Simple Feeding Structure Research Articles

Ultrawideband circularly polarized monopole antenna for millimeter‐wave applications

ABSTRACTThis letter describes the design, and measurement of an ultrawideband (UWB) circularly polarized monopole antenna for millimeter‐wave short range wireless communications applications. This antenna is comprised elliptical loop monopole antenna with modified ground plane and connected by via to another loop on the other substrate side and coupled with small loop to create UWB without discontinuity bands. The −10 dB impedance bandwidth of the antenna provides 85 GHz which extended from 15 to 100 GHz. Moreover, multiband circularly polarized antenna provides 3 dB axial ratio (AR) bandwidth extends from 20 to 30 GHz, from 35 to 45 GHz and from 55 to 75 GHz. The average gain is around 4.5 dBi while the average radiation efficiency is 80% with 15% reduction as compared to original antenna size. The compact size and simple feed structure of the designed antenna make it a low cost solution for the integrated millimeter‐wave applications for wireless communications. The antenna with and without via are fabricated and measured to show the effect of via. The HFSS, FEM‐based 3D full wave electromagnetic solver simulator from Ansys is used for the design of the proposed antennas. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:189–194, 2017

A Broadband Circularly Polarized Crossed-Dipole Antenna

A unidirectional broadband circularly polarized (CP) crossed-dipole antenna is presented in this communication. This antenna has a simple feeding structure, which uses an unequal power network. It can simply realize 90° phase shift and four equal power divisions. The study of the antenna performance with different geometric parameters has been conducted. Working band of designed antenna covers the BeiDou Navigation Satellite System, GPS, and GLNOSS bands. An optimized antenna is designed and measured, the measured results agree well with the simulated results. The results show good performance of impendence bandwidth is approximately 66.2% (1.01–2.01 GHz), the 3-dB axial-ratio bandwidth (ARBW) of approximately 41.3% (1.21–1.97 GHz). Moreover, the measured bore-sight antenna gain is stable and varying not too much, which average value is 6.0 dBic with less than 1.5-dB variation within the 3-dB ARBW.

Design of Periodic Shorting-Vias for Suppressing the Fundamental Mode in Microstrip Leaky-Wave Antennas

The design of periodic shorting-vias for suppressing the fundamental mode in microstrip leaky-wave antennas is studied in this paper. When a microstrip leaky-wave antenna is loaded with periodic shorting-vias along the centerline, the fundamental mode has a stop band in which the mode is strongly attenuated. The stop band is investigated to best match the (leaky-wave) antenna-mode region of the first higher mode. An approximate formula is derived to estimate the start of the stop band. When the fundamental mode is suppressed in the required band, a microstrip leaky-wave antenna can be efficiently fed with a simple asymmetrical feeding structure and no additional out-phase network is needed. A microstrip leaky-wave antenna fed by a coaxial probe and another one fed by a microstrip line are demonstrated. With the proper design of shorting-vias for suppressing the fundamental mode, excellent performances of the microstrip leaky-wave antennas are achieved.

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.

Compact CPW‐fed triple‐band antenna for diversity applications

A compact coplanar waveguide (CPW)-fed triple-band monopole antenna with high-band isolation for various wireless applications is presented. The proposed antenna is composed of a CPW-fed structure and a hexagon-shaped patch on which a hexagon-shaped slot is etched for covering the wireless local area network (WLAN) band (2.4/5.2/5.8 GHz), and occupies a very compact size of 26 × 25 mm2. By introducing a half-hexagon-shaped stub, additional bands can be realised covering the worldwide interoperability for microwave access (WIMAX) band (2.5/3.5/5.5 GHz). The proposed antenna has been fabricated and measured; results show a higher isolation between adjacent bands, good radiation pattern characteristics and stable gains in the operating bands. The simple feeding structure, compact size and uniplanar design make it easy to be integrated within portable devices for wireless communication.

Circularly polarized magnetic dipole antenna with shallow and embedded structure for airborne GPS applications

ABSTRACTA new circularly polarized magnetic dipole antenna with shallow and embedded structure is designed for operation at the global positioning system (GPS) L2 band. The antenna consists of two pairs of orthogonal magnetic dipoles and a simple microstrip feed structure. The four sides of the antenna are grounded with sheet metals, leading to the antenna being insensitive to the surrounding environment. It forms a closed and firm box. The proposed antenna can be integrated with the metallic aircraft without any gaps. It has a low profile of only 0.04 , where is the free‐space wavelength of the GPS L2 band (1227.5 MHz). A prototype has been designed, fabricated and found to have an impedance bandwidth of 5.92% and a 3‐dB axial‐ratio bandwidth of about 2.61% at GPS frequency of 1227.5 MHz. In addition, a model which includes the proposed antenna and a metallic aircraft is simulated. The results show that the metallic aircraft has small effect on the antenna. The antenna is suitable for airborne GPS applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:902–906, 2015

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.

Compact triband ACS-fed stepped monopole antenna with inverted-L slot for WLAN/WiMAX applications

A compact triband asymmetric coplanar strip (ACS)-fed stepped monopole antenna with inverted-L slot for wireless local area network (WLAN)/worldwide interoperability for microwave access (WiMAX) applications is proposed and investigated in this paper. The proposed antenna is composed of an ACS-fed stepped monopole and an inverted-L slot, which occupies a very compact size of 26.5 × 8 mm2 including the ground plane. By adjusting the dimensions of the stepped monopole, slot and ground plane, three desired resonant frequencies can be achieved and tuned independently. The antenna exhibits three resonances covering the 2.4/5.2/5.8 GHz WLAN bands and 3.5/5.5 GHz WiMAX bands. Details of the antenna design, simulation, and measurement results are presented and discussed. Furthermore, the proposed antenna shows nearly omnidirectional radiation characteristics and reasonable gains in the operating bands. The simple feeding structure, compact size, and uniplanar design make it easy to be integrated within the portable device for wireless communication.

Compact ACS‐fed UWB antenna for diversity applications

A compact asymmetric coplanar strip (ACS)-fed ultra-wideband (UWB) antenna for diversity applications is presented. The proposed antenna is composed of two circular radiating elements and orthogonal ACS-fed mechanisms to achieve diversity performance across the UWB from 2.66 to 11.08 GHz, and occupies a very compact size of 28.5 × 28.5 mm2. By introducing a rectangular stub diagonally between the two circular radiating elements, an interport isolation better than 15 dB is achieved. Furthermore, the proposed antenna shows nearly omnidirectional radiation patterns, stable gains and a low envelope correction coefficient. The simple feeding structure, compact size and uniplanar design make it easy to be integrated within the portable device for wireless communications with diversity operations.

Compact ACS‐fed UWB monopole antenna with extra Bluetooth band

A compact asymmetric coplanar strip (ACS)-fed ultra-wideband (UWB) monopole antenna with extra Bluetooth band for various wireless applications is presented. The proposed antenna is composed of a modified ACS-fed structure and a staircase-shaped patch for covering the UWB band (3.1-10.6 GHz), which occupies a very compact size of 32.5 × 10 mm 2 . By etching a snake-shaped slot in the staircase-shaped patch, an additional band can be realised covering the Bluetooth band (2.4-2.484 GHz). Furthermore, the proposed antenna has been fabricated and measured, and good results obtained. The proposed antenna shows nearly omnidirectional radiation characteristics, relatively consistent group delays and stable gains in the operating bands. The simple feeding structure, compact size and uniplanar design make it easy to be integrated within portable devices for wireless communication.

Compact triband ACS-fed monopole antenna employing open-ended slots for WLAN/WiMAX applications

A compact triband asymmetric coplanar strip (ACS)-fed printed monopole antenna employing open-ended slots for WLAN/WiMAX applications is proposed. The proposed antenna consists of a simple ACS-fed monopole and two different open-ended slots, which occupies a very compact size of 18.5 × 10 mm2 including the ground plane. By adjusting the dimensions of the slots, feed line, and ground plane, three desired resonant frequencies can be achieved and tuned independently. The antenna exhibits three resonances covering the 2.4/5.2 GHz WLAN bands and 3.5 GHz WiMAX band. Details of the antenna design, simulation, and measurement results are presented and discussed. Furthermore, the proposed antenna shows nearly omnidirectional radiation characteristics and reasonable gain in the operating bands. The simple feeding structure, compactness, and uniplanar design make it easy to be integrated within the portable device for wireless communication.

An Integrated Wide-Band Circularly Polarized Antenna for Millimeter-Wave Applications

This communication describes the design, integration and measurement of a compact, wide-band, circularly polarized antenna for millimeter-wave short-range communication. The antenna is comprised of a five-section square loop and a tapered feed line. This configuration is less sensitive to the fabrication issues compared to the conventional circular spiral antennas. Two samples of this antenna designed for 60 GHz are integrated in a 6 layer IC package. The measured impedance bandwidth of the antenna-in-package is over 12 GHz. Moreover, this circularly polarized antenna provides over 7 GHz of axial ratio bandwidth. The measured peak gain is around 6 dBi. The compact-size and simple feed structure of the designed antenna make it a low-cost solution for the integrated millimeter-wave radio packaging.

COMPACT TRI-BAND PLANAR MONOPOLE ANTENNA WITH ACS-FED STRUCTURE

In this paper, a compact asymmetric coplanar strip (ACS)-fed printed monopole antenna for tri-band WLAN/WiMAX applications is presented. The proposed antenna is composed of a simple monopole with the high resonant mode at 5.8 GHz, an open-ended slot embedded on the ground plane with the low resonant mode at 2.4 GHz, and a meander trip shorted to the ground with the middle resonant mode at 3.5 GHz. The three resonance frequencies of the antenna can be controlled by adjusting the geometries and the sizes of the monopole, the slot and the strip. The antenna occupies a very compact size of 22 × 12 mm 2 including the ground plane, has nearly omnidirectional radiation characteristics and reasonable gain in the operating bands. The simple feeding structure, compactness and uniplanar design make it easy to be integrated within the portable device for wireless communication.

DESIGN OF COMPACT ASYMMETRIC COPLANAR STRIP-FED UWB ANTENNA WITH DUAL BAND-NOTCHED CHARACTERISTICS

In this paper, a new design of asymmetric coplanar strip (ACS)-fed UWB planar monopole antenna with dual band-notched characteristics is presented and investigated. The proposed antenna is composed of an asymmetric ground plane, a semi-circular radiator, together with two open-ended half wavelength bow-shaped slots etched on the radiation patch. This leads to the desired dual notched bands of 3.12{3.69GHz for WiMAX and 5.51{6.01GHz for WLAN. Experimental results show that the designed antenna, with compact size of 29:5 £ 12mm 2 , has stable and omnidirectional radiation pattern, sharp reduction in gain and group delay at notched frequencies. The very simple feeding structure and compact uniplanar design make it easy to be integrated within the portable device for UWB communication systems.

COMPACT ACS-FED CIRCULAR-ARC-SHAPED STEPPED MONOPOLE ANTENNA FOR TRI-BAND WLAN/WIMAX APPLICATIONS

In this paper, a compact asymmetric coplanar strip (ACS)-fed printed monopole antenna for tri-band WLAN/WiMAX applications is presented. The proposed antenna is composed of a circular- arc-shaped stepped monopole with dual operating frequencies at 2.4/5.7GHz and a simple circular-arc- shaped strip with the third operating frequency at 3.5GHz. The three resonant frequencies of the antenna can be controlled by adjusting the geometries and the sizes of the stepped monopole, the strip and the ground plane. The antenna occupies a very compact size of 22:1£12mm 2 including the ground plane, has nearly omnidirectional radiation characteristics and reasonable gain in the operating bands. The simple feeding structure, compactness and uniplanar design make it easy to be integrated within the portable device for wireless communications.

Broadband Circularly Polarized Antenna With L-shaped Strip Feeding and Shorting-Pin Loading

A patch antenna with simple feeding structure for broadband circular polarization is proposed in this letter. The patch is first designed with horizontal L-shaped strip (HLS) feeding, which feeds the radiation patch at orthogonal orientations with 90 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> phase difference. Two minimum points can be seen in the axial-ratio (AR) curve. By loading a shorting pin to the patch, the minimum point of lower frequency moves to higher frequency, and wide AR band is obtained consequently. Measured results show that 10-dB return-loss bandwidth of 23.6% (2.09-2.65 GHz), 3-dB AR bandwidth of 17.9% (2.18-2.61 GHz), and average gain of 8.5 dBic across the operating band are achieved for the proposed antenna with a low profile of 0.09λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ( λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the wavelength in free space corresponding to 2.4 GHz).

Crescent slot antenna for 2.4/5.2/5.8 GHz wireless local area network operations

A nonconcentric crescent slot antenna design for wireless local area network (WLAN) operation is proposed. The antenna has a single radiating slot for dual-band operation and a simple feeding structure for impedance matching. It provides two 10-dB impedance bandwidths of 115 MHz (ca. 4.7% centered at 2.45 GHz) and 1130 MHz (ca. 20.5% centered at 5.5 GHz). The nonconcentric crescent slot design covers the 2400–2484 and 5150–5825 MHz bands of WLAN operations. The return loss, radiation performance, and magnetic current distributions are studied and discussed. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1081–1085, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27491

A Radial Line Slot Antenna for an Elliptical Beam

A radial line slot antenna (RLSA) with a quasi-elliptical aperture to create an elliptical beam is discussed in this paper. A simple feeding structure consisting of a coaxial feeder and two parasitic pins is designed to produce the feed pattern required for uniform illumination over the aperture. The slot length distribution in the radial direction is designed to be similar to conventional RLSAs for specified radial dimensions associated with the elliptical aperture. A 22 GHz quasi-elliptical RLSA with major and minor axes of 300 mm and 150 mm, respectively, was designed. The radiation pattern predicted by a method of moments (MoM) had 3 dB beam-widths of 2.46 and 4.9 degrees in the 0- and 90-degree cut-planes, and the directivity of 33 dBi corresponds to an aperture efficiency of 71.5%. The measured 3 dB beam-widths and the directivity agree well with the predictions. The measured antenna gain of 31.8 dB at 22.0 GHz corresponds to an antenna efficiency of 56%, while the axial ratio is 1.74 dB.

A Printed Wide-Slot Antenna With a Modified L-Shaped Microstrip Line for Wideband Applications

A printed wide-slot antenna for wideband applications is proposed and experimentally investigated in this communication. A modified L-shaped microstrip line is used to excite the square slot. It consists of a horizontal line, a square patch, and a vertical line. For comparison, a simple L-shaped feed structure with the same line width is used as a reference geometry. The reference antenna exhibits dual resonance (lower resonant frequency <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , upper resonant frequency <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). When the square patch is embedded in the middle of the L-shaped line, <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> decreases, <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> remains unchanged, and a new resonance mode is formed between <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Moreover, if the size of the square patch is increased, an additional (fourth) resonance mode is formed above <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Thus, the bandwidth of a slot antenna is easily enhanced. The measured results indicate that this structure possesses a wide impedance bandwidth of 118.4%, which is nearly three times that of the reference antenna. Also, a stable radiation pattern is observed inside the operating bandwidth. The gain variation is found to be less than 1.7 dB.

PIFA with parallel resonance feed structure for wideband operation

A simple but efficient feed structure for achieving a wide-impedance bandwidth is proposed. The feed structure operating as a parallel resonance circuit can provide controllable resonance additionally in the conventional planar-inverted-F antenna (PIFA). It was verified that the modified PIFA incorporating the proposed feed fully covers Long Term Evolution (LTE) 13, Global System for Mobile Communications (GSM) 850 and 900 bands under VSWR 3:1 with good radiation patterns.