaceborne antennas in Ku-band.
134 citations
TL;DR: In this paper, an exponential slot edge antenna (ESE-AVA) with improved radiative features is presented, which extends the low-end bandwidth limitation, mitigates the side and back lobe levels, corrects squint effect, and increases the main lobe gain.
Abstract: This letter presents an Exponential Slot Edge Antipodal Vivaldi Antenna (ESE-AVA), with improved radiative features as compared to the conventional Antipodal Vivaldi Antenna (AVA) design. It extends the low-end bandwidth limitation, mitigates the side and back lobe levels, corrects squint effect, and increases its main lobe gain. In order to confirm those features, a comparative study among the ESE-AVA, the low directivity conventional AVA and two popular modifications, regular slot edge (RSE) and the tapered slot edge (TSE) AVA is performed. A comparison between AVA and the proposed ESE-AVA at 6 GHz shows an improved gain of 8.3 dB, $-$ 15.5 dB of Side Lobe Level (SLL), and 0 degrees of main lobe squint (MLS), in contrast with 5 dB of gain, $ - 5~\hbox{dB}$ of SLL, and 5 degrees of MLS in the conventional AVA. By comparing the ESE-AVA with RSE-AVA and TSE-AVA, it was observed that its notches in exponential shape, similar to open the main radiator, besides mitigating the SLL also directs the E-fields distributions towards the main lobe. It reflects into a main lobe gain improvement.
130 citations
TL;DR: In this article, a simple multiband metamaterial-loaded monopole antenna suitable for wireless local area network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) applications is proposed.
Abstract: A simple multiband metamaterial-loaded monopole antenna suitable for wireless local area network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) applications is proposed in this letter. The rectangle monopole of the proposed antenna is originally designed to resonate at around 5.2 GHz. When the inverted-L slot is etched, the antenna produces a second resonance at around 4.1 GHz. Then, with the addition of the metamaterial reactive loading, the resonant frequency of the antenna will be shifted down, and a third resonance covering the 2.4-GHz band occurs. Consequently, the antenna can cover the 2.4/5.2/5.8-GHz WLAN and 2.5/3.5/5.5-GHz WiMAX bands with a very compact size of only $12.9 \times 6.5~\hbox{mm}^2$ . Monopole-like radiation patterns and acceptable gains and efficiencies have been obtained. Details of the antenna design as well as the experimental results are presented and discussed.
129 citations
TL;DR: A review of the designs, characteristics, and applications of crossed dipole antennas along with the recent developments of single-feed circularly polarized (CP) configurations is presented in this paper.
Abstract: Crossed dipole antennas have been widely developed for current and future wireless communication systems. They can generate isotropic, omnidirectional, dual-polarized (DP), and circularly polarized (CP) radiation. Moreover, by incorporating a variety of primary radiation elements, they are suitable for single-band, multiband, and wideband operations. This article presents a review of the designs, characteristics, and applications of crossed dipole antennas along with the recent developments of single-feed CP configurations. The considerations of profile miniaturization, radiation pattern control, bandwidth enhancement, and multiband operation are emphasized.
TL;DR: In this paper, a 2.45 GHz broadband rectenna using the grounded coplanar waveguide (GCPW) is proposed, which has good performances of broadband, high mw-dc efficiency and compact structure.
Abstract: This letter presents a compact 2.45 GHz broadband rectenna using the grounded coplanar waveguide (GCPW). A new broadband slot antenna fed by GCPW with a high gain of 10 dBi and a wide half-power beamwidth of 60 $^{\circ}$ is designed as the receiving antenna. By designing an input and an output impedance match network, a compact GCPW rectifying circuit based on the voltage doubler principle is proposed, which has broadband performance and is easy to be integrated with the novel GCPW antenna. The receiving antenna and the rectifying circuit are simulated and measured. The measured results of the rectenna agree well with those of the rectifying circuit, which validate the effectiveness of the design. The microwave-direct current (mw-dc) conversion efficiencies of the rectenna keep higher than 50% within the band from 2.2 to 2.6 GHz at 13 dBm received power on a $900\Omega $ load, and the highest efficiency is 72.5%. This rectenna has good performances of broadband, high mw-dc efficiency and compact structure.
TL;DR: In this paper, a high-efficiency transmit array antenna composed of four layers of double split ring slot elements is designed, manufactured, and tested at Ku-band, and the diameter of the transmitarray antenna is 6.76 wavelengths, and measured gain is 23.9 dB.
Abstract: This letter present a high-efficiency transmitarray antenna using a four-layer double split ring slot structure as the unit cell element. The transmission coefficient of the element at different incident angles is analyzed by Ansoft HFSS, and the results show that the element has the advantages of low transmission loss and less sensitivity to the incidence angle of the electric field. A high-efficiency transmitarray antenna composed of four layers of double split ring slot elements is designed, manufactured, and tested at Ku-band. The diameter of the transmitarray antenna is 6.76 wavelengths, and the measured gain is 23.9 dB. Radiation efficiency of 77.6% and aperture efficiency of 55% are achieved at a center frequency of 13.58 GHz in this design. The measured 1-dB and 3-dB gain bandwidths are 7.4% and 17.7%, respectively.
Patent•
02 Sep 2015TL;DR: In this paper, the bodies of the waveguides are formed by a resin molding method, and surface treatment is performed with respect to inner surfaces of the Waveguides with plating.
Abstract: An array antenna device includes a plurality of slot array antennas which are arranged and each of which includes a plurality of slot antennas and a radiation surface, which is formed to be conformal, and a plurality of waveguides each of which supplies respective power to each of the slot array antennas. After bodies of the waveguides are formed by a resin molding method, surface treatment is performed with respect to inner surfaces of the waveguides with plating.
TL;DR: In this paper, a new design approach for a microstrip patch antenna to achieve reconfigurable dual-band operation with tunable frequency ratio is introduced, which uses a lumped capacitor in the middle of a slotted patch antenna, which results in two resonant frequencies.
Abstract: A new design approach for a microstrip patch antenna to achieve reconfigurable dual-band operation with tunable frequency ratio is introduced. The approach uses a lumped capacitor in the middle of a slotted patch antenna, which results in two resonant frequencies. The two resonant frequencies and their ratio are functions of the capacitance value. If a varactor with an appropriate biasing network is used, electronic tuning is realized by changing the applied DC voltage. To understand the dual-resonance behavior of the proposed antenna, an equivalent circuit model based on the transmission line theory of the antenna is established, considering the slot effect and the lumped capacitor. The results are verified with full wave simulation. Furthermore, measurements for fabricated antenna prototypes operating in 2–4.5 GHz are carried out for validation, and the performance shows a tunable frequency ratio from 1.45 to 1.93 with a capacitance range from 0.31 to 0.74 pF. It is worthwhile to point out that the radiation patterns are similar at both bands because both resonances are due to the fundamental TM01 mode.
TL;DR: In this paper, a unit cell consisting of three thin metallic layers with air gap in between, without use of any dielectric substrate is presented, which leads to a high-efficient, wideband, and single-linear-polarized slot-based transmitarray antenna.
Abstract: A novel high-efficient, wideband, and single-linear-polarized slot-based transmitarray antenna is presented. The unit cell comprises three thin metallic layers with air gap in between, without use of any dielectric substrate. Each metallic layer has a square wide slot within which there are a number of parallel stubs. The wide slot has a high-pass response with notch at zero frequency. Addition of the stubs creates an extra controllable notch within the wide slot high-pass response. Due to the large spacing between the two notches, a passband with low-slope phase shift response is created which leads to a wideband transmitarray. The linear polarization behavior of the antenna along with a suitable feed horn and with no dielectric loss present has resulted in higher antenna efficiency. The design of a three metallic layer unit cell is also carried out through a simple circuit-based analysis approach. The transmitarray is fabricated and results are compared with those of simulation. The proposed transmitarray has a measured $- 1\;\text{dB}$ -gain bandwidth of 15.5%, peak efficiency of 55%, and a cross-polarization level of better than $-29\;\text{dB}$ . The structure is simulated via HFSS software and ADS package is used for equivalent circuit (EC) simulation.
TL;DR: In this paper, an equal-phase but unequal-power symmetric waveguide divider is proposed for constructing an amplitude-tapering feed-network for a low profile slot antenna array.
Abstract: A low profile slot antenna array is designed to operate over a wide bandwidth with low sidelobe levels. Taylor synthesis is used to taper the power distribution among array aperture. An efficient approach to design an equal-phase but unequal-power symmetric waveguide divider is proposed for constructing an amplitude-tapering feed-network for the array. Phase differences are balanced by adjusting the waveguide phase velocities. The basic radiator is a 2 $\,\times\,$ 2 slot subarray, uniformly fed by such a waveguide divider. A 16 $\,\times\,$ 16 array is then constructed by 8 $\,\times\,$ 8 of such subarrays. A 1-to-64 way corporate-feed waveguide network is designed to excite all subarrays instead of individual slots, and the required power distribution is obtained by adopting a 30 dB Taylor $\overline N=4$ synthesis. Measured results indicate that the array can achieve a 13.8% bandwidth and a gain of more than 29.5 dBi. The first sidelobe level is $ -26.5~{\rm dB} $ in the $E$ -plane and $ -30.4~{\rm dB} $ in the $H$ -plane. The holistic sidelobe levels in both planes are better than $ -25~{\rm dB} $ with a better than $ -40~{\rm dB} $ cross-polarization.
TL;DR: In this article, a novel center-fed wideband slotline antenna is proposed using the multi-mode resonance concept, where symmetrically introducing one or two pairs of slot stubs along the slotline resonator near the nulls of electric field distribution of the second odd-order mode, two modes are excited in a single slotline radiator.
Abstract: A novel center-fed wideband slotline antenna is proposed using the multi-mode resonance concept. By symmetrically introducing one or two pairs of slot stubs along the slotline resonator near the nulls of electric field distribution of the second odd-order mode, two modes are excited in a single slotline radiator. With the help of these stubs, the second odd-order mode can be gradually merged with its first counterpart, resulting in a wideband radiation characteristic with two resonances. Prototype antennas are then designed and fabricated to experimentally validate the principle and design approach. It is shown that the operation fractional bandwidth of the proposed slotline antenna could be effectively increased to 31.5% while keeping an inherent narrow slot structure.
TL;DR: In this paper, a compact antipodal Vivaldi antenna (AVA) with the dimension of $42 \times 36 \times 1.6~\hbox{mm}{^3}$ is proposed.
Abstract: A compact antipodal Vivaldi antenna (AVA) with the dimension of $42 \times 36 \times 1.6~\hbox{mm}{^3}$ is proposed in this letter. Structural modifications in the radiating fins have increased the electrical length thereby reducing the lower operating frequency from 5.2 GHz to 3.7 GHz. Proposed antenna maintains $-20~\hbox{dB}$ copolarization to cross-polarization ratio throughout the operating bandwidth. The prototype is fabricated and the measurement results are presented to validate the performance of the proposed AVA.
TL;DR: In this paper, a 77 GHz transmit-array on dual-layer printed circuit board (PCB) is proposed for automotive radar applications, where coplanar patch unit-cells are etched on opposite sides of the PCB and connected by through-via.
Abstract: A 77-GHz transmit-array on dual-layer printed circuit board (PCB) is proposed for automotive radar applications. Coplanar patch unit-cells are etched on opposite sides of the PCB and connected by through-via. The unit-cells are arranged in concentric rings to form the transmit-array for 1-bit in-phase transmission. When combined with four-substrate-integrated waveguide (SIW) slot antennas as the primary feeds, the transmit-array is able to generate four beams with a specific coverage of $\pm 15^{\circ}$ . The simulated and measured results of the antenna prototype at 76.5 GHz agree well, with gain greater than 18.5 dBi. The coplanar structure significantly simplifies the transmit-array design and eases the fabrication, in particular, at millimeter-wave frequencies.
TL;DR: This paper reviews 66 planar antenna designs, which includes 38-patch and 28-slot antennas, and provides an extensive qualitative comparison of these antennas in terms of their mass, size, gain, beam steerability, type of polarization, operating frequency band, and return loss.
Abstract: Works on pico-satellites have gained momentum recently, especially those that consider pico-satellites as part of a much larger constellation or swarm. This feature allows pico-satellites to provide high temporal resolution of observational data and redundancy. In particular, it reduces the need for satellite-to-ground communications and, hence, helps save energy and allows the execution of distributed processing algorithms on the satellites themselves. Consequently, satellite-to-satellite or cross-link communication is critical. To realize these advantages, the cross-link antenna employed on pico-satellites must meet many criteria, namely, small size, lightweight, low-power consumption, high gain, wide bandwidth, circular polarization, and beam steerability. To date, no works have examined the suitability of existing planar antenna designs for the use on pico-satellites. To this end, this paper contributes to the literature by focusing on microstrip patch and slot antennas that have the ability to achieve high gain, beam steering, and wide bandwidth. This paper reviews 66 planar antenna designs, which includes 38-patch and 28-slot antennas. In addition, we provide an extensive qualitative comparison of these antennas in terms of their mass, size, gain, beam steerability, type of polarization, operating frequency band, and return loss. In addition, we have evaluated three antenna designs that best address the pico-satellite challenges on a common platform. We find that the asymmetric E-shaped patch antenna design is the most suitable for the use on 2U CubeSats. This is because of its small size ( $34\times 13$ mm $^{2})$ and high gain (7.3 dB). In addition, the E-shaped patch antenna yields a wide −10-dB bandwidth of 2300 MHz and a small return loss of −15.2 dB.
TL;DR: In this paper, a compact circularly polarized slot antenna is proposed for universal ultra-high frequency (UHF) radio-frequency identification (RFID) reader applications, which has a much wider operation bandwidth compared to the antennas with similar sizes.
Abstract: A compact circularly polarized slot antenna is proposed this in communication, which has a much wider operation bandwidth compared to the antennas with similar sizes. This antenna is designed for universal ultrahigh frequency (UHF) radio-frequency identification (RFID) reader applications. The antenna is coplanar waveguide (CPW) fed by an L-shaped feeding line. To achieve good impedance matching and broadband CP operation, two L-shaped strip lines are inserted into the circular slot in the ground plane. The measured 10-dB return loss bandwidth is 380 MHz (618–998 MHz, 47.0% centered at 808 MHz). The measured 3-dB axial ratio bandwidth is about 332 MHz (791–1123 MHz, 34.7% centered at 957 MHz). The overall size of the antenna is ${120} \times {120} \times {0}.{8}\mathrm{m}{\mathrm{m}^{3}}$ .
TL;DR: In this article, an asymmetric cross-shaped metasurface (MS) was proposed to reconfigure the polarization of the slot antenna between RHCP, LHCP, and linear polarization.
Abstract: This letter presents a polarization-reconfigurable compact slot antenna with reduced radar cross section (RCS) using an asymmetric cross-shaped metasurface (MS). The proposed MS can reconfigure the polarization of the slot antenna between right-hand circular polarization (RHCP), left-hand circular polarization (LHCP), and linear polarization (LP) by rotating it with respect to the center of the slot antenna. In addition, the MS reduces the RCS of the slot antenna significantly in all polarization states. The cross-slot MS is placed just over the planar slot antenna without any air gap. The simulated monostatic RCS of $- $ 19.5 dBsm is observed at 4.4 GHz for LHCP and RHCP cases and $- $ 17.0 dBsm for LP mode of operation. Antenna performance in terms of its input matching, far-field parameters, monostatic RCS, and axial ratio are measured at its three polarization states, which are in agreement with simulated results.
TL;DR: In this article, a U-slot loaded single-layer half-width leaky-wave antenna (HW-MLWA) is proposed to achieve dual-band operation by periodically loading the antenna with U-shaped slots.
Abstract: Half-width microstrip leaky-wave antennas (HW-MLWAs) are generally single band. Here, we present a new method to achieve dual-band operation from an HW-MLWA by periodically loading the antenna with U-shaped slots. These dual-band MLWAs are able to steer the beam in forward directions in one band and in backward directions in the other band. One of the antenna designs was prototyped and tested, and excellent agreement between the predicted and measured results were observed. The measured 10-dB return loss bandwidth of the first and second bands are $19.5 \% $ (5.24–6.37 GHz) and $13.2 \% $ (7.9–9.02 GHz), respectively. The antenna can steer the main beam from $30^\circ $ to $65^\circ $ in the first band and from $-46^\circ $ to $-10^\circ$ in the second band by sweeping the frequency from 5.25 to 6.25 GHz and 7.75 to 9 GHz, respectively. The measured peak gain of the antenna is 12.2 and 14.1 dBi in the first and second bands, respectively. Although the antenna parameters are optimized for dual-band operation, the radiation properties in another higher frequency band (third band) are also explored. In the third band, the antenna beam continuously scans from backward to forward direction as frequency increases. Moreover, this U-slot loaded single-layer half-width LWA is easy to fabricate.
TL;DR: In this article, a 3D slot-rotated antenna for a microwave head- imaging system is presented, which is designed to have a wideband and unidirectional performance at the low microwave frequency band that are the requirements of the specified imaging system.
Abstract: A 3-D slot-rotated antenna for a microwave head- imaging system is presented. The antenna is designed to have a wideband and unidirectional performance at the low microwave frequency band that are the requirements of the specified imaging system. Starting from a traditional wide-slot antenna, several conventional techniques are applied to enhance its bandwidth and directivity while miniaturizing its size. In that regard, four series of staircase-shaped slots are applied to lower the operating frequency, whereas a folding process is used to enhance the directivity and reduce the overall size. In addition, two parasitic patches are connected to the slot area to increase the operating bandwidth. The final design has the dimensions of ${\hbox {0.11}} \lambda \times {\hbox {0.23}} \lambda \times {\hbox {0.05}} \lambda $ . ( $\lambda $ is the wavelength of the lowest measured operating frequency.) It has a measured VSWR fractional bandwidth of 87% (1.41–3.57 GHz) and a peak front-to-back ratio of 9 dB. To verify the suitability of the antenna in head imaging, it is connected to a wideband microwave transceiver and used to circularly scan an artificial head phantom in $20^\circ$ angle steps in a monostatic mode. The collected backscattered data are then processed and used to generate an image that successfully shows brain tumors. The compact size, wide operating bandwidth, unidirectional radiation, and detection viability are merits of the presented antenna and the subsequent system.
TL;DR: In this article, a folded reflectarray designed for Ka-band satellite communication applications is presented, where Vias are employed to suppress the surface wave propagation and reduce the mutual coupling between adjacent array elements, for achieving a reflectarray with a wide scan angle range.
Abstract: This paper presents a folded reflectarray designed for Ka-band satellite communication applications. The array element is a dual-polarized slot antenna with multilayered PCB structure and is designed to operate at 29.5–30.8 GHz band for both transmitting and receiving with single linear polarization. Vias are employed to suppress the surface wave propagation and reduce the mutual coupling between adjacent array elements, for achieving a reflectarray with a wide scan angle range. An equivalent circuit model for the array element is developed and it agrees well with the EM simulation results. Several passive demonstrators consisting of 116 elements spaced by $0.5{\lambda }_{30_{\rm{GHz}}}$ were fabricated and measured. The experimental results show that the presented reflectarray is capable of steering the beam up to $\pm 60^{\circ} $ in both E- and H-planes with low cross-polarization level.
TL;DR: In this article, a perforated metallic cap, forming a frequency-selective surface (FSS), over a printed-circuit-board (PCB) is proposed to enhance the V-band antenna in the form of a low profile Fabry-Perot cavity.
Abstract: Gain enhancement of a V-band planar antenna in the form of a low-profile Fabry-Perot cavity (FPC) is proposed. This simple design is based on placing a perforated metallic cap, forming a frequency-selective-surface (FSS), over a printed-circuit-board (PCB). An integrated slot-dipole antenna is etched in a thin layer of copper (the ground plane) printed on the other side of the PCB. The metallic cap is self-sustained with surrounded metallic sidewalls. Besides showing the simplicity of such design, we also provide a novel comprehensive analysis using a transmission-line model of a FPC along with the two-port circuit model of the thick FSS. The leaky-wave interpretation for the cavity radiation is also addressed to estimate the effective radiation area and therefore the size of the cap. It will be shown that placing the cap on top of the PCB, besides enhancing the directivity of the feeding-slot reduces its backward radiation. A FPC prototype operating in the 60 GHz wireless band, is fabricated and measured showing good agreement between the simulated and measured results.
19 Jul 2015
TL;DR: In this article, a dual-band printed slot antenna for future 5G mobile networks is proposed, which provides almost omni-directional patterns, relatively flat gain and high radiation efficiency through the frequency band excluding the rejected band.
Abstract: In this article, a dual-band printed slot antenna for the future fifth generation (5G) mobile networks are proposed. The antenna is compact with size of 0.8 λ 0 × 0.75 λ 0 at 28 GHz. Matching between a sector-disk shaped radiating patch and the 50-Ω microstrip line is manipulated through aproximity-feed technique. An elliptically shaped aperture is etched in the ground plane to enhance the antenna bandwidth. A shunt stub is used to get more enhancement of the impedance bandwidth of the antenna. To reduce the interference between the 5G system and other systems, π-shaped slot is etched off in the feed line to create a notched band of 30–34 GHz. The simulated results show that the designed antenna has a dual band function at 28/38 GHz that covers future 5G applications. The proposed antenna provides almost omni-directional patterns, relatively flat gain, and high radiation efficiency through the frequency band excluding the rejected band.
TL;DR: In this paper, a broadband artificial material composed of non-resonant parallel-line unit cells is proposed to enhance the gain of an antipodal tapered slot antenna (ATSA).
Abstract: A broadband artificial material composed of non-resonant parallel-line unit cells is proposed to enhance the gain of an antipodal tapered slot antenna (ATSA). The artificial material, whose effective refractive index is lower than that of the substrate on which the antenna is printed, will act as a regular lens in beam focusing. In order to investigate the gain enhancement effect of the material, a combination of the proposed material with an ATSA is made by locating the material in front of the antenna. Simulation results indicate that the gain of the antenna has been enhanced significantly and increasing the dimension of the material in the radiation direction leads to a higher gain without destroying its broadband characteristic. The original and the artificial material loaded ATSAs are designed and fabricated with the measurement results showing that the gain of the original ATSA has been increased by 1.3–3.6 dB in the measurement bandwidth of 6–19 GHz.
TL;DR: In this paper, a very small coplanar waveguide (CPW)-fed rectangular slot antenna with dual band-notched characteristics for super ultrawideband (UWB) applications is proposed.
Abstract: A very small coplanar waveguide (CPW)-fed rectangular slot antenna with dual band-notched characteristics for super ultrawideband (UWB) applications is proposed. This antenna consists of a rectangular slot, a beveled rectangular patch, two S-shaped slits cut in the ground plane and an elliptical ring slot (ERS) etched in the patch. The corners of a simple rectangular patch are beveled to improve the impedance bandwidth, especially at the middle frequencies of the band. In addition, a pair of semicircle slots is etched in the ground plane to enhance the bandwidth to more than 23 GHz. A pair of S-shaped slits connected to the rectangular slot, and an ERS cut in the beveled rectangular patch, is employed to create band-notched performances in WiMAX and WLAN spectrum, respectively. The proposed antenna has a very small size of $15 \times 15 \text{mm}^{2}$ , and therefore, it is one of the smallest UWB slot antennas that have been reported until now, and provide a very wide impedance bandwidth from 2.6 to more than 23 GHz for $\text{VSWR} with dual band-notched properties.