Tapan Mandal

AN OPTIMAL DESIGN OF CPW-FED UWB APERTURE ANTENNAS WITH WIMAX/WLAN NOTCHED BAND CHARACTERISTICS

In this paper, a printed slot antenna fed by a co-planar waveguide for ultra wide bandwidth (UWB) with dual notch bands has been presented and discussed. The band notches are realized by etching one C-slot resonator inside a plaque shape exciting stub as well as symmetrically adding a pair of open-circuit stubs at the edge of the slot resulting in dual stop band flltering properties for WiMAX, WLAN application. Surface current distributions are used to analyze the efiects of the slot and open circuit stub. The proposed antenna is fabricated and experimental results show that it has an impedance bandwidth of 2.6{14.34GHz for VSWR • 2, except dual frequency stop-bands of 3.3{3.7, 5.04{6.0GHz. From the simulation results, it is observed that the radiation patterns are omnidirectional in the H- plane and dipole like nature in the E-plane. The gain varies from 3.7dB to 5.7dB over the whole UWB region excluding at notch bands.

Microstrip feed spanner shape monopole antennas for ultra wide band applications

An optimized design for the spanner shape regular hexagonal monopole (RHM) patch antennas has been reported to yield ultra wide band (UWB) impedance bandwidth. Impedance and radiation characteristics are presented and discussed. From the results, it has been observed that, the impedance bandwidth, defined by 10 dB return loss, can reach a value of 8.63GHz. A rectangular slit in the radiating patch is used to reduce the lower-edge frequency resulting in improved bandwidth. This technique yields the ability to construct a smaller antenna in comparison to a simple printed planar monopole antenna for a given frequency range. The printed metallic patch is defected for increasing the operating bandwidth. The antennas considered in this paper operate between 2.95 GHz to 11.58 GHz, making them suitable for numerous DECT, WLAN, remote sensing, radar, imaging, localization and medical applications. The etched area of the antenna can be used for communication circuit components.

A COPLANAR WAVEGUIDE FED ULTRA WIDEBAND HEXAGONAL SLOT ANTENNA WITH DUAL BAND REJECTION

In this paper a printed regular hexagonal slot antenna with a hexagonal stub fed by a coplanar waveguide line has been considered for ultra wide bandwidth. This antenna is then modifled to obtain dual band rejection. The Wireless Local Area Network (WLAN) and Wireless Microwave Access (WiMAX) band rejections are realized by incorporating a C-shape slot within the exciting stub as well as a couple of Z-shape open circuit stubs symmetrically inserted at the edge of the slot. The length and width of the C-shape slot and Z-shape stub ofier su-cient freedom for selecting and shifting the notch bands. Magnitude of S11, impedance, gain and radiation characteristics of them are studied and discussed here. From the measured results, it has been observed that the impedance bandwidth, deflned by magnitude of S11 6 i10dB, reaches a value of 8.18GHz (2:96 » 11:14GHz) except dual frequency stop bands of 3.28{3.7GHz and 5.1{5.90GHz. From the experimental results, it is observed that the radiation patterns are omnidirectional in the H-plane and dipole in nature in the E-plane. The antenna gain varies from 4.8dB to 5.3dB over the whole operating band excluding the notch bands. Surface current distributions are used to analyze the efiects of the C-slot and Z-shape stub. Measured group delay has very small variation within the operating band except notch bands and hence the proposed antenna may be suitable for UWB applications.

Design of a CPW-fed UWB printed antenna with dual notch band using mushroom structure

A coplanar waveguide-fed planar hexagonal monopole ultra-wideband antenna with dual-band rejection characteristics is proposed in this paper. The desired notch frequencies at 3.5 and 5.5 GHz are realized by incorporating mushroom structures. The input impedance and surface current distributions are used for analysis and explanation of the effects of mushroom cells. The prototype and proposed antennas are fabricated and tested. From the measured results, the proposed antenna provides an operating band of 2.81–14.32 GHz for 2 ≤ voltage standing wave ratio (VSWR), while the dual-band stop function is in the frequency bands of 3.3–3.7 GHz and 5.10–5.88 GHz. Moreover, the antenna model also exhibits constant group delay and linear phase in the pass band. The proposed antenna has appreciable gain and efficiency over the whole operating band except the notch bands.

Design and analysis of annular ring-based RIS and its use in dual-band patch antenna miniaturization for wireless applications

Abstract This paper proposes the design of a Reactive Impedance Surface (RIS) which comprises a 5 × 5 array of grounded unit cells. The unit cells have annular ring structures on their top surfaces. A detailed analysis of the unit cell leading to its impedance characteristic is presented and validated with simulated results. The RIS exhibits inductive impedance below 4.92 GHz. Next, the RIS is used as the ground of a dual-band patch antenna instead of a metallic ground for the purpose of miniaturization. As a result, the lower resonant frequency of the antenna is lowered from 3.36 to 2.4 GHz exhibiting 28.6% miniaturization. The higher resonant frequency is decreased from 4.77 to 3.43 GHz exhibiting 28.1% miniaturization. The theory of antenna miniaturization using RIS is also discussed. The lower and higher resonant frequencies of the miniaturized antenna correspond to the WiFi and WiMAX frequencies, respectively. The gain and efficiency at these two frequencies are significant and radiation patterns are stable with low cross- polarization level. Hence, the proposed structure can be used for practical wireless applications.

Ultra-wideband coplanar waveguide-fed hexagonal slot antennas with WLAN band rejection

In this paper, printed regular hexagonal slot antenna fed by a coplanar wave guide line has been presented for ultra wide bandwidth. The hexagonal shape stub is used. The antenna is then modified to possess band rejection at the wireless local area network (WLAN) (5.1–5.8 GHz) by a C-shape slot within the exciting stub. The length and width of the C-shape slot offer sufficient freedom for selecting and shifting the notched band. VSWR, impedance, gain and radiation characteristics are presented and discussed. From the results, it has been observed that, the impedance bandwidth, defined by 2≤VSWR, can reach a value of 6.5GHz (3.1∼9.6GHz), while stop bands of 5.15 to 5.8 GHz. The proposed antenna gain varies 4 dB to 5.3 dB over the whole operating band excluding the notch band. Surface current distributions and transmission line model are used to analyze the effect of the slot.

Bandwidth enhancement of microstrip antennas using additional gap-coupled hexagonal shape resonators to the radiating edges

In this paper, the hexagonal shaped microstrip antennas (MSA) with defected ground plane and gap coupled multi-resonators are proposed and studied for different di-electric constant. The hexagonal shape structure occupies less area and is suitable for compact antenna design. The results showed gradual improvement in impedance bandwidth from 460 MHz to 2.21 GHz with frequency variation from 8 GHz to 7.96 GHz in case of substrate with di-electric constant 4.4. A sudden improvement of impedance bandwidth from 2.19 GHz to 3.75 GHz with frequency variation from 14.32 GHz to 10.5 GHz is observed by just lowering e r to 2.62.

Bandwidth Enhancement of Stacked Microstrip Antennas Using Hexagonal Shape Multi-resonators

In this paper, wideband multilayer stacked resonators, combination of planner patches and stacked with defected ground plane in normal and inverted configuration are proposed and studied. Impedance and radiation characteristics are presented and discussed. From the results, it has been observed that the impedance bandwidth, defined by 10 dB return loss, can reach an operating bandwidth of 746 MHz with an average center operating frequency 2001 MHz, which is about 32 times that of conventional reference antenna. The gain of studied antenna is also observed with peak gain of about 9 dB.