Development of Band Reject Filter to Mitigate the effect of WLAN in UWB Receivers

This paper is about a dual band single notch filter to eliminate the effect of WLAN in UWB range. A novel square resonator with interdigital coupling at both sides plays a key role in this filter design. Design and EM Simulation of the dual band notch filter's characteristics are discussed in this paper. The proposed dual band notch filter produces excellent bandwidth from 2 GHz to 5 GHz and from 5.5 GHz to 8 GHz. The filter rejects the band of frequency from 5 GHz to 5.5 GHz which is very narrow band in which the filter eliminates the effect of WLAN (IEEE 802.11a). Also the out band performance of the proposed dual band filter meets the requirement of FCC's mask. The simulation analysis of the proposed filter is performed by electromagnetic solver. The return loss, insertion loss, group delay and phase of the filter are simulated and their performances are analyzed. The overall dimension of the filter is achieved to be 39mm x 3.2mm x 1.6mm on accounting the above features. The fractional bandwidth of the notch filter is calculated from the bandwidth and the center frequency and it is obtained about 115%. The S parameter results of the filter such as return loss (S11) in stop band is about -24 dB and insertion loss (S21) is about -28 dB is obtained

Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

Miniaturised and reconfigurable planar filters for ultra-wideband applications

An increasing demand for electromagnetic spectrum has resulted from the emergence of feature-rich and faster throughputs wireless applications. This necessitates the developments of dynamic reconfigurable or multifunctional systems to better exploit the existing spectrum. Future wireless devices will be expected to communicate over several bands with various other devices in order to fine tune the services they provide to the user. Each band may require a separate RF transceiver and such modern wireless multi-band multi-mode communication systems call for high performance, highly integrated compact modules. Since the Federal Communications Commission (FCC) released the unlicensed frequency band 3.1-10.6 GHz for ultra-wideband (UWB) commercial communications, the development race for commercialising UWB technology has seen a dramatic increase around the world. The aim of this research is to develop reconfigurable planar microwave filters for ultrawideband applications. The project investigates some key design issues of reconfigurable filters, which are being observed constantly in the latest development and realisation of microwave filters. Both analytical and numerical methods are performed to construct a realistic and functional design. Two different types of frequency reconfigurability are investigated in this thesis: discrete (e.g. PIN diode, Optical switch) and continuous (e.g. varactor diode). Using the equivalent circuits and considering the direct coupled filter structure in most cases, several topologies with attractive features are developed for future communication systems. The proposed works may be broadly categorised into three sections as follows. The first section explores a square ring shape close loop resonator along with an opencircuited stub in the symmetry plane. To realise a reconfigurable frequency states within the same spectrum, an innovative approach is developed for this case. An optical or photoconductive switch, comprised of a silicon die activated using near infrared light is investigated as a substitute of PIN diode and performances are evaluated to compare the feasibilities. In addition, a in-band interference rejection technique via externally coupled Tshape resonator is shown. However, it is observed that both structures achieve significant size reductions by utilising the inner part of the resonators. To improve the filter selectivity, a convenient design approach generating a pair of transmission zeros between both passband edges and a single zero in the stop band for harmonic suppression is discussed in the second section. Moreover, the development of notched rejection bands are studied and several novel methods to create a single and multiple notched bands employing the square ring shape structure are proposed. On inspection, it is found that the notch structure can be implemented without deteriorating the filter performances. The discussions are supplemented with detailed design examples which are accompanied by theoretical, simulated and experimental results in order to illustrate the filter development process and showcase practical filter performance. The third section reveals a novel highly compact planar dual-mode resonator with sharp rejections characteristics for UWB applications. A bandwidth reconfiguring technique is demonstrated by splitting its even-mode resonance. Filter structure with the dual-mode resonator is shown to have a relatively wide tuning range, significantly low insertion loss and a constant selectivity along with frequency variations in comparison to similar published works. Finally, the earlier dual-mode structure are modified to realise a dual wideband behaviour. A detail analysis with comprehensive design procedures is outlined and a solution for controlling the frequency bandwidths independently according to the application interest is provided. In line with the previous section, experimental verification is presented to support and supplement the discussions

Enhanced Design Of Electronically Reconfigurable Integrated Microwave Filter And Antenna For Wireless Communication Systems

The reconfigurable integrated filter and antenna is one of the major interest for researchers due to the potential significant advantages compare to the typical standard integrated structure. The growth in reconfigurable integrating technology is not limited to a single tunable parameter such as operating frequency, bandwidth and attenuation but it can be combination parameters depending on the applications. There are many techniques have been developed to achieve adaptable reconfigurable integrated filter and antenna but majorities of the reconfigurable designs are focused on a single element either on an antenna or the filter. Thus, it limits the tunable range and flexibility response of the reconfigurable design will be a challenging task. On the other hand, developing a Ultra-Wideband (UWB) antenna is one of the crucial components for UWB communications systems and has been widely studied for many years. Moreover, the reconfigurable UWB designs can be developed the desired filtering antenna which can reject unwanted signal interferences. However, most of these techniques produce excessive band rejection, which leads to reject desired frequencies, thus producing a narrowband notch characteristics is a challenging issue. Therefore, the aim of this research is to design novel structure of reconfigurable integrated technique of planar structure which promises a new potential functionality of the microwave devices. Two designs approach were introduced which is reconfigurable SIW filter and antenna and reconfigurable dual band-notched UWB antenna using FR-4 substrate and Roger Duroid RO4350B with dielectric constant of 4.6 and 3.48 respectively. To realize the concept, reconfigurable SIW filter and reconfigurable patch antenna have been combined using the multilayer technique into a single structure while UWB antenna and reconfigurable notch filter were combined on the same planar. To validate the design technique, the equivalent circuit model of the tunable varactor diode network is presented to study the tunability mechanism. Two commercial software programs that have been used in the design and development of two main designs namely Advanced Design System (ADS) software and CST Studio Suite software. All designs were simulated, manufactured and measured. Reconfigurable integrated SIW filter and antenna provide a good attenuation tuning range about 15.5 dB with improvement up to 55 % and only shifts 1 MHz from the origin centre frequency while reconfigurable UWB antenna with band-notched provide a good range up to 210 MHz. This design has smaller compact size of 37.6 mm x 28.0 mm with bandwidth for peak notch of 224.76 MHz and 89.90 MHz for both notches. The experimental results show a good agreement with the simulated results. The benefits of the reconfigurable integrated design are potentially miniaturizing overall structure, good tuning capability, easy to fabricate and cost effective. The outcomes of the proposed reconfigurable integrated design may facilitate improvements in an integrated technique with a good tuning capability for wireless communication systems

UWB Technology

Ultra Wide Band (UWB) technology has attracted increasing interest and there is a growing demand for UWB for several applications and scenarios. The unlicensed use of the UWB spectrum has been regulated by the Federal Communications Commission (FCC) since the early 2000s. The main concern in designing UWB circuits is to consider the assigned bandwidth and the low power permitted for transmission. This makes UWB circuit design a challenging mission in today's community. Various circuit designs and system implementations are published in this book to give the reader a glimpse of the state-of-the-art examples in this field. The book starts at the circuit level design of major UWB elements such as filters, antennas, and amplifiers; and ends with the complete system implementation using such modules

A Compact Reconfigurable Dual Band-Notched Ultra-Wideband Antenna using Varactor Diodes

In this paper, a reconfigurable dual band-notched ultra-wideband (UWB) antenna is presented. The antenna design consists of a circular shape with two pairs of the L-resonator. To realize the notch characteristics in WLAN at 5.2 GHz and 5.8 GHz bands, the half wavelength of the L-resonator is introduced in the design. The T-shaped notch is etched in the ground to enhance the bandwidth which covers the UWB operating frequency range from 3.219 – 10.863 GHz. The proposed reconfigurable dual band-notched UWB antenna shows good impedance matching for the simulated in the physical layout. Furthermore, the proposed antenna has a compact size of 37.6 x 28 mm2. This proposed reconfigurable design can provide an alternative solution for the wireless system in the designing of a band-notched antenna with a good tuning capability

A planar UWB semicircular-shaped monopole antenna with quadruple band notch for WiMAX, ARN, WLAN, and X-Band

This paper proposed quadruple notched frequency bands ultra-wideband (UWB) antenna. The antenna is a semicircular-shaped monopole type of a compact size 36x24 mm, covering frequency range of 3.02-14 GHz. Four rejected narrow bands including WiMAX (3.3-3.7GHz), ARN (4.2-4.5 GHz), WLAN (5.15-5.825GHz), X-Band (7.25-7.75) have been achieved using inserting slots techniques in the patch, feed line, and ground plane. The slots dimensions have been optimized for the required reject bands. The antenna design and analysis have been investigated by simulation study using CST-EM software package. The antenna characteristics including impedance bandwidth, surface current, gain, radiation efficiency, radiation pattern have been discussed

Tunable n-path notch filters for blocker suppression: modeling and verification

N-path switched-RC circuits can realize filters with very high linearity and compression point while they are tunable by a clock frequency. In this paper, both differential and single-ended N-path notch filters are modeled and analyzed. Closed-form equations provide design equations for the main filtering characteristics and nonidealities such as: harmonic mixing, switch resistance, mismatch and phase imbalance, clock rise and fall times, noise, and insertion loss. Both an eight-path single-ended and differential notch filter are implemented in 65-nm CMOS technology. The notch center frequency, which is determined by the switching frequency, is tunable from 0.1 to 1.2 GHz. In a 50- environment, the N-path filters provide power matching in the passband with an insertion loss of 1.4–2.8 dB. The rejection at the notch frequency is 21–24 dB,P1 db> + 2 dBm, and IIP3 > + 17 dBm

Ultra-wideband bandpass filter with notch band based on quadratic Koch Island structure

An ultra-wideband bandpass filter with a notch band centered at 7.2 GHz is proposed to remove the interference caused by satellite communication signal coexciting within the ultra wide band. The filter comprises of two seperated quadratic koch island structures connected to the main transmission line to generate the notch band at the desired frequency. The designed ultra wide bandpass filter passes frequencies from 3.09 GHz to 10.61 GHz with a notch band from 7.12 to 7.46 GHz centered at 7.2 GHz and with a rejection level of 21.3 dB.The resonant frequency and bandwidth of the notch can be varied by the variation in the physical parameter of the filter. The proposed filter is fabricated, tested and compared with simulated results