Band Notch Research Articles

Design of Ultra-Wideband Bandpass Filters With Fixed and Reconfigurable Notch Bands Using Terminated Cross-Shaped Resonators

In this paper, a novel terminated cross-shaped resonator (TCSR) is analyzed and used to design ultra-wideband (UWB) bandpass filters (BPFs) with fixed and reconfigurable notch bands. It is found that the TCSR can exhibit a maximum three poles and two zeros when open and short terminations are applied. The intrinsic zero is simply used for the implementation of notch bands offering systematic design and flexible tuning capabilities. Bandwidth can also be kept unchanged when tuning a notch within the UWB passband. In contrast to common band-notched UWB BPFs using additional notch resonators, only a single TCSR is required to realize band-notched UWB filters. Three UWB BPF prototypes, including a four-pole filter with 94.7% fractional bandwidth (FBW) and a notch band at 5.8 GHz, a five-pole filter with 111% FBW and dual notch bands at 4.3/9.1 GHz, and a four-pole filter with 82.4% FBW and reconfigurable notch band from 4.6 to 6.5 GHz are designed and experimentally characterized. Their experimental characterizations are in good agreement with theoretical analysis validating a simple approach of band-notched UWB BPF design.

Novel Dual-band Slot Antenna Design for Bluetooth and UWB Applications

A novel technique to introduce an additional low frequency band to compact ultra wideband (UWB) slot antennas is proposed in this paper. To get an additional Bluetooth band, a parasitic strip is mounted on the back side of the slot edge. Because of the interaction of the strip and the slot edge, the Bluetooth band can be obtained while a notch band between the Bluetooth band and UWB band also appears. Two types of feeding, coplanar waveguide and microstrip line, are investigated. The proposed antennas are both fabricated on a low-cost FR4 substrate and have compact size (24 mm × 28 mm × 1 mm). The good agreement between measured and simulated results verifies our design.

Ultrawideband notch‐band power divider with bandpass response using defect microstrip structure

AbstractA novel ultrawideband (UWB) notch‐band power divider with bandpass response has been presented. The short‐circuited coupled lines and open/short‐circuited slotline are introduced to construct this power divider. A resistor, R, is located across the slotline to improve the isolation between the output ports. The defected microstrip structure has been embedded to the UWB power divider and the notch band within the UWB passband is implemented. The central frequency and bandwidth of the notch band can be controlled by tuning the structural parameters. The presented power divider has been developed and measured. The measured notch band is located at 5.9 GHz with an attenuation of around 22 dB. The measured results show reasonable agreement with the predicted ones. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:711–715, 2014

Implementation and justification of a triple frequency‐notched UWB proximity‐fed antenna with shunt stubs

ABSTRACTIn this article, an ultrawideband (UWB) antenna with triple band‐rejection characteristics is proposed. The antenna is compact with size of 22.5 × 24 mm2. Matching between a sector‐disk shaped radiating patch and the 50‐Ω microstrip line is manipulated through a proximity‐feed technique. An elliptically‐shaped aperture is etched in the ground plane to enhance the antenna bandwidth. Double shunt stubs are used to get more enhancement of the impedance bandwidth of the antenna. The band notches at WiMAX of 3.3–3.9 GHz, lower WLAN of 5.15–5.35 GHz, and upper WLAN of 5.725–5.825 GHz are realized by embedding three elements; a reversed F‐shaped slot etched off in the patch, a reversed U‐shaped slot etched off in the feed line, and adding a parasitic flipped C‐shaped strip around the patch, respectively. The antenna is fabricated and the experimental data show that the designed antenna has an impedance bandwidth of 3.2–11.6 GHz for VSWR less than 2, except at three frequency stop‐bands of 3.20–4.19, 5.02–5.32, and 5.51–6.10 GHz. Curve fitting formulations to describe the influences of the embedded structures on the corresponding notched frequencies are obtained by using a second‐order polynomial. Moreover, physical lumped elements of an electrical equivalent circuit model of the proposed antenna are obtained using a rational function approximation based on the vector fitting technique. The antenna provides almost omnidirectional patterns, relatively flat gain, and high radiation efficiency over the entire UWB frequency excluding the rejected bands. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:646–654, 2014

Design and realization of a planar ultrawideband antenna with notch band at 3.5 GHz.

A small antenna with single notch band at 3.5 GHz is designed for ultrawideband (UWB) communication applications. The fabricated antenna comprises a radiating monopole element and a perfectly conducting ground plane with a wide slot. To achieve a notch band at 3.5 GHz, a parasitic element has been inserted in the same plane of the substrate along with the radiating patch. Experimental results shows that, by properly adjusting the position of the parasitic element, the designed antenna can achieve an ultrawide operating band of 3.04 to 11 GHz with a notched band operating at 3.31–3.84 GHz. Moreover, the proposed antenna achieved a good gain except at the notched band and exhibits symmetric radiation patterns throughout the operating band. The prototype of the proposed antenna possesses a very compact size and uses simple structures to attain the stop band characteristic with an aim to lessen the interference between UWB and worldwide interoperability for microwave access (WiMAX) band.

Two-Step Beveled UWB Printed Monopole Antenna with Band Notch

This paper presents a novel compact printed monopole ultra-wideband (UWB) antenna featured with the band notch. The proposed antenna consists of a two-step beveled radiant patch and a truncated ground plane, which can provide a good impedance matching from 3.1 GHz to 10.6 GHz. In order to generate the band-notched characteristics, two symmetrical slots are embedded along with the microstrip feeding line, resulting in a band notch from 5.05 GHz to 5.85 GHz. Accordingly, the mutual electromagnetic interference between the UWB and wireless local area network (WLAN) radio communication systems can be eliminated. In addition, it is shown how the slots integrated on the ground plane improve the radiation patterns. The experimental measurements are found to be in good agreement with the numerical simulations.

PLANAR ULTRAWIDEBAND MONOPOLE ANTENNA WITH TRI-NOTCH BAND CHARACTERISTICS

In this article, a compact ultra-wideband (UWB) planar monopole antenna with the triple notched band is proposed. The antenna consists of a semicircular radiating patch and a modifled ground plane with two bevels at upper edge. By etching two round shape slots in radiating patch the notch characteristics are achieved at WiMax band (3.3{3.7GHz) and WLAN band (5.15{5.875GHz). In order to realize notch band at X-band downlink satellite communication band (7.1{7.76GHz) a pair of rotated V-shape slot are etched on the ground plane. The measured operating impedance bandwidth of proposed antenna ranges from 2.9 to 10.9GHz having return loss less than 10dB with triple notched bands. The proposed antenna exhibits a nearly omnidirectional radiation pattern in the H-plane, and a dipole-like radiation pattern in the E-plane for the ultra-wideband. The efiects of each individual slot on band-notch characteristics are also investigated. The measured gain of the proposed triple band notched antenna is relatively stable across the operating frequency band except notched bands and thereby making the proposed antenna suitable for practical UWB applications. Proposed antenna has a compact size of 27 £ 25mm 2 .

DESIGN OF DUAL BAND NOTCH UWB MONOPOLE ANTENNA USING DUAL-ARM SPIRAL RESONATOR

An ultra wideband (UWB) monopole antenna with dual band-notch characteristic is proposed. Dual arm spiral resonators (DASR) are placed on both sides of the feed line to create band notches at 5.25 and 5.8GHz for the upper and lower WLAN bands respectively. First the antenna is optimized individually for both upper and lower WLAN band-notch behaviors then embedded together for dual band-notch characteristic. The measured results ensure that two band notches are achieved, and the antenna can be used for UWB applications without any interference from WLAN band.

BAND-NOTCHED UWB MONOPOLE ANTENNA DESIGN WITH NOVEL FEED FOR TAPER RECTANGULAR RADIATING PATCH

In this paper, a novel dual notch bands Ultra Wide-Band (UWB) antenna for WLAN and WiMAX applications is presented. The antenna contains a taper rectangular monopole antenna with new feed line which is designed and modifled for 2{12GHz. To achieve notch band at WLAN frequencies, difierent methods are compared such as L-shape slots for one notch or dual rings in notch designing. On the other hand, the novel F-shape feed line is designed to achieve dual notch band characteristic. The efiects of stubs parameters at notch frequencies are presented. The beneflt of this novel feed line is designing multi-band and reconflgurable antenna by changing stub line parameters. The simulated results of prototype antenna are obtained with HFSS and CST. Total size of the antenna is 60mm£60mm£1:6mm. It is fabricated on FR-4 low cost substrate and fed by 50› microstrip line.

Single-Layer Differential CPW-Fed Notch-Band Tapered-Slot UWB Antenna

A single-layer differential coplanar waveguide (CPW)-fed notch-band tapered-slot ultrawideband (UWB) antenna is proposed in this letter. In order to achieve the sharp and controllable notch-band characteristic, one pair of half-wavelength stubs and slits are introduced inside the tapered slot and in the circular patches, respectively. Compared to a single-ended CPW-fed UWB antenna, due to adopting the differential feeding structure, the proposed antenna has lower cross polarization. Since all of the structures are printed on the same layer of the substrate, it can be fabricated easily and very suitable to be integrated with RF front-end circuits. The measured -10-dB impedance bandwidth is 126% (from 2.78 to 12.3 GHz), along with a sharp notch band from 5.2 to 6.0 GHz. Good agreement is achieved between the measured results and simulated results.

DUAL BAND NOTCHED UWB MONOPOLE ANTENNA USING EMBEDDED OMEGA SLOT AND FRACTAL SHAPED GROUND PLANE

This paper presents the development of an Ultra Wide Band (UWB) monopole antenna with dual band notch characteristics. Modifled crown-square shaped fractal slots in the ground-plane are implemented to enhance the impedance bandwidth to around 58% as compared to conventional square monopole antenna without slots. Impedance bandwidth of the proposed antenna is approximately 114% with Voltage standing wave ratio (VSWR) < 2. In addition to this, two omega-shaped (›) slots have been incorporated in the radiating patch to render band-notch characteristics centered at 5.5GHz band assigned to IEEE802.11a and HIPERLAN/2 as well as X-band for satellite communication centered at 7.5GHz band. Measured antenna gain is stable over the entire UWB region except at the notch bands. Radiation pattern of the antenna show that the proposed antenna exhibits nearly monopole like E plane radiation patterns and omni-directional H plane radiation patterns throughout the band. A fabricated prototype is developed with close agreement between simulated and measured results.

A Flexible Monopole Antenna with Dual-Notched Band Function for Ultrawideband Applications

We present a flexible ultrawideband (UWB) planar monopole antenna with dual-notched band characteristic printed on a polyimide substrate. The antenna is fed by a step coplanar waveguide (CPW) that provides smooth transitional impedance for improved matching. It operates from 2.76 to 10.6 GHz with return loss greater than 10 dB except for the notch band to reduce the interference with existing 3.5 GHz WiMAX band and 5.5 GHz WLAN band. With a combination of rectangular and circle patches in which the U-shaped slot is carved, the overall size of antenna is 30 mm × 20 mm. Moreover, a pair of arc-shaped stubs located at both sides of the feed line is utilized to create the notch band for WiMAX band. The results also show that the antenna has omnidirectional radiation pattern and smooth gain over the entire operational band.

Design of a Compact UWB Antenna with Triple Band-Notched Characteristics

A new compact ultra-wideband (UWB) antenna with triband-notched characteristics is presented. The structure of the proposed antenna is simple and symmetric. A modified ground is introduced to obtain a wide impedance bandwidth of 2.9–13.4 GHz withS11&lt;-10 dB. By inserting two arc-shaped slots in the radiation patch, two sharp bands of 3.3–3.7 GHz and 5.15–5.35 GHz are notched. The notch band of 7.25–7.75 GHz is achieved by etching a U-shaped slot in the ground plane. The notched bands can be controlled, respectively, while the characteristics of the proposed UWB antenna almost keep completely unchanged at the unnotched frequencies. Equivalent circuit models, surface current distributions, and input impedance are applied to analyze the principle of the proposed UWB antenna. Parametric studies are given. Simulated and measured results show that the proposed antenna has good impedance matching, stable radiation patterns, and constant gain.

A Compact Microstrip-Fed Triple Band-Notched UWB Monopole Antenna

In this letter, a novel low-profile microstrip-fed compact triple band-notched ultrawideband (UWB) antenna is proposed. Notch bands around the 3.3-3.8-GHz WiMAX and 5.15-5.85-GHz WLAN frequencies are obtained by etching out two elliptic single complementary split-ring resonators (ESCSRRs) of different dimensions from the radiating patch of the antenna. Furthermore, by placing two rectangular split-ring resonators near the feedline-patch junction of the antenna, rejection for the 7.9-8.4-GHz X-band frequencies is achieved. Design guidelines for implementing the notch-bands at the desired frequency regions are provided. The match between the simulated and experimental results suggests that the proposed antenna can be a good candidate for application in UWB communication systems.

A GENERALIZED CONCEPT FOR BAND NOTCH GENERATION IN ULTRA-WIDE BAND ANTENNAS

In this paper a generalized concept to generate two band notches by adding parasitic elements having predictable positions to a wide slot ultra-wide band (UWB) antenna is proposed. The elimination of the wireless local area network (5.15-5.825 GHz) is achieved by a pair of radiating parasitic elements. Each element operates as a quarter wavelength resonator. A pair of half wavelength resonators in a form of a pair of parasitic strips is engraved in the ground plane side of the substrate directly behind the antenna tuning stub to break the coupling between the feed line and the slot, which represents the basic operation concept of the wide slot antenna, at the X-band satellite communications down link (7.25-7.745 GHz). Analysis shows that the proposed mechanisms are suitable for all wide slot antennas. The simulation and measured parameters are in good agreement, and results also show that the antenna has high voltage standing wave ratio and low gain inside the eliminated bands, while outside the notched bands it has a bandwidth that covers the entire UWB band and has very stable radiation characteristics.

ANALYSIS OF CPW-FED UWB ANTENNA FOR WIMAX AND WLAN BAND REJECTION

A compact ultra wide band (UWB) antenna with dual band notch characteristics is proposed. The antenna consists of a coplanar waveguide (CPW) fed bevelled rectangular patch and a modifled rectangular ground plane. A Z-shaped meander line parasitic element and a pair of symmetrical L-shaped quarter-wavelength stubs are employed to realise band-notched functions at WiMAX and WLAN bands respectively. By optimizing the dimensions and positions of these notch structures, the desired notch-bands of WLAN and WiMAX are achieved. Unlike other dual band-notched antennas reported in literature this antenna has a merit of regulating the centre frequency as well as the bandwidth of both the notched bands easily and independently. The measured i10dB S11 covers the bandwidth from 2.5 to 11.5GHz, with two notched bands from 3.3 to 3.6GHz and 5.2 to 5.75GHz. The proposed antenna exhibits nearly omni-directional radiation patterns with moderate gain and small group delay variations less than 0.5ns over the entire operating bandwidth except at the notched bands. Moreover, by using antenna transfer function, the time domain characteristic of the antenna is also studied to conflrm its suitability for UWB pulse communication.

Wideband Monopole Antenna With Three Band-Notched Characteristics

A configuration of multiband and compact ultrawideband (UWB) antenna is present. The antenna is printed on a dielectric substrate and fed by microstrip line. The dimensions of square slots etched into the microstrip feedline can be used to tune the antennas' band-notch and bandwidth characteristics. This antenna is designed to cover the bandwidth for UWB applications (3.1-10.6 GHz) with a VSWR lower than 2 and provide sufficient rejection band notches for WiMAX (3.3-3.88 GHz), WLAN (4.96-6.23 GHz), and ITU (7.9-8.7 GHz). A better gain pattern is realized by inserting slots in the microstrip feedline, compared to the defected structure. Furthermore, by the analysis of the current distribution on the antenna surface, we can deduce the equivalent circuit of the antenna.

Packaged Tunable Notch Filters

One of the student design competitions on packaged tunable notch filter design was held during the 2013 IEEE Microwave Theory and Technique Society (MTT-S) International Microwave Symposium (IMS2013) in Seattle. This article describes the winning work at the student competition. According to the competition design rules, the tunable notch filter structure must be planar. The lumped surface-mounted components, including resistors, capacitors, and varactors, are allowed and must be tightly mounted on the printed circuit board. The printed circuit board will be mounted in a metal package, and it must be securely sealed with a copper tape lid. The metal package was placed on another unenclosed printed circuit board with the 50-X traces, connecting the radio-frequency (RF) port of the package to the standard 50-X female subminiature version A (SMA) connector. The varactor diode and the metal package are provided by the competition committee. The filter performance was evaluated based on the measurement performance between the SMA connectors. In this competition, it provided the S-parameter measurement with a voltage range between 0 and 20 V to realize two bands of the tunable notch filter. The first band specifications are (1) the notch band frequency: 685-730 MHz (2) in-band insertion loss: > 20 dB (3) out-of- band (f f2 ) insertion loss: <; 4 dB.

CLOSELY SPACED DUAL BAND-NOTCHED UWB ANTENNA FOR MIMO APPLICATIONS

A closely spaced dual-band notched UWB MIMO antenna is proposed in this paper. A traditional semi-circular monopole with ultra-wideband operation is chosen as an element of the proposed MIMO antenna. When two of the UWB monopoles are put together closely, the mutual coupling between them is apparently strong. To reduce the coupling between the antenna elements, a T-shaped branch is inserted between them, which reduces the mutual coupling obviously over the entire operating band. Also, the T-shaped branch can perform as a compensating radiator which can lower the operating frequencies of the proposed antenna. In order to achieve dual band-notched characteristics, meandering slots are cut in the patches, and symmetrical C-shape strips are nearly placed to the monopoles' feed-lines. The meandering slot is for lower band notch (WiMAX, 3.3{3.7GHz) while the C-shape strips are for upper band (WLAN, 5.15{5.825GHz). The measured radiation e-ciencies, peak gains and radiation patterns are illustrated and show good agreement as anticipated.

Cognitive Radio Transceivers: RF, Spectrum Sensing, and Learning Algorithms Review

A cognitive transceiver is required to opportunistically use vacant spectrum resources licensed to primary users. Thus, it relies on a complete adaptive behavior composed of: reconfigurable radio frequency (RF) parts, enhanced spectrum sensing algorithms, and sophisticated machine learning techniques. In this paper, we present a review of the recent advances in CR transceivers hardware design and algorithms. For the RF part, three types of antennas are presented: UWB antennas, frequency-reconfigurable/tunable antennas, and UWB antennas with reconfigurable band notches. The main challenges faced by the design of the other RF blocks are also discussed. Sophisticated spectrum sensing algorithms that overcome main sensing challenges such as model uncertainty, hardware impairments, and wideband sensing are highlighted. The cognitive engine features are discussed. Moreover, we study unsupervised classification algorithms and a reinforcement learning (RL) algorithm that has been proposed to perform decision-making in CR networks.