Sanjeev Kumar Mishra

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.

COMPACT PRINTED DUAL BAND-NOTCHED U-SHAPE UWB ANTENNA

In this article, a low cost, simple, and compact printed microstrip-fed U-shape monopole ultra-wideband antenna with dual band-notched characteristics is proposed and investigated. By introducing a spiral shaped ‚/4 open stub in the microstrip feed line and a pair of L-shaped slots on the rectangular ground patch, dual band notched characteristics can be obtained respectively. The proposed antenna is successfully simulated, designed, fabricated and measured. The measured results show that the proposed antenna with dimensions of 24mm(Wsub) £ 34mm(Lsub) £ 1:6mm(H) has a large bandwidth over the frequency band from 2.75GHz to 10.6GHz with VSWR less than 2, except 3.27{4.26GHz and 5.01{5.99GHz frequency bands. The proposed antenna exhibits nearly omnidirectional radiation pattern, stable gain, and small group delay variation over the desired frequency bands.

HIGH GAIN AND LOW CROSS-POLAR COMPACT PRINTED ELLIPTICAL MONOPOLE UWB ANTENNA LOADED WITH PARTIAL GROUND AND PARASITIC PATCHES

In this paper a low cost, high gain, low cross-polar and compact edge feed printed elliptical antenna with a partial ground plane and parasitic patches is proposed and investigated. The proposed antenna is fabricated on a 1.6mm thick FR4 substrate with dielectric constant of 4.4 and loss tangent of 0.025. The total planar area of the proposed antenna (L £ W) is 28 £ 24mm 2 . Both the simulated and experimental result shows that the proposed antenna provides a frequency range compatible with the ultra-wideband (UWB) standard, i.e., 3.5GHz{12GHz frequency band. The radiation pattern produced by the proposed antenna is approximately omnidirectional with in- phase excitation of Surface waves resulting in less cross-polarization level (less than 20dB) compared to its co-polar component for the entire impedance band width. The maximum measured gain for the fabricated antenna is around 6.27dBi with an average e-ciency of above 90% throughout the bandwidth. A linear phase response (phase of S21) accompanied by a constant group delay of 1ns throughout the measured bandwidth makes the proposed antenna a good candidate for UWB applications.

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.

Compact Bluetooth/UWB Dual-Band Planar Antenna With Quadruple Band-Notch Characteristics

A compact Bluetooth/Ultrawideband (UWB) dual- band planar antenna with quadruple band-notch characteristics is presented. The proposed structure consists of a UWB semi-elliptical planar monopole, attached to an approximate trapezoidal spiral for 2.45-GHz Bluetooth application. The proposed antenna utilizes rectangular resonant spiral structures for rejection of quadruple frequency bands, i.e., WiMAX (3.3-3.6 GHz), WLAN (5.15-5.35, 5.725-5.825 GHz), and ITU 8 GHz. These resonant spirals are capacitively coupled with the microstrip feedline. The band-notch characteristics are controlled by changing the effective length of the spirals along with coupling gaps between the feedline and the spirals. The proposed antenna also achieves sharp reduction in the gain and efficiency at all the notch frequencies. However , at the passbands, the gain and radiation efficiency are almost stable. A good agreement between the simulated and measured results shows that the proposed antenna with surface dimensions of 24 × 17 mm2 is suitable for Bluetooth/UWB dual-band applications.

Cross-Configured Directional UWB Antennas for Multidirectional Pattern Diversity Characteristics

A cross configuration of directional ultrawideband (UWB) antennas for multidirectional pattern diversity characteristics is presented. Initially, a printed UWB circular monopole having an asymmetric curve shaped CPW feed is designed as a base antenna for obtaining a directional radiation pattern, direction of which remains fairly same for the entire UWB. This base antenna is attached to similar antennas, in a four element cross-configuration to achieve multidirectional pattern diversity characteristics. The proposed structure provides high inter-element isolation of more than 20 dB, with an impedance bandwidth of 19.7 GHz, i.e., 1.3 GHz to 20 GHz. Transmission and diversity characteristics of the proposed antenna are analyzed. Good agreement between simulated and measured results indicates that the proposed antenna is suitable for UWB pattern diversity applications.

BLUETOOTH/UWB DUAL-BAND PLANAR DIVERSITY ANTENNA WITH WiMAX AND WLAN BAND-NOTCH CHARACTERISTICS

In this paper, a stage wise realization of compact Bluetooth | UWB dual-band diversity antenna with WiMAX and WLAN band-notch characteristics is presented. The proposed structure consists of two co-planar semicircular dual band-notch monopole antennas, mounted with planar spiral. Individual antenna conflguration provides an impedance bandwidth (VSWR < 2) for dual- band i.e., both Bluetooth and UWB bands. For dual band-notch characteristic, two sets of spirals are capacitively coupled with the feed line of antenna. This conflguration provides band-notch (VSWR < 2) for WiMAX i.e., (3.3{3.6GHz) and WLAN (5.13{5.85GHz) bands. For enhancing reception capabilities of the proposed structure, twin coplanar antennas are used to fulflll diversity requirements. However, due to coplanar and close proximity to each other, there is high possibility of mutual coupling between coplanar antenna elements. To address the mutual coupling between elements, cross-strip variable- sized frequency selective structures are used. Antenna diversity of the proposed structure is validated by measuring radiation pattern characteristic and envelop co-relation factor (ECC). A good agreement between measured and simulated responses ensures that the proposed diversity antenna can be used for interference free Bluetooth/UWB dual-band applications.

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.

Effect of superstrate height on gain of MSA fed Fabry Perot Cavity antenna

This article highlights the effect of superstrate height on gain of MSA fed Fabry Perot Cavity (FPC) antenna. The FPC antenna structure consists of a microstrip antenna, which feeds an array of square parasitic metal patches fabricated on a FR4 superstrate. These patches are good reflector of microwave frequency and therefore are used to enhance the reflection coefficient and the gain. Field amplitude and phase depend on dimensions and spacing between parasitic patches. Antenna gain can be further increased by increasing the superstrate height. However, differential gain improvement decreases with superstrate height. High gain is achieved by placing superstrate layer at about integral multiple of half wavelength above the ground plane. Structures are designed, fabricated and tested. Measured VSWR is less than 2 over 5.725–5.875 GHz, ISM band. The analysed structures can be packaged inside an application platform.