Rajiv Kumar Gupta

A Compact Dual-Band Fork-Shaped Monopole Antenna for Bluetooth and UWB Applications

A simple, low-cost, and compact printed dual-band fork-shaped monopole antenna for Bluetooth and ultrawideband (UWB) applications is proposed. Dual-band operation covering 2.4-2.484 GHz (Bluetooth) and 3.1-10.6 GHz (UWB) frequency bands are obtained by using a fork-shaped radiating patch and a rectangular ground patch. The proposed antenna is fed by a 50-Ω microstrip line and fabricated on a low-cost FR4 substrate having dimensions 42 (<i>L</i>_sub) × 24 (<i>W</i>_sub) × 1.6 (<i>H</i>) mm³. The antenna structure is fabricated and tested. Measured <i>S</i>₁₁ is ≤ -10 dB over 2.3-2.5 and 3.1-12 GHz. The antenna shows acceptable gain flatness with nearly omnidirectional radiation patterns over both Bluetooth and UWB bands.

PRINTED FORK SHAPED DUAL BAND MONOPOLE ANTENNA FOR BLUETOOTH AND UWB APPLICATIONS WITH 5.5 GHZ WLAN BAND NOTCHED CHARACTERISTICS

In this article, a compact microstrip-fed printed dual band antenna for Bluetooth (2.4{2.484GHz) and UWB (3.1{ 10.6GHz) applications with WLAN (5.15{5.825GHz) band-notched characteristics is proposed. It is demonstrated that dual band characteristics with desired bandwidth can be obtained by using a fork shaped radiating patch, whereas, band-notched characteristics can be obtained by etching two L-shaped slots and two symmetrical step slots on the rectangular ground plane. The proposed antenna is simulated, fabricated and tested. The structure is fabricated on a low cost FR4 substrate having dimensions of 50mm (Lsub) £ 24mm (Wsub) £ 1:6 (H)mm and fed by a 50› microstrip line. The proposed antenna has S11 • i10dB over 2.18{2.59GHz, Bluetooth band, 3.098{5.15GHz and 5.948{11.434GHz, UWB band with WLAN band notch. The structure exhibits nearly omnidirectional radiation patterns, stable gain, and small group delay variation over the desired bands.

MIMO Antenna for Bluetooth, Wi-Fi, Wi-MAX and UWB Applications

A Multiple Input Multiple Output (MIMO) antenna consisting of two 90 - angularly separated semicircular monopoles with steps for Bluetooth, Wi-Fi, Wi-MAX and UWB applications is proposed. Initially, an array of two coplanar circular monopoles with element separation of 25mm is investigated. In this conflguration, mutual coupling is < i5dB and < i10dB over 2GHz{3GHz and 3GHz{10.6GHz, respectively. Mutual coupling is reduced by using 90 - angularly separated semicircular monopoles. With semicircular conflguration, though the mutual coupling is improved, impedance bandwidth is reduced due to reduction in electrical length. A step like structure is introduced in the semicircular monopoles, and ground plane is modifled and extended between the two elements to improve the impedance bandwidth and mutual coupling. Impedance bandwidth from 2.0GHz{10.6GHz with S21 < i20dB and i14dB is achieved over 3.1GHz{10.6GHz and 2.0{3.1GHz respectively. The antenna is fabricated using 46mm £ 37mm RT Duroid substrate. Measurement results agree with the simulation ones. Radiation patterns are stable, and correlation coe-cient is < 0:02 over 2.0{10.6GHz.

HIGH-GAIN LOW SIDE LOBE LEVEL FABRY PEROT CAVITY ANTENNA WITH FEED PATCH ARRAY

In this paper, a high gain, low side lobe level Fabry Perot Cavity antenna with feed patch array is proposed. The antenna structure consists of a microstrip antenna array, which is parasitically coupled with an array of square parasitic patches fabricated on a FR4 superstrate. The patches are fabricated at the bottom of superstrate and suspended in air with the help of dielectric rods at 0:5‚0 height. Constant high gain is obtained by resonating parasitic patches at near close frequencies in 5.725{5.875GHz ISM band. The structure with 9£9 square parasitic patches with 1:125‚0 spacing between feed elements is fabricated on 5‚0 £ 5‚0 square ground. The fabricated structure provides gain of 21.5dBi associated with side lobe level less than i25dB, cross polarization less than i26dB and front to back lobe ratio of more than 26dB. The measured gain variation is less than 1dB and VSWR is less than 2 over 5.725{5.875GHz ISM band. The proposed structures are good candidates for base station cellular systems, satellite systems, and point-to-point links.

Right-Hand/Left-Hand Circularly Polarized High-Gain Antennas Using Partially Reflective Surfaces

Single-feed, efficient, high-gain antennas using partially reflective surface (PRS) with right-hand/left-hand circular polarization (CP) are investigated. Metallic ground plane and a PRS with square patch (SP) arrays at about 0.5λ0 height form the Fabry-Perot cavity (FPC) that is fed by a circularly polarized microstrip antenna (MSA). Right-handed circular polarization (RHCP) or left-handed circular polarization (LHCP) at the MSA is obtained using a single diagonal feed and shorting posts along x- or y-axes. Constant high-gain performance is obtained by resonating feed patch (FP) and SP arrays in the same frequency band. The effect of the SP array on antenna performance is critically analyzed. Gain enhancement of 10 dB over the circularly polarized MSA is obtained by optimizing PRS structures. Antennas with different PRSs yield peak gain of 9.1-17.3 dBi, and axial ratio (AR) is less than 3 dB over the desired frequency band. Gain variation is less than 1 dB over the frequency band. Measured results validate the design concept and indicate that the proposed structures exhibit good radiation characteristics and are suitable for satellite systems.

1 x 3 Microstrip Line-fed Metal-plated Split U-shaped Omnidirectional Ultra-wideband Monopole Antenna

Abstract In this article, a parallel metal-plated split U-shaped omnidirectional ultra wideband (UWB) antenna fed by a novel 1 × 3 microstrip line is proposed. Printed monopole antennas fabricated on a substrate offer impedance bandwidth which can cover UWB. However, radiation pattern varies significantly over the bandwidth. The cross polar component increases with frequency and the pattern degrades from the desired omnidirectional characteristics. Omnidirectional radiation bandwidth can be increased significantly by decreasing the substrate thickness and using substrate material of low dielectric constant. With the use of the proposed feeding arrangement, parallel metal-plated split U-shaped monopole antenna shows omnidirectional radiation pattern. The proposed metal-plated structure using foam as dielectric is designed, fabricated, and tested. The measured VSWR is <2 over 3.1 to 10.6 GHz frequency band. The antenna offers high efficiency, stable gain, small group delay variation, and its radiation patterns indicate its suitability for UWB applications.

A COMPACT MIMO ANTENNA WITH IMPROVED ISOLATION FOR 3G, 4G, WI-FI, BLUETOOTH AND UWB APPLICATIONS

In this paper, a compact MIMO antenna with improved isolation is proposed. Elliptical slots and an SRR like structure are employed to improve the isolation. The proposed MIMO antenna structure consists of two semi-circular radiators attached to a rectangular monopole which are mirror images of each other with edge to edge spacing of 0.125λ0, where λ0 is the free space wavelength corresponding to the lowest operating frequency of the structure. Two square steps are added to the above semi-circular monopole to increase the effective path length to cover the lower frequencies. Thereafter, a semi-annular ring slot is introduced, and square steps above the semi-circular monopole are modified to curved steps to further improve the impedance bandwidth of the antenna. The mutual coupling over the wideband is reduced by placing elliptical slots and SRR like structure in the ground plane. The proposed antenna has impedance bandwidth of 2.1–12 GHz with |S21| < −20 dB over the entire frequency range. The antenna is designed and fabricated on an FR-4 substrate having overall dimensions of 38mm × 33.4mm × 1.6 mm. The measured results show a good correlation with the simulated ones. The envelope correlation coefficient (ECC) of the antenna is less than 0.02 over the entire band. The proposed MIMO antenna is an appropriate candidate for 3G, 4G, Wi-Fi, Bluetooth and UWB applications.

Compact circular ring shaped monopole UWB MIMO antenna

This paper presents a simple and a compact MIMO antenna for Ultra Wideband applications. The proposed structure contains two circular ring shaped monopoles which is kept parallel to each other. The physical separation between the radiating elements is about 0.25λ and the mutual coupling obtained is about 20 dB throughout the band. Ground slots (GS) and extended ground plane (EGP) are the means utilized to achieve high isolation. The antenna is optimized to provide more than 113.5 % impedance bandwidth below VSWR 2 (S11 < −9.5 dB) for the 2.87 GHz to 10.4 GHz band. The designed structure has length and width of 30 × 26.4 mm2 when etched on one of the sides of the cost effective FR4 substrate thickness which is of 1.6 mm. Apart from the MIMO performance metrics, which include, ECC, Diversity Gain and Mean Effective Gain, the time domain analysis, radiation and gain patterns are measured and presented too. This analysis guarantees that this antenna is suitable for ultra band MIMO applications.

Dual-band compact MIMO antenna for 3G, Wi-MAX and WLAN applications

This paper presents a compact MIMO antenna with dual band operation. S¹¹ < −9.5 dB is achieved over lower band of 2.576–3.728 GHz and upper band of 5.14–5.88 GHz which covers 2.572–2.62 GHz (3GPP), 2.6–2.69 and 3.3–3.7 GHz (4G Wi-Max) and 5.15–5.35, 5.725–5.875 GHz (WLAN) applications. Isolation techniques like ground slots and ground extension are used to achieve a S<inf>12</inf> < −20 dB in both the operating bands. The measured results of fabricated antenna structure match with the simulation results. MIMO performance parameter ECC in the lower band is < 0.02 and in higher band is < 0.04 with stable radiation pattern. The proposed antenna has dimension of 28×35×28×1.6 mm³ which makes it feasible to be used within portable devices.