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A compact size, coplanar waveguide (CPW) fed two‐antenna multiple input multiple output (MIMO) with high isolation and excellent impedance matching operating in n77/n78/n79 5G NR sub‐6 GHz/Wi‐Fi‐5/V2X/DSRC/Wi‐Fi‐6/INSAT‐C is proposed for future wireless applications. Each antenna element is a CPW‐fed antenna type composed of an "inverted‐A," "y‐shaped," and "small extended stub" structures. The two‐antennas are deployed in the same orientation at an edge‐to‐edge distance of 0.06λ (λ represents free‐space wavelength at 3.70 GHz) on a shared rectangular substrate having designed footprint of 0.57λ × 0.39λ. To attain high isolation of greater than 20 dB in the desired bands of interest, a novel comb‐shaped isolating structure is deployed between the two antenna elements. From the measured results, the proposed MIMO antenna has exhibited wide 10‐dB impedance bandwidth of 88.57% (3.00‐7.70 GHz), good gain above 3 dBi and efficiency larger than 78% throughout the desired operating bands. Moreover, the MIMO diversity performance metrics including envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), total active reflection coefficient (TARC), channel capacity and channel capacity loss (CCL) are also achieved. [ABSTRACT FROM AUTHOR]

The authors propose an innovative double‐Xi‐shaped Chinese character artistic antenna backed by a high‐order‐mode cavity for 5G millimetre‐wave (mm‐wave) applications. The initial double‐Xi‐shaped microstrip antenna element is designed by using characteristic mode theory, and stable gain can be obtained across the whole 5G mm‐wave frequency band. By employing a slotted cavity with TE230 high‐order‐mode to excite 2×2 antenna subarray, a high gain of 13.2 ± 0.8 dBi and a high isolation better than 45 dB without additional feeding networks can be simultaneously achieved. To further improve the gain for reliable transmission, a 4×4 dual linearly polarised (LP) antenna array is also designed and fabricated. Measured results show that a wide frequency bandwidth of 11.45% (24.7–27.7 GHz) with a peak gain of 19.2 dBi and a high isolation of 33 dB is realised for the dual LP antenna array. The proposed method provides a simple and efficient prediction‐theory way to design artistic antenna for the first time, which solves the problem of designing specific‐shaped antenna without theoretical support. [ABSTRACT FROM AUTHOR]

A low-profile differentially fed dual-polarized antenna with high gain and isolation is proposed for fifth-generation (5G) microcell communications. By introducing two pairs of symmetrical meandering conductors to connect both ends of the radiating cross slots, a compact-size antenna with wide bandwidth can be achieved. By further adopting an artificial magnetic conductor-backed (AMC) reflector that is arranged below the radiating patches with a distance of 6 mm, the antenna profile can be reduced from $0.25\lambda _{c}$ to $0.13\lambda _{c}$ (where $\lambda _{c}$ is the free-space wavelength at the center frequency), while both the gain and frequency bandwidth are also enhanced. Furthermore, owing to the orthogonal differentially fed structure, the antenna element displays a high port isolation of 37 dB. Finally, by meticulously designing the feeding network, much narrower beamwidth can be yielded, and hence, the unidirectional gain is further improved. The measured results show that a lower-frequency bandwidth of 13.5% (3.26–3.73 GHz) with a gain of 15.7 ± 0.1 dBi and upper-frequency bandwidth of 7.6% (4.68–5.05 GHz) with 15.55 ± 0.05 dBi gain can be obtained by the proposed antenna array. In addition, port isolation better than 28 dB and stable radiation patterns can be achieved. With the aforementioned characteristics, the proposed antenna is a good candidate for future 5G microcell communications. [ABSTRACT FROM AUTHOR]

The design of a simple ultrahigh frequency RFID (radio frequency identification) reader antenna that can operate within the North America RFID band (902-928 MHz) is studied. To generate circular polarization (CP) radiation in this band, a novel method of loading two narrow open-ended slots (slits) into an eccentric annular slot patch is proposed. To allow optimum impedance matching with enhanced CP bandwidth, the radiating patch is loaded to an L-shaped ground plane. From the experimental results, the proposed antenna can yield an impedance bandwidth (10-dB return loss) between 650 MHz to 1125 MHz, while good CP bandwidth (3-dB axial ratio, AR) from 901 MHz to 930 MHz is also attained. Furthermore, gain level and efficiency of more than 7.8 dBic and 90%, respectively, were also measured. By simply removing one of the slits, this proposed antenna can also be modified to operate within the China (840-846 MHz) and European (865-868 MHz) RFID band. [ABSTRACT FROM AUTHOR]

This paper proposes a waveguide-stripline series–corporate hybrid feed technique to ease the feed-network design for dual-polarized antenna arrays. The hybrid feed network consists of a stripline series feed network and a waveguide-stripline corporate feed network, incorporating both of their advantages in one application. Furthermore, the design can efficiently simplify the manufacturing and packaging process without any bonding postprocess. The proposed technique is realized on an $8 \times 8$ dual-polarized antenna array, and the expected performances are verified by measurement. Experimental results show that the antenna array can operate in a wide bandwidth of 13.2% with more than 40 dB isolation for dual polarization. Cross polarizations at the center frequency of 15.2 GHz are below −27 dB, and the achievable aperture efficiency is 80% for both the polarizations. This hybrid feed approach can be considered as a promising solution for efficient feed-network applications. [ABSTRACT FROM PUBLISHER]

ABSTRACT A cavity-backed antenna with low-profile, dual-polarization, and wide operating bandwidth characteristics is proposed. In this design, two orthogonally positioned triangular bowtie antennas printed on a low-cost substrate are loaded onto a square cavity, so that two orthogonal linear polarizations can be excited. By further introducing four extended ground stubs from each side of the square cavity, the proposed antenna can also acquire low-profile characteristic of approximately 0.1λ (15 mm). To achieve good impedance matching, additional circular slots are introduced into each bowtie design. The measured results show that the proposed antenna can cover a wide operating bandwidth of 62% (2.0-3.8 GHz) with a VSWR of 2:1. Besides exhibiting good isolation (>20 dB) between the two feeding ports, desirable realized gains (6.0-10.5 dBi) over the wide operation band are also demonstrated. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:724-730, 2016. [ABSTRACT FROM AUTHOR]

ABSTRACT A microstrip-fed circular slot antenna design is proposed. To excite good CP (circularly polarized) radiation, the technique of loading a cross patch (with unequal arm lengths) into the circular slot is initially applied. Here, good impedance matching can be further attained by dividing the cross patch into two equal sections with a gap loaded in between them, in which this gap will induce a capacitive loading effects on the proposed antenna. The measured results shown that the proposed antenna has 10 dB impedance bandwidth of 36.4% (2116-3124 MHz), and its corresponding CP bandwidth (along 3 dB axial ratio, AR) was 12.3% (2345-2655 MHz). In addition to that, the proposed CP slot antenna has also yielded peak gains of more than 3.3 dBic across the CP bandwidth. Detailed process of designing the proposed CP slot antenna is explicitly shown, and vital parametric studies were also conducted by simulation. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:715-720, 2016 [ABSTRACT FROM AUTHOR]

A microstrip-fed reconfigurable eccentric annular ring slot (EARS) antenna with switchable polarization is proposed. To generate orthogonal circular polarization (CP) radiations, two identical perturbation slots (PSs) are loaded below the eccentric ring-shaped slot. By incorporating a PIN diode switch across each PS, the proposed antenna can switch between left-hand CP (LHCP), right-hand CP (RHCP), and linear polarization (LP). All three polarizations have shown good impedance bandwidth and broad CP bandwidth that can cover the WLAN 2.4 GHz operating band (2400–2480 MHz). Furthermore, desirable gains of 2.49–2.82 dBi and 2.94–3.24 dBic are also exhibited at LP and LHCP/RHCP, respectively. [ABSTRACT FROM PUBLISHER]

ABSTRACT The design of a small size 50 × 50 mm2 coplanar waveguide-fed square ring slot antenna is studied. To attain circular polarization (CP) radiation with broad 3-dB axial ratio (AR) bandwidth that can cover the worldwide interoperability for microwave access 2.3 GHz (2305-2320 MHz, 2345-2360 MHz) and wireless local area network 2.4 GHz (2400-2480 MHz) bands, a novel technique of extending a C-shaped branch from the vertical monopole is proposed. Good impedance matching and CP performance was achieved by further extending a vertical tuning strip from the C-shaped branch. From the measured results, 10-dB impedance bandwidth and 3-dB AR bandwidth of 63.89% and 7.93% were achieved. Furthermore, stable gain variation of approximately 2.7 dBic and radiation efficiency of more than 85% were also exhibited across the bands of interest. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:886-891, 2015 [ABSTRACT FROM AUTHOR]

An electroconductive polyester yarn is used to fabricate an embroidered wearable monopole antenna for ultrawideband applications.Here, the structure of this embroidered antenna is a common coplanar waveguide-fed circular disk monopole antenna. From the experimental results, a 10-dB impedance bandwidth from 2.7 to 10.62 GHz is measured, while steady gains with near omnidirectional radiation patterns are exhibited within the bands of interest. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2597-2600, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27133 [ABSTRACT FROM AUTHOR]

The design of a simple UHF (ultrahigh frequency) RFID (radio frequency identification) reader antenna that operates within the 900 MHz band (902–928 MHz) is studied. To generate circular polarization (CP) radiation, a novel method of loading a semicircular slot into the main circular radiating patch is proposed. To allow optimum impedance matching with enhanced CP bandwidth, the L-shaped probe-feed technique is employed in this design. From the experimental results, besides achieving a gain level of more than 7 dBic, the proposed antenna can also yield an impedance bandwidth (10-dB return loss) from 880 to 1100 MHz, while good CP performances between 901 to 930 MHz are exhibited. To further validate the experimental results, parametric studies are also carried out via simulation. [ABSTRACT FROM PUBLISHER]

This study designed a 2\,\times\,2 circular disc array antenna with omnidirectional radiation pattern and polarization diversity. Each disc element was located above a circular slot fed by an L-shaped strip, in which the switching between two orthogonal linear polarizations (LP) and circular polarization (CP) were realized by controlling two pin diodes. To allow conical beam for all polarization senses, a meticulously designed cross-shaped feeding network is proposed, and besides showing a sufficient 10 dB return loss bandwidth that covers the 2.4 GHz band of WLAN operation, good cross-polarization level (XPL) were measured when the array operated in all available polarization senses. [ABSTRACT FROM PUBLISHER]

A compact size (15 × 40 mm2) microstrip-fed printed planar inverted-F antenna (PIFA) for mobile applications operating in the GSM/DCS/PCS/UMTS/WLAN and WiMAX bands is proposed. The main structure of this antenna is simply a double-folded PIFA with two wide open-ended radiating sections. By tuning the dimensions of the shorter open-ended section, optimum impedance matching can be achieved, while additional slits loaded to the longer open-end section are for the inclusion of universal mobile telecommunications system band. To allow shifting of the higher frequencies modes so that a wide impedance bandwidth from 5 to 6 GHz can be achieved, the technique of adjusting the position of the shorting post horizontally along the ground plane is also introduced. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2952-2960, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26429 [ABSTRACT FROM AUTHOR]

A printed compact size folded inverted-F antenna with simple configuration for mobile handset operating within the global system for mobile communication/personal communication system/digital communication system bands is initially proposed.To additionally cover the wireless local-area network frequency spectrum at 2.4 GHz, a narrow stub is protruded from the printed shorting wall. The excitation of these operating bands with desirable bandwidth is achieved by feeding a 50-Ω microstrip line to the folded radiating element through a via hole. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1045-1050, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25919 [ABSTRACT FROM AUTHOR]

A novel coplanar rectangular slot antenna with dual band operation is proposed.By loading two dissimilar inverted L-shaped slit into the rectangular radiating element, broad impedance bandwidth at both lower and upper operating bands are achieved to allow the operation for 2.4/5.2/5.8 GHz wireless local area network and 2.6/3.5/5.5 GHz worldwide interoperability for microwave access bands. The design evolution of this proposed antenna by simulation is clearly demonstrated, and a prototype was fabricated and experimentally investigated. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:987-991, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25936 [ABSTRACT FROM AUTHOR]

A novel coplanar equilateral triangular-ring slot antenna with dual frequency operation is proposed for WLAN (Wireless Local Area Network) system in the 2.4/5.2/5.8 GHz operating bands.Impedance matching for both lower and upper operating bands at 2.4 and 5.8 GHz, respectively, are achieved by capacitively loading the inner triangular patch. To excite the 5.2-GHz band, two T-shaped slits are inserted into the triangular patch. The design flow of this antenna is clearly illustrated, and a prototype was constructed and experimentally investigated. Good radiation patterns and stable gain variation are measured for all operating bands. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2775-2780, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25601 [ABSTRACT FROM AUTHOR]

The design of a square-shaped patch antenna loaded with an Olympic-like logo slot for 900 MHz UHF RFID reader applications is studied.To achieve good circularly polarized (CP) radiation, an additional narrow perturbation slot is also loaded centrally across the logo. By further applying the L-shaped probe-fed method, desirable 3-dB Axial Ratio (AR) and 10-dB impedance bandwidth of 3.72% and 30%, respectively, can be achieved. From the experimental results, gain level and efficiency of more than 6 dBic and 89% were also measured, respectively. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1358-1360, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27591 [ABSTRACT FROM AUTHOR]

The design of a compact coplanar waveguide-fed monopole antenna partially surrounded and coupled by a folded ground strip is presented. By properly tuning the gap between the monopole antenna and the ground strip, it is able to operate in the 5-GHz band for wireless application. From the experimental results, a resonant mode excited at around 5.5 GHz is observed with 10-dB bandwidth measured from 4.88 to 6.3 GHz. Good radiation patterns with near omnidirectional pattern in the azimuth plane are also observed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26330 [ABSTRACT FROM AUTHOR]

A dipole‐type millimeter‐wave (mm‐wave) antenna with directional radiation characteristics is presented. A radiating patch structure composed of a dipole‐type radiation patch and a rectangular‐shaped parasitic patch are initially investigated to achieve a wider bandwidth. To further improve the operating bandwidth and to realize a directional radiation characteristic, this radiating patch structure is top‐loaded above a conducting cavity‐backed ground structure, which has a low profile (thickness of 3 mm). The measured results show that the proposed mm‐wave antenna can achieve a wide 10‐dB bandwidth of 51.3% (29.6‐50.0 GHz) and stable gain across the desired frequency range. Furthermore, good directional characteristics over the entire mm‐wave frequency band with a compact antenna size of 0.64λ40GHz × 0.91λ40GHz × 0.43λ40GHz are also realized. Hence, it is suitable for many small size wireless mm‐wave systems. [ABSTRACT FROM AUTHOR]