Showing papers on "Dipole antenna published in 2015"
Patent•
AT&T1
TL;DR: In this paper, the authors describe a system that receives, by a feed point of a dielectric antenna, electromagnetic waves from a core coupled to the feed point without an electrical return path, and radiates a wireless signal responsive to the electromagnetic waves being received at the aperture.
Abstract: Aspects of the subject disclosure may include, for example, receiving, by a feed point of a dielectric antenna, electromagnetic waves from a dielectric core coupled to the feed point without an electrical return path, where at least a portion of the dielectric antenna comprises a conductive surface, directing, by the feed point, the electromagnetic waves to a proximal portion of the dielectric antenna, and radiating, via an aperture of the dielectric antenna, a wireless signal responsive to the electromagnetic waves being received at the aperture. Other embodiments are disclosed.
330 citations
01 Jan 2015
TL;DR: In this article, the authors focused on circularly polarized antennas and provided key definitions and governing equations of circular polarization, and extended the concept to the magnetic source counterparts and Huygens sources.
Abstract: This chapter is focused on circularly polarized antennas. Key definitions and governing equations of circular polarization are given. Infinitesimal dipole sources are considered to establish circularly polarized radiation. First, radiation patterns of cross dipoles are mathematically reviewed, from which the condition of circularly polarized waves is concluded. Later, the idea is extended to four displaced sequentially rotated dipole antennas, resulting in circularly polarized waves within a wide angular range in space. The extension of the concept to the magnetic source counterparts and Huygens sources is briefly discussed. Other than point sources, also known as one-dimensional current sources, sources of circularly polarized radiation are further investigated for two-dimensional cases, such as microstrip patch antennas, and threedimensional structures, such as volumetric current sources existing in dielectric resonator antennas. For these cases, the creation of circularly polarized radiation using single-feed and dual-feed, perturbed structures and sequentially rotated method is described. As a design example, numerical andmeasurement results of circularly polarized square patch ring antennas are extensively discussed and presented in this chapter. The square-ring microstrip antenna is selected as it closely approximates the sequentially rotated currents, and also it has not been widely studied in the literature.
327 citations
TL;DR: In this paper, a bandwidth-enhanced, compact, monopole antenna with modified ground plane for modern automotive ultra wideband (UWB) applications is presented, where the ground plane of the fundamental radiator is curved and defected to improve the VSWR bandwidth.
Abstract: This communication presents a bandwidth-enhanced, compact, monopole antenna with modified ground plane for modern automotive ultra wide-band (UWB) applications The proposed antenna has hybrid geometry and is constructed using half circular ring and half square ring The ground plane of the fundamental radiator is curved and defected to improve the VSWR bandwidth An extended ground stub is added to further enhance the bandwidth to suit the modern automotive requirements The designed antenna covers 31–109 GHz frequency spectrum with ${\mathrm {VSWR}} \leq {2}$ This antenna can be conveniently placed inside the shark fin housing or it can be printed along with the existing print circuit board (PCB) electronics nullifying the need for dedicated location for in-car communications Furthermore, a simple two-port multiple input multiple output (MIMO) antenna is constructed and its diversity performance is estimated The prototype is fabricated and tested for impedance and radiation characteristics
225 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, a multiple-input-multiple-output (MIMO) band-notched antenna with a compact size of only $22 \times 36\;\mathrm{mm}^2 $ is proposed for portable ultrawideband (UWB) applications.
Abstract: A multiple-input-multiple-output (MIMO) band-notched antenna with a compact size of only $22 \times 36\;\mathrm{mm}^2 $ is proposed for portable ultrawideband (UWB) applications. The antenna consists of two square monopole-antenna elements, a T-shaped ground stub, a vertical slot cut on the T-shaped ground stub to reduce mutual coupling, and two strips on the ground plane to create a notched frequency band. Simulation and measurement are used to study the antenna performance in terms of impedance matching, isolation between the two input ports, radiation pattern, efficiency, peak gain, and envelope correlation coefficient. Results show that the antenna can operate from 3.1 to more than 11 GHz with a notched band in 5.15–5.85 GHz. In the center notched frequency, the efficiency drops to 7%, indicating a good interference suppression performance. The mutual coupling is less than $- 15\;\mathrm{dB}$ and the envelope correlation coefficient is less than 0.1. The performances of the MIMO antenna when installed on a PCB with a standard size, with an USB connector and device housing, are also studied. Results show that the proposed MIMO antenna is a good candidate for portable UWB applications.
202 citations
TL;DR: In this article, a compact circularly polarized (CP) co-designed filtering antenna is reported, which is based on a patch radiator seamlessly integrated with a bandpass filter composed of coupled stripline open-loop resonators, which are designed together as a system.
Abstract: A compact circularly polarized (CP) co-designed filtering antenna is reported. The device is based on a patch radiator seamlessly integrated with a bandpass filter composed of coupled stripline open-loop resonators, which are designed together as a system. In the proposed design, the patch functions simultaneously as the radiator and the last stage resonator of the filter, resulting in a low-profile integrated radiating and filtering module with a small overall form factor of $\mathbf{0.53{\lambda _0} \times 0.53{\lambda _0} \times 0.07{\lambda _0}}$ . It is shown that the filtering circuit not only ensures frequency selectivity but also provides impedance matching functionality, which serves to broaden both the impedance and axial ratio bandwidths. The designed filtering antenna was fabricated and measured, experimentally achieving an $\mathbf{{S_{11}} , an axial ratio of less than 3 dB and a gain higher than 5.2 dBi over a bandwidth from 3.77 to 4.26 GHz, i.e., around 12.2%, which makes it an excellent candidate for integration into a variety of wireless systems. A linearly polarized version of the integrated filtering antenna was also demonstrated. In addition, further full-wave simulations and experiments were carried out to verify that the designed CP filtering antenna maintains its properties even when mounted on different positions of the human body with various body gestures. The stable impedance and radiation properties also make it a suitable candidate as a wearable antenna for off-body wireless communications.
188 citations
TL;DR: In this article, a compact octagonal shaped fractal ultrawideband multiple-input-multiple-output (MIMO) antenna is presented, and its characteristics are investigated in order to achieve the desired miniaturization and wideband phenomena.
Abstract: In this letter, a compact octagonal shaped fractal ultrawideband multiple-input–multiple-output antenna is presented, and its characteristics are investigated In order to achieve the desired miniaturization and wideband phenomena, self-similar and space filling properties of Koch fractal geometry are used in the antenna design These fractal monopoles are placed orthogonal to each other for good isolation Moreover, grounded stubs are used in the geometry to provide further improvement in the isolation The band rejection phenomenon in wireless local area network band is achieved by etching a C-shaped slot from the monopole of the antenna The proposed antenna has compact dimensions of $45~\hbox{mm} \times 45~\hbox{mm}$ and exhibits quasi-omnidirectional radiation pattern In addition, it shows an impedance bandwidth ( ${{\rm S}_{11}}\! ) from 2 to 106 GHz with isolation better than 17 dB over the entire ultra-wideband range Diversity performance is also evaluated in terms of envelope correlation coefficient and capacity loss The measured results show good agreement with the simulated ones
188 citations
TL;DR: In this article, a compact multiple-input-multiple-output (MIMO) antenna with band-notched function is presented for ultrawideband (UWB) applications.
Abstract: A compact multiple-input–multiple-output (MIMO) antenna is presented for ultrawideband (UWB) applications with band-notched function. The proposed antenna is composed of two offset microstrip-fed antenna elements with UWB performance. To achieve high isolation and polarization diversity, the antenna elements are placed perpendicular to each other. A parasitic T-shaped strip between the radiating elements is employed as a decoupling structure to further suppress the mutual coupling. In addition, the notched band at 5.5 GHz is realized by etching a pair of L-shaped slits on the ground. The antenna prototype with a compact size of $38.5 \times38.5~\hbox{mm}^{2}$ has been fabricated and measured. Experimental results show that the antenna has an impedance bandwidth of 3.08-11.8 GHz with reflection coefficient less than $-10~\hbox{dB}$ , except the rejection band of 5.03-5.97 GHz. Besides, port isolation, envelope correlation coefficient and radiation characteristics are also investigated. The results indicate that the MIMO antenna is suitable for band-notched UWB applications.
174 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: In this paper, a printable radio frequency identification (RFID) antenna was demonstrated by low temperature processing of graphene ink, which was achieved by rolling compression of binder-free graphene laminate.
Abstract: In this paper, we demonstrate realization of printable radio frequency identification (RFID) antenna by low temperature processing of graphene ink. The required ultra-low resistance is achieved by rolling compression of binder-free graphene laminate. With compression, the conductivity of graphene laminate is increased by more than 50 times compared to that of as-deposited one. Graphene laminate with conductivity of 4.3 × 104 S/m and sheet resistance of 3.8 Ω/sq (with thickness of 6 μm) is presented. Moreover, the formation of graphene laminate from graphene ink reported here is simple and can be carried out in low temperature (100 °C), significantly reducing the fabrication costs. A dipole antenna based on the highly conductive graphene laminate is further patterned and printed on a normal paper to investigate its RF properties. The performance of the graphene laminate antenna is experimentally measured. The measurement results reveal that graphene laminate antenna can provide practically acceptable retur...
TL;DR: In this article, a multimode filtering antenna, which is realized by integrating a multi-modal resonator and an antenna, has been applied to the design of dual-polarized antenna arrays for achieving a compact size and high performance in terms of broad bandwidth, high-frequency selectivity and out-of-band rejection.
Abstract: A novel design concept of multimode filtering antenna, which is realized by integrating a multimode resonator and an antenna, has been applied to the design of dual-polarized antenna arrays for achieving a compact size and high performance in terms of broad bandwidth, high-frequency selectivity and out-of-band rejection. To verify the concept, a $2 \times 2$ array at C-band is designed and fabricated. The stub-loaded resonator (SLR) is employed as the feed of the antenna. The resonant characteristics of SLR and patch as well as the coupling between them are presented. The method of designing the integrated resonator-patch module is explained. This integrated design not only removes the need for separated filters and traditional ${50}{\text - }{\Omega }$ interfaces but also improves the frequency response of the module. A comparison with the traditional patch array has been made, showing that the proposed design has a more compact size, wider bandwidth, better frequency selectivity, and out-of-band rejection. Such low-profile light weight broadband dual-polarized arrays are useful for space-borne synthetic aperture radar (SAR) and wireless communication applications. The simulated and measured results agree well, demonstrating a good performance in terms of impedance bandwidth, frequency selectivity, isolation, radiation pattern, and antenna gain.
TL;DR: In this paper, a broadband dual-polarized antenna array with five elements for the band is developed for base station application, and the measured results show achievement of impedance bandwidth of 45% for both ports, port-to-port isolation $>$ 25 dB, a stable radiation pattern with 3-dB beamwidth $68^{\circ}\pm 2^{circ}$ at H-plane and V-plane.
Abstract: A broadband $\pm 45^{\circ}$ dual-polarized base station antenna is proposed for 2G/3G/LTE bands. The proposed antenna has Y-shaped feeding lines to impart a wide impedance bandwidth to it, and a rectangular box-shaped reflector to enhance its stability in radiation patterns over the operating frequencies. A prototype of the proposed antenna is designed, fabricated, and tested. The measured results show achievement of impedance bandwidth of 45% for $\hbox {SWR} at both ports, port-to-port isolation $>$ 25 dB , a stable radiation pattern with 3-dB beamwidth $68^{\circ}\pm 2^{\circ}$ at H-plane and V-plane, and a stable antenna gain of 8.2 $\pm$ 0.6 dBi from 1.7 to 2.7 GHz. A broadband dual-polarized antenna array with five elements for the band is developed for base station application. Measurements show achievement of array gain of 14.8 $\pm$ 1.4 dBi, 3-dB beamwidth $66.56^{\circ}\pm 2.22^{\circ}$ at H-plane at port 1 and $64.85^{\circ}\pm 4.96^{\circ}$ at port 2 with $\hbox {SWR} over the operating frequency band. Simulation results have a good agreement with measurement ones.
TL;DR: In this article, a dual-band wearable fractal-based monopole patch antenna integrated with an electromagnetic band-gap (EBG) structure is presented for the GSM-1800 MHz and ISM-2.45 GHz bands.
Abstract: This letter presents the design of a dual-band wearable fractal-based monopole patch antenna integrated with an electromagnetic band-gap (EBG) structure. The prototype covers the GSM-1800 MHz and ISM-2.45 GHz bands. The EBG structure reduces the radiation into the human body over 15 dB. It also reduces the effect of frequency detuning due to the human body. The performance of the antenna under bending, crumpling, and on-body conditions has been studied and presented. Specific absorption rate (SAR) assessment has also been performed to validate the antenna for its usefulness in wearable applications.
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.
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.
TL;DR: In this article, a crossed dipole that is loaded with a magneto-electric dipole to produce the wideband and wide-beam circularly polarized radiation characteristics is proposed.
Abstract: A crossed dipole that is loaded with a magneto-electric dipole to produce the wideband and wide-beam circularly polarized radiation characteristics is proposed. The crossed dipole is incorporated with double-printed vacant-quarter rings to feed the antenna. The antenna is backed by a metallic cavity to provide a unidirectional radiation pattern with a wide axial-ratio (AR) beamwidth and a high front-to-back ratio. Experimental results showed that the prototype with an overall size of $120\times 120\times30.5~\hbox{mm}^3$ has a $\vert { S}_{11}\vert bandwidth of 1.274–2.360 GHz and a 3-dB AR bandwidth of 1.39–1.82 GHz. The antenna showed a right-hand circular polarization (CP) radiation with a very wide 3-dB AR beamwidth ( $>165^{\circ}$ ) and a high radiation efficiency ( $ > 94\%$ ) within the operational bandwidth.
TL;DR: A wideband high-gain high-efficiency hybrid integrated plate array antenna for inter-satellite links is presented in this paper, which consists of microstrip patches, substrate integrated waveguide (SIW) and waveguide power dividers.
Abstract: A wideband high-gain high-efficiency hybrid integrated plate array antenna for inter-satellite links is presented in this paper This antenna consists of microstrip patches, substrate integrated waveguide (SIW) and waveguide power dividers A novel feeding structure is proposed to excite the microstrip sub-array with a wideband characteristic The radiation efficiency of SIW arrays with different sizes is compared by experiment The hybrid SIW-waveguide feeding topology is optimized to realize high efficiency, low cost and compact configuration at the same time The array antenna is fabricated through standard multi-layer PCB process and milling technology Measured results demonstrate about 146% of reflection coefficient bandwidth ( $\vert {\rm S}_{11}\vert dB) in the frequency band of 57–66 GHz The gain fluctuates less than 3 dB within the same band The 1 dB gain bandwidth is 81% within the frequency band of 59–64 GHz The maximum gain is 392 dBi at 59 GHz with the efficiency of 41%
TL;DR: In this paper, a dual-band textile antenna for multiple-input-multiple-output (MIMO) applications, based on substrate-integrated waveguide (SIW) technology, is designed.
Abstract: A dual-band textile antenna for multiple-input–multiple-output (MIMO) applications, based on substrate-integrated waveguide (SIW) technology, is designed. The fundamental SIW cavity mode is designed to resonate at 2.4 GHz. Meanwhile, the second and third modes are modified and combined by careful placement of a via within the cavity to enable wideband coverage in the 5-GHz WLAN band. The simple antenna topology can be fabricated fully using textiles in a planar form, ensuring reliability and comfort. Numerical and experimental results indicate satisfactory antenna performance when worn on body in terms of impedance bandwidth, radiation efficiency, and specific absorption ratio (SAR). In order to validate its potential for MIMO applications, two elements of the proposed SIW antenna are arranged in six configurations to study the performance in terms of mutual coupling and envelope correlation. It is observed that the placement of the shorted edges of the two elements adjacent to each other produces the lowest mutual coupling and consequently the best envelope correlation.
TL;DR: A frequency-reconfigurable bow-tie antenna for Bluetooth, WiMAX, and WLAN applications is proposed, which shows that the proposed antenna can be tuned to operate in either 2.2-2.53, 2.97-3.71, or 4.51-6 GHz band with similar radiation patterns.
Abstract: A frequency-reconfigurable bow-tie antenna for Bluetooth, WiMAX, and WLAN applications is proposed. The bow-tie radiator is printed on two sides of the substrate and is fed by a microstripline continued by a pair of parallel strips. By embedding p-i-n diodes over the bow-tie arms, the effective electrical length of the antenna can be changed, leading to an electrically tunable operating band. The simple biasing circuit used in this design eliminates the need for extra bias lines, and thus avoids distortion of the radiation patterns. Measured results are in good agreement with simulations, which shows that the proposed antenna can be tuned to operate in either 2.2–2.53, 2.97–3.71, or 4.51–6 GHz band with similar radiation patterns.
TL;DR: In this article, a wearable dual-band magneto-electric dipole antenna is proposed, where two U-shaped slots are introduced on a dipole and the resulting electric and magnetic resonances are combined with the aim to produce a dual band with wideband characteristics.
Abstract: A wearable dual-band magneto-electric dipole antenna is proposed. Two U-shaped slots are introduced on a dipole and the resulting electric and magnetic resonances are combined with the aim to produce a dual band with wideband characteristics. The antenna is fabricated fully using textiles, except for the feeding connector. Simulations and measurements confirm the wide bandwidth and a low backward radiation in both the lower and the upper band. The antenna is robust and not very sensitive to bending when worn by the user. The specific absorption rate is studied numerically and proven to be well below the European limit of 2 W/kg.
TL;DR: In this paper, a low-cost inkjet-printed multiband antenna for integration into flexible and conformal mobile devices is presented, which covers four wide frequency bands with measured impedance bandwidths of 54.4, 14, 23.5% and 17.2%, centered at 1.2, 2.6 and 3.4 GHz, respectively.
Abstract: A low-cost inkjet-printed multiband antenna envisioned for integration into flexible and conformal mobile devices is presented. The antenna structure contains a novel triangular iterative design with coplanar waveguide (CPW) feed, printed on a Kapton polyimide-based flexible substrate with dimensions of $ 70\times 70\times 0.11~\hbox{mm}^{\bf 3}$ . The antenna covers four wide frequency bands with measured impedance bandwidths of 54.4%, 14%, 23.5% and 17.2%, centered at 1.2, 2.0, 2.6 and 3.4 GHz, respectively, thus, enabling it to cover GSM 900, GPS, UMTS, WLAN, ISM, Bluetooth, LTE 2300/2500 and WiMAX standards. The antenna has omnidirectional radiation pattern with a maximum gain of 2.1 dBi. To characterize the flexibility of the antenna, the fabricated prototype is tested in convex and concave bent configurations for radii of 78 mm and 59 mm. The overall performance remains unaffected, except a minor shift of 20 MHz and 60 MHz in S11, for concave bending at both radii. The compact, lightweight and conformal design as well as multiband performance in bent configurations, proves the suitability of the antenna for future electronic devices.
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.
TL;DR: In this paper, a compact ultrawideband (UWB) multiple-input multiple-output (MIMO) antenna, with high isolation, is proposed for portable UWB MIMO systems.
Abstract: A compact ultrawideband (UWB) multiple-input multiple-output (MIMO) antenna, with high isolation, is proposed for portable UWB MIMO systems. Two coplanar stripline-fed staircase-shaped radiating elements are connected back-to-back. The prototype is designed on a substrate of dielectric constant 4.4 with an overall dimension of $25\,\mathrm{mm}\times 30\,\mathrm{mm}\times 1.6\,\mathrm{mm}$ . This antenna configuration with an isolating metal strip placed in between the two radiating elements ensures high isolation in the entire UWB band. The proposed antenna exhibits a good 2:1 VSWR impedance bandwidth covering the entire UWB band ( $3.1{-}10.6\,\mathrm{GHz}$ ) with a high isolation better than 20 dB, peak gain of 5.2 dBi, peak efficiency of 90%, and guaranteed value of envelope correlation coefficient (ECC) ${\leq}0.1641$ .
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.
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 dual-band three-pole Chebyshev filtering patch antenna with orthogonal polarizations in the two bands is developed for 2.4/5.8 GHz ISM-band applications.
Abstract: A compact dual-band three-pole Chebyshev filtering patch antenna with orthogonal polarizations in the two bands is developed for 2.4/5.8-GHz ISM-band applications. Step impedance resonators and aperture coupled feed techniques are integrated together to fulfill the goal. The synthesis procedure is discussed using formulation and design curves. The advantages of the proposed design, including harmonic suppression and controllable bandwidth, are verified by experiments. According to the summary table, this dual-band filtering antenna, realized in planar form, shows either a more compact size or improved radiation characteristics when compared with those reported in the open literature.
TL;DR: In this paper, a polarization reconfigurable wideband circularly polarized (CP) antenna is proposed, which consists of four radiating arms connected to a reconfigured feeding network, and the antenna gain is stable across the operating bandwidth with the peak gain of 4.8dBic.
Abstract: This communication introduces a polarization reconfigurable wideband circularly polarized (CP) antenna, which consists of four radiating arms connected to a reconfigurable feeding network. The four radiating arms excited by the feeding network are able to generate wideband CP waves with bidirectional radiation patterns in free space. In order to increase the gain and obtain a broadside radiation pattern, the proposed antenna is placed above a metallic reflector with the distance of quarter wavelength at the center frequency. In addition, polarization reconfigurability is realized by utilizing PIN diodes in the feeding transmission lines such that left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) modes can be selectively excited by controlling the on / off states of the PIN diodes. The proposed antenna exhibits a wide impedance bandwidth of 80% and an overlapped axial ratio (AR) bandwidth of 23.5% for both modes. The antenna gain is stable across the operating bandwidth with the peak gain of 4.8 dBic. The antenna has a wide AR beamwidth of 90°. The presented work is suitable for GPS, CNSS, or RFID applications.
TL;DR: In this article, a structure of a small ultra-wideband (UWB) monopole antenna, its design optimization procedure as well as experimental validation are presented, where antenna compactness is achieved by means of a meander line for current path enlargement and two parameterized slits providing additional degrees of freedom that help to ensure good impedance matching.
Abstract: In this letter, a structure of a small ultra-wideband (UWB) monopole antenna, its design optimization procedure as well as experimental validation are presented. According to our approach, antenna compactness is achieved by means of a meander line for current path enlargement as well as the two parameterized slits providing additional degrees of freedom that help to ensure good impedance matching. For the sake of reliability, the antenna design process (simultaneous adjustment of multiple geometry parameters) is carried out using high-fidelity EM analyses. Surrogate-based optimization involving an auxiliary coarse-discretization EM model it utilized to accomplish the design in practical timeframe. Penalty function approach allows us to reduce the antenna footprint (to only $15.8 \times 22~\hbox{mm}^2$ ) while maintaining acceptable reflection in the UWB frequency range. Experimental validation of the design is also provided.
TL;DR: In this paper, a broadband monopole antenna with circular polarization (CP) is designed and fabricated, which consists of a C-shaped monopole, an open-loop on the backside of the monopole and a modified ground plane.
Abstract: A novel broadband monopole antenna with circular polarization (CP) is designed and fabricated. It consists of a C-shaped monopole, an open-loop on the backside of the monopole and a modified ground plane. By placing a rectangular open-loop coplanar with the ground plane and connecting a rectangular vertical stub to the ground plane, wide impedance bandwidth is achieved, and axial-ratio (AR) bandwidth of the antenna could be improved simultaneously. The measured results exhibit a 65.2% (4.14 GHz, 4.28–8.42 GHz) CP bandwidth, and the 10-dB impedance bandwidth is 87.7% (6.66 GHz, 4.26–10.92 GHz). Finally, by placing a reflector underneath the antenna with its structural dimensions unchanged, one can obtain unidirectional radiation patterns with greatly improved gains. The advantages of the proposed antenna are the simple structure, a compact size, and a broad 3-dB AR bandwidth.