Ultra-wideband Frequency Band Research Articles

A bandwidth and gain enhancement for microstrip antenna based on metamaterial

AbstractAn ameliorated ultrawide band (UWB) and high‐gain microstrip antenna based on planar metamaterial is presented and discussed in this paper. The proposed antenna with a compact size of 32 × 28 × 0.794 mm3 has mesh‐shaped patch and patterned ground plane with crossed strip gaps. By means of novel planar metamaterial structure, impedance bandwidth and gain own a significant improvement. The simulations show that the antenna has a super‐wide band (less than −10 dB), from 3.06 GHz to 36.4 GHz, covering the entire UWB frequency band (from 3.1 GHz to 10.6 GHz) set by FCC. Within the operating band of concern, the antenna gain can reach as high as 8.02 dB. Due to the surface wave coming from the patterned patch and ground plane, the antenna presents end‐fire directional radiation in the higher frequency region. To validate the simulation results, a prototype is fabricated and measured. And the measured results are in good agreement with the simulation results. It is obvious that advantages mentioned above will enable the proposed antenna to be well applied in the short‐range wireless communication system.

Conceptual design and automated optimisation of a novel compact UWB MIMO slot antenna

In this study, a concept and design optimisation procedure of a novel compact multiple-input-multiple-output (MIMO) slot antenna is presented. As the authors' primary objective is to achieve a better utilisation of the available space, individual ultra-wideband (UWB) antennas are constrained to a triangular shape and optimised for a reduced size. Subsequently, the MIMO structure is assembled using the previously designed radiators in orthogonal arrangement. Low computational cost of antenna geometry parameter adjustment is maintained by employing surrogate-assisted optimisation involving variable-fidelity electromagnetic simulation models. The footprint of the optimised MIMO design is only 630 mm 2 and features very good isolation in the entire UWB frequency band. Numerical results are confirmed by experimental measurements of the fabricated prototype.

Wideband multiple‐input–multiple‐output dielectric resonator antenna

A two-element multiple-input–multiple-output (MIMO) dielectric resonator antenna having wideband characteristics is presented. The wideband operation is achieved by using a mushroom shaped dielectric resonator excited by a conformal trapezoidal patch. In order to realise two-element MIMO configuration, two wideband radiators are arranged orthogonally which offers polarisation diversity. The measured bandwidth (VSWR ≤ 2) for Port1 is 61% (5.08–9.50 GHz), whereas for Port2 it is 65% (4.89–9.61 GHz). The isolation between the two ports is better than 20 dB for the desired frequency band. The antenna exhibits broadside radiation with cross polar level below 15 dB. The peak gain of antenna varies from 3.34 to 7.40 dBi at Port1 and from 2.34 to 7.9 dBi at Port2. Moreover, the various MIMO performance metrics including envelope correlation coefficient (ECC), diversity gain, channel capacity loss and total active reflection coefficient are investigated. The ECC is less than 0.01 and capacity loss is under 0.5 bps/Hz throughout the operating bandwidth. The results confirm that the antenna offers effective MIMO/diversity performance. The proposed antenna can be suitable for WLAN and upper ultra wideband frequency band applications.

Wideband stacked maltese cross‐shaped DR antenna for WiMAX and WLAN applications

A new maltese cross-shaped dielectric resonator (DR) antenna is presented and analysed as a wideband radiator. The antenna comprises of maltese cross-shaped DR, arranged in a stacked configuration and centrally fed by a coaxial probe. The proposed antenna radiates such as an electric monopole, generating omnidirectional linearly polarised fields. Three modes: namely, TM01δ , TM02δ , and TM03δ are simultaneously excited and merged in the composite structure to obtain a wide bandwidth of 59.5% [for voltage standing wave ratio≤2], covering frequency range from 3.15 to 5.82 GHz. The radiation pattern of the proposed antenna is fairly stable throughout the operating band with the measured peak gain varies from 3.27 to 6.09 dBi. A prototype of the proposed antenna is built and tested. Both the simulations and experimental results are presented and discussed. The proposed antenna is suitable candidate for worldwide interoperability for microwave access (3.5 GHz) and wireless local area network (3.65 GHz/4.9 GHz/5 GHz) applications. Moreover, it can also be used for lower European ultra-wideband frequency band (3.4–5 GHz) applications.

Compact UWB–MIMO antenna with quad-band-notched characteristic

With quad-band-notched characteristic, a compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna is introduced in the paper. The UWB–MIMO system has two similar monopole elements and occupies 30 × 45 mm2. By inserting two L-shaped slots, CSRR and C-shaped stubs, four notched bands are achieved (3.25–3.9, 5.11–5.35, 5.5–6.06, and 7.18–7.88 GHz) to filter WiMAX, lower WLAN, upper WLAN, and X-band. Meanwhile, the isolation is obviously enhanced with three metal strips on the ground plane. Results indicate that the antenna covers UWB frequency band of 3.1 – 10.6 GHz except four rejected bands, isolation of better than −18 dB, envelope correlation coefficient of <0.02, and good radiation pattern, thus making it useful for UWB systems.

Compact isolation-enhanced UWB MIMO antenna with band-notch character

In this paper, a compact multiple-input multiple-output antenna with band-notched characteristic is presented for Ultra-Wideband (UWB) applications. Two orthogonally placed radiator elements excite the same open slot which consists of two connected T-shaped slots on the ground plane. Such orthogonal structure easily achieves good diversity performance. To enhance isolation of the lower band, a fork-shaped slot is notched on the ground between two radiators, and the mutual coupling reduces to −20 dB below for the entire UWB frequency band. By slitting open-ended quarter-wavelength L slots on the radiator elements, the rejection bands are achieved. The compact size of the antenna is only 30 × 30 mm2, and the antenna prototype is fabricated and measured. Measured results indicate that a wide-impedance bandwidth, which is from 2.85 to 11.9 GHz with rejection band of 5.1–6 GHz, is achieved, and the envelope correlation coefficient is below 0.008, which are competitive for portable UWB devices.

A compact planar self-affine sierpinski carpet fractal monopole antenna with band notch characteristics for ultra wideband communications

This paper presents a novel compact planar self-affine sierpinski carpet fractal monopole coplanar waveguide (CPW) fed ultra-wideband (UWB) antenna with improved gain, radiation efficiency and a sharp band-notched characteristics for the rejection of interfering WLAN (5.15---5.825 GHz) assigned for IEEE 802.11a narrow band communication system. The significant improvements in gain and radiation efficiency are achieved by the introduction of carpet fractals in the radiating circular patch. The antenna covers the entire UWB frequency band (3.1---10.6 GHz) with voltage standing wave ratio (VSWR) ≤ 2 which depicts optimum impedance matching of the proposed antenna structure. The antenna occupies a compact size of 36 × 41 mm2 and band rejection is achieved by embedding compact C--shaped slots with folded arms on the ground planes of the CPW feed lines which yield a very sharp notch for WLAN band. The band rejection is demonstrated by a high value of VSWR around notch frequency. Compact self-affine sierpinski carpet fractals are introduced in the radiating circular patch to improve performance of the UWB antenna. The proposed fractal antenna exhibits improved gain that varies from 2 to 6 dBi and optimum radiation efficiency which varies from 85 to 99.9 % over the UWB frequency range. The gain and radiation efficiency are suppressed with strong dips at the desired rejection WLAN band. Omnidirectional radiation characteristic is achieved over UWB frequency range which supports the uniform transmission of signal irrespective of the orientation of the antenna direction.

Gain enhancement of the Vivaldi antenna with band notch characteristics using zero-index metamaterial

In this letter, a tapered slot ultrawide band (UWB) Vivaldi antenna with enhanced gain having band notch characteristics in the WLAN/WiMAX band is presented. In this framework, a reference tapered slot Vivaldi antenna is first designed for UWB operation that is, 3.1–10.6 GHz using the standard procedure. The band-notch operation at 4.8 GHz is achieved with the help of especially designed complementary split ring resonator (CSRR) cell placed near the excitation point of the antenna. Further, the gain of the designed antenna is enhanced substantially with the help of anisotropic zero index metamaterial (AZIM) cells, which are optimized and positioned on the substrate in a particular fashion. In order to check the novelty of the design procedure, three distinct Vivaldi structures are fabricated and tested. Experimental data show quite good agreement with the simulated results. As the proposed antenna can minimize the electromagnetic interference (EMI) caused by the IEEE 802.11 WLAN/WiMAX standards, it can be used more efficiently in the UWB frequency band. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:233–238, 2016

UWB loop antenna with stable broadside radiation characteristics

ABSTRACTIn this article, a circular loop antenna with stable broadside radiation characteristics for ultrawideband (UWB) applications is proposed. It consists of a circular loop and circular sectors, and the circular sectors are used to directly match a 50‐Ω feed line over a UWB frequency band. The geometry of the proposed antenna is optimized to cover the 3.1–10.6 GHz UWB frequency band with stable broadside radiation patterns. The input impedance and voltage standing wave ratio (VSWR) characteristics of three different structures (a center‐fed circular loop with thin strips, a structure with circular sectors as an end‐truncated semicircular dipole, and the proposed loop antenna with circular sectors) are compared. The optimized proposed antenna is fabricated on a Teflon substrate. It exhibits a measured impedance frequency band of 3.08–12.27 GHz (120%) for a VSWR < 2, which ensures operation in the UWB band. Measured broadside gain is 3.0–7.0 dBi, and stable broadside radiation patterns are observed in the entire UWB band. Measured group delay remains almost constant with a variation of less than ±0.5 ns for the face‐to‐face orientation, and this indicates good time domain performance of the antenna. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2515–2519, 2015

ACS‐fed UWB‐MIMO antenna with shared radiator

A novel asymmetric coplanar strip (ACS)-fed multiple-input–multiple-output (MIMO) antenna working in the ultra-wideband (UWB) frequency band with a shared radiator is discussed. The proposed antenna is composed of a radiator which is shared by two antenna elements in order to achieve a very compact size of 26 × 26 mm2. By etching an I-shaped slot in the radiator and attaching a rectangular patch on the back, the operating bandwidth is broadened and a high isolation between the two antenna elements is realised. The stub from the ground also has a great effect on the return loss and isolation. The measured results show that the working frequency band of the MIMO antenna covers 3.1–10.6 GHz with an isolation of more than 15 dB. Furthermore, the simple feeding structure and compact size could enable the proposed antenna to be used in portable devices.

A novel CPW‐fed antenna with dual band‐notched charectrestics for UWB applications

ABSTRACTIn this article, a coplanar waveguide fed (CPW‐fed) ultrawideband (UWB) antenna with dual band‐notched characteristics is presented. Using two diamond‐shaped stepped impedance resonators, two notched bands are obtained. The simulation and measurement results show that proposed antenna covers the frequency band between 2.85 and 11 GHz (118 ), defined by VSWR < 2. The proposed antenna has a total size 20 × 20 × 1.6 mm3 and performed at the whole UWB with dual notched bands at WiMAX (3.4–3.6 GHz) and WLAN (5.15–5.85 GHz). The proposed antenna has a desirable VSWR level; radiation pattern characteristics for UWB frequency band rang. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2391–2394, 2015

Design of band‐notched ultra wideband antenna for indoor and wearable wireless communications

Design of a tapered-slot ultra wideband (UWB) band-notched wearable antenna is presented in this study. The antenna operation covers the whole UWB frequency spectrum of 7.5 GHz ranging from 3.1 to 10.6 GHz, while rejecting the wireless local area network operation at 5.25 GHz band. The performance of the antenna is analysed through simulations and validated through measurements. The antenna makes use of ultra-thin liquid crystal polymer (LCP) substrate. The presented return loss and radiation pattern results show that the antenna offers excellent performance in the UWB frequency band in free space. Use of the LCP substrate makes the antenna to efficiently mitigate the bending effects. Moreover, the antenna performs well in on-body configurations and its working is little affected in adversely hot and humid weather conditions. Furthermore, it offers good on-body communication link and pulse fidelity. These features make the proposed antenna design a well-suited choice for hand-held and wearable UWB applications.

COMPACT 4-PORT ACS-FED UWB-MIMO ANTENNA WITH SHARED RADIATORS

A compact 4-port asymmetric coplanar strip (ACS)-fed MIMO antenna working in the ultra-wideband (UWB) frequency band with two shared radiators is presented in this paper. The proposed antenna is composed of two radiators, and each radiator is shared by two antenna elements in order to achieve a very compact size of 36× 36mm2. By etching two I-shaped slots in the radiators and attaching a rectangular patch on the back, the operating band width is broadened, and the isolation between any two antenna elements is enhanced. The stub of the ground also has great effect on the return loss and isolation. The working frequency band of the MIMO antenna covers 3.1–10.6 GHz with isolation over 15 dB between any two antenna elements. Furthermore, the proposed antenna with a simple feeding structure and compact size makes it possible to be used in portable devices.

An Ultrawideband to Dual-Band Switchable Antenna Design for Wireless Communication Applications

A switchable planar monopole antenna operating in ultrawide band (UWB)and dual-band mode is demonstrated. The switching is triggered with a photoconductive semiconductor switch triggered by light emitting diode. In the switched-off state, the antenna operates in the dual-band/UWB mode, while in the switch-on state the configuration converts to a dual-band antenna due to the extended ground plane. The measured and simulated results show that the dual-band/UWB mode entirely covers the UWB frequency band and the 2.4 GHz wireless local area network WLAN, while the dual-band mode represents a dual-band antenna operating at WiMAX and X-band Satellite communication bands.

Design of a Compact Bluetooth and UWB Antenna for Wireless Communications

A compact and planar dual band antenna for Bluetooth and ultra-wideband (UWB) is presented. The antenna exhibits a dual band operation covering Bluetooth (2.4-2.484 GHz) and UWB (3.1-10.6 GHz) frequency bands. It is composed of a semi-circular and an L-shaped strip and fed by a microstrip line and built on a FR4 substrate with only 23 × 35 mm2surface area. Details of the antenna design and measured results are presented and discussed.

Cross shaped slot printed UWB monopole antenna with notch function

In this paper wehave investigated and proposed a printed modified circular disc Ultra-Wideband (UWB) monopole antenna with cross-shaped slot in radiating patch having a notch function. The proposed antenna covers the entire UWB band (i.e., 3.1 to 10.6 GHz) except frequency band of IEEE 802.11a (i.e., from 5.15---5.83 GHz). In particular we have simulated modified circular disk monopole antenna with cross-shaped slot, the notch frequency can be adjusted by the changing the position of the cross-shaped slot in the radiating patch. Here simple rectangular microstrip lines are used for feeding the printed monopole antennas. This UWB monopole antenna designed works well for the whole UWB frequency band 3.1---10.6 GHz from the HFSS simulation results.

Printed planar circular radiating patch ultra wideband antennas

In this paper we have investigated printed circular disc monopole antenna, which is basically printed microstrip antenna with etched ground plane for ultra-wideband (UWB) applications. In particular we have simulated circular disc monopole antenna with etched ground plane. Simple rectangular microstrip line is used for feeding the printed monopole antenna and which is having impedance of 50 Ω. This designed circular disc UWB monopole antenna works well for the whole UWB frequency band 3.1---10.6 GHz.

Differential‐fed UWB microstrip antenna with improved radiation patterns

A differential-fed microstrip antenna, which is characterised with an ultra-wideband (UWB) of 120% (3–12 GHz), improved radiation patterns, stable gains and compact size, is proposed. Two symmetrical trapezoid-shaped slots and four triangle-cut corners on the ground are used to improve the impedance matching over the UWB frequency band. To clarify the improved radiation characteristics, the simulated 3D radiation patterns of the proposed antenna are also shown. The measured results show that, in the entire frequency band, the designed antenna exhibits a stable radiation pattern and the gain variation is < 2.5 dB. Furthermore, the polarisation purity is increased compared with the conventional ones, especially in the high-frequency band.

Analysis and review on usage of broadband techniques in design of printed antennas for UWB communications

In this paper we have investigated on broadband antennas and done comprehensive study on effective utilization and usage of broadband techniques in the design of printed antennas for broadband communications. Here the microstrip line fed circular and semicircular printed monopole antennas are chosen for well understanding and various broadband techniques are applied in order to achieve ultra wideband (UWB), at the same we explained how there broadband techniques are employed in getting such a huge bandwidth. In particular we have simulated circular patch monopole antenna and then after etched some part of the radiating patch and ground plane in order to get broadband for UWB communication. While doing simulation study, a simple rectangular microstrip line is used for feeding the printed antennas. In this paper we have give extensive review on utilization of broadband techniques in the design of UWB antennas. Finally the proposed antennas are having frequency bandwidth under ?10 dB return loss is ranging from 3 to 15 GHz. These printed monopole antennas work well for the whole UWB frequency band 3.1?10.6 GHz .

Dual polarized microstrip patch antennas for ultra‐wideband applications

ABSTRACTThis article presents a novel design of dual polarized microstrip patch antennas for ultra‐wideband (UWB) applications. Two antennas are designed for different frequency band of UWB. Both antennas are loaded together and the combined antenna is designed for the entire UWB. The designed antenna is optimized using CST Microwave Studio simulator. The antennas are fed by a 50‐Ω coaxial probe. Both antennas are fabricated and measurement of return loss and radiation pattern is performed. The VSWR 2:1 bandwidth of individual designed Antenna I and Antenna II is 3.1–5.2 GHz and 4.9–11.5 GHz, respectively. The comparison between simulated results and measured results shows good agreement. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2174–2179, 2014