Showing papers on "Folded inverted conformal antenna published in 2017"

A Dual-Band Inverted-F MIMO Antenna With Enhanced Isolation for WLAN Applications

Abstract: This letter presents a dual-band inverted-F multiple-input-multiple-output (MIMO) antenna with improved isolation, covering the 2.4/5-GHz wireless local networks (WLAN) band. The proposed MIMO antenna is composed of two symmetrical winding inverted-F antenna elements. The two antenna elements are closely spaced with about 0.115 λ 0 of the lower band. The high isolation is achieved by building two decoupling devices, a meandering resonant branch and an inverted T-shaped slot etched on the ground for the higher band and the lower band, respectively. Furthermore, two U-shaped slits achieving better impedance matching are etched on the 50-Ω feeding lines to broaden the bandwidth of the high band. The impedance bandwidth (S 11 <; -10 dB) of the proposed antenna covers 2.4-2.48 GHz in the lower band and 5.15-5.825 GHz in the upper band, and the proposed configuration obtains 15-dB isolation within the 2.4- and 5-GHz WLAN bands, which shows a significant improvement compared to the initial design of the MIMO antenna. The simulation and measurement results indicate that the proposed inverted-F MIMO antenna system is quite suitable for WLAN applications.

A Low-Profile Aperture-Coupled Microstrip Antenna With Enhanced Bandwidth Under Dual Resonance

Abstract: A low-profile aperture-coupled microstrip patch antenna (MPA) using the TM10 and TM30 resonant modes to enhance the impedance bandwidth is proposed in this paper. Based on the cavity model for a square MPA, the TM10 and TM30 modes as well as both higher odd-order and even-order modes between them can be characterized. In order to combine the dual radiative resonant modes for a wide impedance bandwidth, a rectangular radiating patch with an aperture-coupled feeder is employed and theoretically investigated at first, aiming to demonstrate that all of the undesired modes between them can be removed effectively. After that, by loading the shorting pins properly underneath the patch, the resonant frequency of TM10 mode is shown to progressively turn up with slight effect on that of TM30 mode. As a result, these two radiative modes can be allocated in proximity to each other, resulting in a wide impedance bandwidth with a stable radiation pattern and the same far-field polarization. Moreover, the principal parameters of the MPA have been extensively studied in order to investigate the sensitivity in input impedance of the aperture-fed patch antenna. Finally, the proposed antenna is fabricated and measured. Simulated and measured results are found in good agreement with each other and illustrate that the antenna achieves a wide impedance bandwidth of about 15.2% in fraction or 2.32–2.70 GHz under $\vert \text{S}_{\mathrm {\mathbf {11}}}\vert dB, while keeping a low profile property with the height of 0.032 free-space wavelength. Besides, a stable gain varied from 3 to 6.8 dBi within the whole operating band is also obtained.

A Differential-Fed Microstrip Patch Antenna With Bandwidth Enhancement Under Operation of TM 10 and TM 30 Modes

Abstract: A differential-fed microstrip patch antenna (MPA) with bandwidth enhancement is proposed under the operation of TM10 and TM30 resonant modes in a single patch resonator. Initially, a rectangular differential-fed MPA is theoretically investigated so as to demonstrate that all of the undesired modes between the TM10 and TM30 modes are suppressed or removed out effectively. Then, by symmetrically introducing two pairs of shorting pins, the resonant frequency of TM10 mode is progressively turned up. After that, with the help of two long slots, the resonant frequency of TM30 mode is decreased with slight effect on that of TM10 mode. Furthermore, a short slot is inserted at the center of the patch to cancel the parasitic inductances of the shorting pins and probe feeds. With this arrangement, these two radiative resonant modes are moved in proximity to each other for wideband antenna. Finally, the proposed differential-fed MPA is fabricated and measured. Experimental results illustrate that the impedance bandwidth ( $\vert S_{{{\text {dd}11}}}\vert dB) of the antenna has gained a tremendous increment up to about 13% (1.88–2.14 GHz), while keeping a low profile property with the height of 0.029 free-space wavelength. Additionally, the antenna has achieved a stable gain varied from 5.8 to 7 dBi over the operating band.

Mutual Coupling Reduction in Microstrip Patch Antenna Arrays Using Parallel Coupled-Line Resonators

Abstract: This letter presents the implementation of a pair of parallel coupled-line resonators (PCRs) for isolation enhancement in planar microstrip patch array antennas. Each PCR consists of three coupled lines separated by a small coupling distance. The attempted configuration provides band-reject characteristics at the design frequency of 3.5 GHz. Two such PCRs are replicated to provide higher order rejection that enhances the bandstop characteristics. The designed PCR is deployed in a two-element microstrip patch antenna array, and the mutual coupling characteristics are studied. The proposed PCR-based decoupling unit cell provides additional 12–26.2-dB coupling reduction with an enhancement of antenna gain up to 1.25 dB. The prototype antenna is fabricated, and the simulation results are validated using experimental measurements.

A Wideband Circularly Polarized Conformal Endoscopic Antenna System for High-Speed Data Transfer

Abstract: In this paper, a conformal wideband circularly polarized (CP) antenna is presented for endoscopic capsule application over the 915-MHz Industrial, Scientific, and Medical (902–928 MHz) band. The thickness of the antenna is only 0.2 mm, which can be wrapped inside a capsule’s inner wall. By cutting meandered slots on the patch, using open-end slots on the ground, and utilizing two long arms, the proposed antenna obtains a significant size reduction. In the conformal form, the antenna volume measures only 66.7 mm3. A single-layer homogeneous muscle phantom box is used for the initial design and optimization with parametric studies. The effect of the internal components inside a capsule is discussed in analyzing the antenna’s performance and to realize a more practical scenario. In addition, a realistic human body model in a Remcom XFdtd simulation environment is considered to evaluate the antenna characteristics and CP purity, and to specify the specific absorption rate limit in different organs along the gastrointestinal tract. The performance of the proposed antenna is experimentally validated by using a minced pork muscle phantom and by using an American Society for Testing and Materials phantom immersed in a liquid solution. For measurements, a new technique applying a printed 3-D capsule is devised. From simulations and measurements, we found that the impedance bandwidth of the proposed antenna is more than 20% and with a maximum simulated axial ratio bandwidth of around 29.2% in homogeneous tissue. Finally, a wireless communication link at a data rate of 78 Mb/s is calculated by employing link-budget analysis.

Design of filtering microstrip antenna array with reduced sidelobe level

Abstract: For the requirements of efficient integration and simple fabrication, a new codesign approach for a microstrip filter with an antenna array with reduced sidelobe level is introduced in this communication. The microstrip patch antennas and the stub-loaded resonators are used to illustrate the synthesis of a bandpass filtering antenna array. By controlling the coupling strength between the resonators, a uniform or nonuniform power divider network can be obtained. A nonuniform power division is used to reduce the sidelobe level. The equivalent lumped circuit model is developed and analyzed in detail. Two types of eight-element filtering antenna array with uniform and tapered power-distribution among the elements have been designed. Simulated and measured results provide a good verification for the theoretical concepts.

Design and Fabrication of a High-Gain 60-GHz Cavity-Backed Slot Antenna Array Fed by Inverted Microstrip Gap Waveguide

Abstract: This communication deals with the design of a $16\times 16$ slot array antenna fed by inverted microstrip gap waveguide (IMGW). The whole structure designed in this communication consists of radiating slots, a groove gap cavity layer, a distribution feeding network, and a transition from standard WR-15 waveguide to the IMGW. First, a $2\times 2$ cavity-backed slot subarray is designed with periodic boundary condition to achieve good performances of radiation pattern and directivity. Then, a complete IMGW feeding network with a transition from WR-15 rectangular waveguide to the IMGW has been realized to excite the radiating slots. The complete antenna array is designed at 60-GHz frequency band and fabricated using Electrical Discharging Machining Technology. The measurements show that the antenna has a 16.95% bandwidth covering 54–64-GHz frequency range. The measured gain of the antenna is more than 28 dBi with the efficiency higher than 40% covering 54–64-GHz frequency range.

Broadband Filtering Dielectric Resonator Antenna With Wide Stopband

Abstract: A low profile stacked dielectric resonator antenna (DRA) and a microstrip metasurface (MS) antenna are investigated and compared in this communication. It has been found that very similar radiation performance including resonant modes, reflection coefficients, boresight gains, and radiation patterns can be obtained between them, indicating that the dielectric superstrate of stacked DRA plays analogous role with MS in enhancing the antenna bandwidth and realized gain. Based on this observation, a broadband, low profile, and high gain filtering cylindrical stacked DRA is inspired by an MS-based filtering antenna. Four resonant modes including the higher order HEM $_{31\delta }$ mode and HEM $_{13\delta }$ mode are simultaneously excited in the DRA to provide a broad bandwidth of 61.4% and a peak gain of 11.4 dBi within passband, whereas a shorting via and two pairs of transverse stubs are introduced into the feeding microstrip line to generate radiation nulls in stopband and realize filtering function. Second harmonic suppression has been achieved without increasing the footprint of the antenna, and an out-of-band suppression of more than 23 dB is obtained within the wide stopband.

Wideband Shorted Patch Antenna Under Radiation of Dual-Resonant Modes

Abstract: A novel design concept of enhancing the impedance bandwidth of a single-layer shorted microstrip patch antenna (MPA) is proposed under simultaneous radiation of the one- and three-quarter wavelength resonant modes (TM0,1/2 and TM0,3/2 modes). Initially, a conventional MPA with the shorting wall is studied to demonstrate that none of the redundant modes can be excited between the dual-resonant modes. Then, a pair of shorting pins are appropriately installed underneath the patch to progressively turn up the resonant frequency of TM0,1/2 mode without significant influence on that of TM0,3/2 mode. After that, a V-shaped slot is etched out on the patch to dramatically reduce the resonant frequency of TM0,3/2 mode with little effect on that of TM0,1/2 mode. With the use of these arrangements, the dual-desired radiative resonant modes are gradually moved in proximity to each other, thus widening the impedance bandwidth under emergence of dual resonant poles. In order to validate the principle and design method, the proposed antenna is designed, fabricated, and measured. The measured results demonstrate that the impedance bandwidth of the proposed shorted patch antenna has been extended to about 11.8%, and it is about 1.82 times of 6.5% of the traditional shorted MPA. Meanwhile, the fabricated antenna exhibits other attractive performances including stable radiation pattern, same polarization, and a low-profile property with the height of 0.042 free-space wavelength.

Design of a compact U-shaped slot triple band antenna for WLAN/WiMAX applications

Abstract: This article presents a small, low-profile planar microstrip antenna that is applicable for both WLAN and WiMAX applications. The goal of this paper is to design an antenna which can excite triple-band operation with appreciable impedance bandwidth to combine WLAN/WiMAX communication specifications simultaneously in one device. The designed antenna has a compact size of 10 × 26 mm 2 . The proposed antenna consists of an inverted U-shaped slot radiator and a defected ground plane. Overall the design method and parametric study found appropriate dimensions, which provides three distinct bands I from 2.40 to 2.52, II from 3.40 to 3.60 and III from 5.00 to 6.00 GHz that covers entire WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5) bands. Finally, a prototype antenna was fabricated and experimentally characterized to verify the design concept as well as to validate the simulation results. Thus the simulation results along with the measurements show that the antenna can simultaneously operate over WLAN and WiMAX frequency bands.

Design a single band microstrip patch antenna at 60 GHz millimeter wave for 5G application

Abstract: This proposed paper, a single band microstrip patch antenna for 5G wireless application is presented. This proposed antenna is suitable for the millimeter wave frequency. The single band antenna consist of new H slot and E slot loaded on the radiating patch with the 50 ohms microstrip line feeding used. This single band antenna is simulated on a Rogers RT5880 dielectric substrate have relative permittivity 2.2, loss tangent 0.0009, and height 1.6mm. The antenna is simulated by Electromagnetic simulation, computer software technology Microwave studio. The proposed single band antenna and simulated result on return loss, VSWR, surface current and 3D radiation pattern is presented. The simulated antenna shows the return loss −40.99dB at 60 GHz millimeter wave 5G wireless application presented.

Small form factor dual band (28/38 GHz) PIFA antenna for 5G applications

Abstract: This paper presents for the first time, the design of a dual band PIFA antenna for 5G applications on a low-cost substrate with smallest form factor and widest bandwidth in both bands (28 GHz and 38 GHz). The proposed dual band PIFA antenna consists of a shorted patch and a modified U-shaped slot in the patch. The antenna shows good matching at and around both center frequencies. The antenna shows clean radiation pattern and bandwidth of 3.34 GHz and 1.395 GHz and gain of 3.75 dBi and 5.06 dBi at 28 and 38 GHz respectively. This antenna has ultra-small form factor of 1.3 mm × 1.2 mm. Patch is shorted at one end with a metallic cylindrical via. A CPW line and a feeding via are used on the bottom side of the substrate to excite the PIFA antenna patterned on the top side of the substrate which also facilitate the measurements of the antenna at mm-wave frequencies. The antenna was designed on low cost Isola FR406 substrate.

A Wideband Dual-Polarized Antenna With Two Independently Controllable Resonant Modes and Its Array for Base-Station Applications

Abstract: A wideband dual-polarized antenna with two independently controllable resonant modes for 2G/3G/4G bands is proposed. Its radiator mainly consists of two crossed stepped-width loop dipoles loaded with two crossed straight dipoles. Two approaches are adopted to design the proposed antenna with large freedom. First, by replacing the traditional uniform-width loop dipole with a stepped-width one, the first resonant mode can be adjusted independently by controlling the width ratio of the loop. Second, a pair of crossed straight dipoles are embedded into the gap of the crossed loop dipoles, and the second resonant mode can be controlled independently by altering the length or position of the straight dipoles. Measurements show that the antenna achieves an impedance bandwidth of 54.5% with VSWR< 1.5 (1.68–2.94 GHz) and isolation of greater than 28.5 dB within the bandwidth. Also, an antenna array with ten elements is developed with electrical downtilt from 0° to 8° for practical base-station applications.

Flexible Folded-Patch Antenna With Serrated Edges for Metal-Mountable UHF RFID Tag

Abstract: A folded-patch tag antenna (30 mm x 30 mm x 3 mm or 0.0912λ x 0.0912λ x 0.009λ) is designed for mounting on metallic objects. It consists of a serrated patch radiator, ground patch, and loopshaped stub, which are made on a flexible inlay wrapping around soft foam. Digital serration is used for fine-tuning the resonant frequency. The proposed tag antenna is able to achieve a read range beyond 7 m on metal. It can also be read from at least 3.5 m when used on dielectrics with permittivity in the range from 1 to 12.

Compact Dual-Band Textile PIFA for 433-MHz/2.4-GHz ISM Bands

Abstract: A textile planar inverted-F antenna (PIFA) is proposed. By co-designing the PIFA antenna and the ground plane, a wide matching bandwidth is achieved around 433 MHz for a relatively small electrical size (0.202 × 0.115 × 0.01 λ 03). A slot within the PIFA patch enables the 2.4-GHz operating band. The measured bandwidths are 35 and 309 MHz in the lower and upper bands, respectively. The corresponding radiation efficiencies are 48% and 64%. The analysis of the effect of bending and the on-body characterization show the robust performance of the antenna.

A mm-Wave Patch Antenna with Broad Bandwidth and a Wide Angular Range

Abstract: A novel mm-wave microstrip-fed patch antenna with broad bandwidth and wide angular coverage suitable for integration in planar arrays is designed, analyzed, and verified by measurements. The antenna provides a bandwidth of 13.1% between 34.1 and 38.9 GHz, which is achieved by a slotted multiple resonances microstrip patch and a matching circuit in microstrip technology. The antenna is built on RO3003 substrate with top and ground layers, which is low cost compared with other techniques. For simple integration with microstrip and frontend circuits, the feeding happens at the top layer with a microstrip coupling gap feed. The wide half-power beamwidth (HPBW) is achieved by suitably designed parasitic patches for the first resonant mode. The second resonant mode has a wide HPBW by default. The HPBW is between 100° and 125° within the matched bandwidth, which is a very good value for a microstrip patch antenna radiating over a ground plane. The measured input impedance and radiation characteristic show very good agreement with simulation results.

Frequency Reconfigurable Multiband Handset Antenna Based on a Multichannel Transceiver

Abstract: The upcoming standards of wireless communications result in additional and more stringent requirements for antennas in mobile phones. In this paper, we present a frequency-reconfigurable antenna that could potentially be suited for future mobile devices. Frequency reconfigurability is achieved through a cluster of mutually coupled antenna elements that is excited with frequency-dependent weights using a multichannel transceiver. We report a mobile handset antenna cluster measuring 15 $\times $ 15 $\times $ 1.6 mm3 that covers the frequency bands of 1.7–2.7, 3.3–4.5, and 5.475–6.425 GHz with an antenna efficiency better than 90%. The operation of the antenna cluster is experimentally verified by feeding all the antenna elements with proper weights using tailor-made power splitters that represent a multichannel transceiver with adjustable amplitude and phase in each branch. The results obtained with the feed networks suggest the feasibility of the reconfigurability concept and pave way for codesign of the antenna and the transceiver.

Analysis of single band and dual band graphene based patch antenna for terahertz region

Abstract: A microstrip patch antenna is designed using a very thin layer of graphene as the radiating patch, which is fed by a microstrip transmission line. The graphene based patch is designed on a silicon substrate having a dielectric constant of 11.9, to radiate at a single frequency of 2.6 THz. Further, this antenna is made to resonate at dual frequencies of 2.48 THz and 3.35 THz, by changing the substrate height, which is reported for the first time. Various antenna parameters such as return loss, VSWR, gain, efficiency and bandwidth are also determined for the single and dual band operation. For the single band operation, a bandwidth of 145.4 GHz and an efficiency of 92% was achieved. For dual band operation, a maximum bandwidth of 140.5 GHz was obtained at 3.35 THz and an efficiency of 87.3% was obtained at the first resonant frequency of 2.48 THz. The absorption cross section of the antenna is also analysed for various substrate heights and has maximum peaks at the corresponding resonating frequencies. The simulation has been carried out by using a full wave electromagnetic simulator based on FDTD method.

A Compact Quasi-Isotropic Antenna Based on Folded Split-Ring Resonators

Abstract: In this letter, an electrically small quasi-isotropic antenna using folded split-ring resonators is investigated. The antenna is based on split-ring resonators (SRRs) to achieve a quasi-isotropic radiation pattern using the electric and magnetic dipole current of the SRR. Interdigital capacitors are used to make the size more compact, and magnetic coupling of a folded structure is applied to improve the radiation characteristics of the SRR antenna. The electrical size of the antenna has ka = 0.41 at 888 MHz and 1.8% of fractional bandwidth. The measured gain deviation $(\Delta)$ is 5.2 dB and the measured radiation efficiency is higher than 81% in the bandwidth.

Cavity-Backed Proximity-Coupled Reconfigurable Microstrip Antenna With Agile Polarizations and Steerable Beams

Abstract: A major challenge for a combined reconfigurable antenna is to realize both polarization switching and beam steering independently in a compact antenna structure. A cavity-backed proximity-coupled reconfigurable microstrip antenna proposed in this communication provides an efficient solution. Beam lead p-i-n diodes DSM8100–000 are employed as switching elements to achieve reconfiguration. Three different linear polarizations (0°, 45°, and 90°) are realized by switching the diodes on a proximity-coupled feed network. For each polarization state, the main beam can be steered to three directions by using a reconfigurable parasitic-element network. The parasitic-element network is printed on the same plane of the radiating patch, thereby making the antenna compact. This antenna has nine different working modes, and for all the working modes, the reflection coefficients are below −10 dB with the measured realized gains ranging from 7.2 to 8.1 dBi.

A Planar Integrated Folded Reflectarray Antenna With Circular Polarization

Abstract: This communication presents the complete design of a circularly polarized (CP) folded reflectarray (FRA) antenna with an integrated planar structure for the first time in the open literature. To achieve circularly polarized, a printed meander-line polarizer is designed and integrated with the linearly polarized (LP) FRA. To achieve a low-profile planar structure, an integrated $2 \times 2$ planar array is designed as the feed source instead of a horn. Thus, the whole antenna, including the feed source, LPFRA, and meander-line polarizer, can be fully integrated and fabricated using low-cost printed circuit board technology. To validate the concept, a right-handed CPFRA operating in C-band is designed, fabricated, and measured. The broadside axial ratio (AR) of the proposed CPFRA is lower than 1 dB over a bandwidth from 5.22 to 5.46 GHz. In addition, the maximum gain of 22.8 dBic is obtained at 5.38 GHz with the antenna efficiency of 27%. The antenna is promising for applications in satellite communication due to advantages of low profile, easy fabrication, low cost, and high gain.

A Low-Profile Wide-Bandwidth Planar Inverted-F Antenna Under Dual Resonances: Principle and Design Approach

Abstract: A low-profile planar inverted-F antenna (PIFA) under the operation of TM0,1/2 and TM2,1/2 modes in a single patch resonator for bandwidth enhancement is proposed. Initially, our study demonstrates that all of the even-order modes can effectively be suppressed by employing a rectangular PIFA instead of the conventional microstrip patch antenna. Then, a pair of shorting pins is appropriately loaded underneath the side-shorted radiating patch to investigate the variation of their odd-mode resonant frequencies. The results indicate that the resonant frequency of TM0,1/2 mode ( $f_{0,1/2}$ ) is dramatically increased up while almost maintaining that of TM2,1/2 mode ( $f_{2,1/2}$ ). After that, the width of the radiating patch is progressively enlarged in order to move the $f_{2,1/2}$ more closely to the $f_{0,1/2}$ . By using this approach, the dual radiative resonant modes can be reallocated in proximity to each other. Additionally, a narrow slot is etched out on the radiating patch so as to counteract the equivalent inductance caused by the shorting pins and probe. As such, a wide-bandwidth with stable radiation pattern is achieved for the PIFA under the operation of these dual-resonant modes. After the extensive analysis is executed, the proposed antenna is fabricated and tested. Simulated and measured results are found in good agreement with each other, demonstrating that its impedance bandwidth is tremendously widened to about 15.3% with appearance of two in-band attenuation poles. In particular, a low-profile property with the height of 0.036 free-space wavelength is achieved.

Folded Strip/Slot Antenna With Extended Bandwidth for WLAN Application

Abstract: A compact and novel printed antenna for 2.4-GHz WLAN/Zigbee/Bluetooth applications is proposed in this letter. To extend the bandwidth, a strip mode and a slot mode are combined together, which generate a dual-mode response inside the radiating band. To miniaturize the overall size, the structure is folded in order to fully utilize the available antenna space. The antenna is fabricated on a 1-mm FR4 board and excited by an SMA connector using a short microstrip line. It achieves a –10-dB bandwidth of 5.09% with a compact size of 0.073 λ 0 × 0.052 λ 0 × 0.008 λ 0 (9.2 × 6.5 × 1 mm3) and an in-band radiation efficiency above 73%. It is small and low-profile, which can be fabricated at a low cost using the standard printed circuit board (PCB) process. It shows good radiation performance and therefore is suitable for applications in Internet of Things and smart home devices.

A Q-Slot Monopole for UWB Body-Centric Wireless Communications

Abstract: This paper presents a novel and simple ultrawideband printed rectangular monopole antenna for body-centric wireless communications. The design is based on etching a Q-slot on a rectangular radiator and is optimized to produce the largest bandwidth in free space and close to the human body. We analyze the design of the proposed antenna and assess its performance in terms of bandwidth, gain, efficiency, and radiation patterns. We also characterize the antenna in the time-domain by calculating its fidelity factor. Our results show that the Q-slot antenna maintains its bandwidth when placed in close contact with the human body, or in contact with breast-mimicking tissue phantoms. The very good agreement between the calculated and measured antenna performances in free space and on body suggests that the antenna is immune to variations in the human tissue and is also robust to fabrication tolerances.

Dual-band 8-element MIMO antenna with short neutral line for 5G mobile handset

Abstract: A design of compact dual band 8-element MIMO antenna using folded monopole structures is proposed The MIMO antenna consists of 8 folded monopole antenna elements, each two of them are symmetrically placed on the orthogonal frame corners of the substrate, and closely located to each other with no clearance on the ground The folded monopole arms are used as radiation elements to resonate at two different bands of 34–36 GHz and 455–475 GHz Each closely placed two antenna elements are connected by a 3 mm short neutral line which can be used to reduce the mutual coupling at both bands By optimizing the antenna structure and neutral line, dual band decoupling can be achieved The isolation and efficiency of the MIMO antenna is improved and the calculated ergodic channel capacities with a 20 dB SNR at both bands reach to 412 bps/Hz and 403 bps/Hz, respectively, very close to the ideal case of 8×8 MIMO system

Conical Conformal Shaped-Beam Substrate-Integrated Waveguide Slot Array Antenna With Conical-to-Cylindrical Transition

Abstract: The analysis and design of a millimeter-wave conical conformal shaped-beam substrate-integrated waveguide (SIW) array antenna is demonstrated in this paper. After investigating the influence of the conical surface on the propagation characteristics of a conformal SIW, a modification for the width of a conical conformal SIW is proposed to obtain the same propagation characteristic along the longitudinal direction. This feature is indispensable to employ the classic equivalent circuit of a planar slot array antenna in the design of a conical conformal antenna. In this case, the design process of the conformal antenna can be simplified. An efficient and accurate model method of the conical conformal SIW antenna is presented as well. Then, a design process of the conical conformal SIW slot array antenna is introduced. Furthermore, to implement the transition between a conical surface and a cylindrical surface, a flexible SIWtransition is designed with a good impedance matching. Finally, two low sidelobe level (SLL) SIW conical conformal antennas with and without the flexible transitions are designed. Both of them have −28 dB SLLs in H-plane at the center frequency of 35 GHz.

Koch boundary on the square patch microstrip antenna for ultra wideband applications

Abstract: In this paper a novel compact microstrip feed square patch antenna with right angled isosceles Koch fractal geometry on its edges is designed for ultra wideband applications. The radiating patch is modified in several steps to achieve a multiband circularly polarized antenna. The fractal antenna is simulated using CST Microwave Studio Simulator. Antenna’s performance is then compared with equilateral Koch, Minkowski and Sierpinski fractal geometries. The suggested antenna is assembled on FR4-epoxy (er = 4.4) substrate with dimensions 60 × 55 × 1.59 mm3. The developed antenna efficiently operates at 4.3 GHz, 5.0 GHz, 6.1 GHz, 7.4 GHz, 8.9 GHz and 9.2 GHz. Circular polarizations are achieved near four resonant frequencies, which are realized by adding a circle in the middle of the patch. The presented antenna has a good gain, bandwidth, VSWR and axial ratio bandwidth. In this paper, an approach for multiband antennas is proposed. The novelty of the paper lies in the fact that a right angled triangular Koch curve is formed on the edges of the square patch.

Inverted-S Antenna With Wideband Circular Polarization and Wide Axial Ratio Beamwidth

Abstract: A novel broadband circularly polarized (CP) antenna with wide axial ratio (AR) beamwidth is proposed. It is composed of two curved arms shaped like an inverted “S.” The mechanisms of wideband CP operation and wide AR beamwidth are explained. To validate the concept, a prototype at C-band is manufactured and measured. Experimental results confirm that the antenna achieves an impedance bandwidth of 63% and a CP bandwidth of 42%. Furthermore, maximum AR beamwidth of 140° is achieved and wide AR beamwidth can be maintained in a frequency bandwidth of 35% in nearly all elevation planes. In addition, the antenna has the advantage of being easily extended to arrays. A four-element array using the proposed antenna is investigated through both simulations and experiments, and achieves 60% CP bandwidth and wide AR beamwidth. The proposed inverted-S antenna can realize wide CP bandwidth and wide AR beamwidth, and can easily form wideband CP arrays.

Low-Profile and Wide-Beamwidth Dual-Polarized Distributed Microstrip Antenna

Abstract: A low-profile and wide-beamwidth dual-polarized distributed microstrip antenna is presented in this paper. Four isolated micro patches are proposed as the radiation components and are excited by a compact differential-fed network. The micro patches in two diagonals determine the operating frequency bands of the two polarizations, respectively. By increasing the distances between the micro patches, the beamwidth in E plane can be broadened. Shorting poles between the patches and the ground plane are used to achieve good impedance matching. Compact dual-polarized differential-fed networks are also studied and compared with achieve the best antenna performance. To validate the proposed method, a wide-beamwith dual-polarized distributed microstrip antenna, whose dual polarizations operate at 2 and 2.2 GHz, respectively, is manufactured and measured. The external dimensions of the antenna is 70mm $\times 10$ mm ( $0.49\lambda \times 0.07\lambda$ ). The experimental results agree well with the simulated ones. The 3dB beamwidths in E planes reach 116° and 115°, and the gains are 5.15 and 5.5 dB for two polarizations, respectively. Meanwhile, the cross polarizations are less than −26.2 and −27.8 dB. In addition, the impedance bandwidths of 9.2% and 9.9% for VSWR $\leq 2$ are achieved, and the port isolation is greater than 25.4 dB in the bands.

Reconfigurable Loop Antenna With Two Parasitic Grounded Strips for WWAN/LTE Unbroken-Metal-Rimmed Smartphones

Abstract: A reconfigurable loop antenna with two parasitic grounded strips for modern smartphone devices is presented in this paper. The most essential merit of this proposed reconfigurable antenna is that it can keep the intactness of the outer metal rim. In addition, it can generate multiantenna modes. The outer metal rim generates three loop modes and the inner parasite grounded strips can provide two monopole modes. By merging these two types of antenna modes, it can offer two wide bandwidths to cover GSM850/900, DCS/PCS/UMTS2100, and LTE2300/2500 operations with a compact antenna size of 945 mm2. The detailed operating principles and design considerations of this proposed reconfigurable antenna are described. In order to validate this proposed antenna, it was fabricated and tested. The measured antenna efficiencies and gains are satisfied with the requirements for the modern communication devices.