Reconfigurable Antennas for UWB Cognitive Radio Communication Applications

In this chapter, reconfigurable antennas are reviewed for ultra-wideband (UWB) cognitive radio communication applications. The defected microstrip structure (DMS) has been reviewed and integrated into the UWB antennas to form the desired filtering antennas which can filter out unexpected narrowband signal interferences. Then, switches are incorporated into the filtering UWB antennas to construct the cognitive radio UWB (CR-UWB) antenna to make the antenna switch between the UWB antenna and band-notched UWB antenna. In these CR-UWB antennas, the DMSs are to give the desired notches while the switches are used for realizing the switchable characteristics. Several reconfigurable antennas and CR-UWB antennas are created and investigated. The results show that the designed CR-UWB antenna can switch between different modes, making it amazing for UWB, band-notched UWB, and multiband communication system applications

A novel compact fractal UWB antenna with triple reconfigurable notch reject bands applications

A compact, circular UWB fractal antenna with triple reconfigurable notch rejection bands is proposed. It rejects the crowded frequency bands WiMAX, WLAN and X band interferences produced in UWB communication systems. The proposed fractal structure consists of a basic circular patch with circular fractal iterations. By employing this new structure of fractals, the overall size of antenna is reduced 53% to 21 × 25 mm, in comparison with traditional circular monopole antenna. The implemented antenna operates at 3.1–10 GHz. Re-configurability is realized by designing slots and split ring resonators in desired frequencies with the attached PIN diodes. WLAN band rejection was realized by creating a pair of optimized L-shaped slots in the ground plane. By etching a split ring resonator and a U-shaped slot, X and WiMAX bands were also rejected. Furthermore, by attaching diodes to aforementioned slots and designating the diodes on/off, different bands can be included or rejected. In time domain, the antenna properties are evaluated by a figure of merit called fidelity factor. Finally, the antenna properties are measured in anechoic chamber and the results agrees with simulation findings

A reconfigurable dual port antenna system for underlay/interweave cognitive radio

An antenna system that is reconfigurable in frequency is presented in this paper as a novel dual port design that serves both undelay and interweave cognitive radio. This 25×40×0.8 mm3 system is composed of two wide slot antennas: the first is designed as an ultra-wideband (UWB) antenna with controllable band rejection capabilities, while the second antenna is reconfigurable for communication purposes. Three slots are etched into the patch of the UWB antenna to obtain band notching in wireless local area network/Xband/International Telecommunication Union bands (WLAN/Xband/ITU) bands which can be controlled by a positive-intrinsic-negative (PIN) diode across each slot. The configuration states of these three diodes are all useable that produces seven band rejection modes plus the UWB operation mode. The second antenna is configured by five PIN diodes to operate either in Cband, WLAN or Xband regions which results in three interweave modes when setting the first antenna for UWB sensing. The design is simulated by computer simulation technology (CST) v.10. S21 results shows good isolation while input reflection coefficient and realized gain results prove system’s scanning, filtering and communication capabilities. This system is new that it gathers the undelay/interweave operation in a single design and when considering its large number of operation modes it looks adequate for many cognitive radio applications

Design a new notched UWB antenna to rejected unwonted band for wireless communication

This paper presents a slotted design for ultra-wideband (UWB) antenna. Design of a rectangular UWB antenna covering the frequency range 3.1-10.6 GHz, to achieve notch characteristics in the bands at 3.1-8.4 GHz and 8.6-10.6 GHz. By changing the direction of distribution of current to apply this technique by inserting three C-shaped holes and two pairs of rectangular notches below the antenna. The simulation results reveal that the proposed structure is in good accord with the simulation results. The proposed UWB antenna size is (100x90x1.6 mm)3. This proposed design could provide a solution to eliminating bands that interfere in a UWB band depending on the aperture design. The simulated findings reveal that the UWB antenna operates in the 8.5 GHz center frequency range and rejects all frequency bands utilizing slits. This antenna design can provide a solution to remove UWB bands from 3.1-10.6 except for 8.5 GHz which only works. By using the notch, we got a large increase in the gain. makes to be a suitable candidate for X-band-UWB applications

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

Compact Planar Ultrawideband Antennas with Continuously Tunable, Independent Band-Notched Filters

© 2016 IEEE. A compact planar ultrawideband antenna with continuously tunable, independent band notches for cognitive radio applications is presented. The antenna is fabricated using a copper-cladded substrate. A radiating patch with an inverted rectangular T-slot is etched on the top side of the substrate. A straight rectangular strip with a complete gap is embedded into the T-slot. By placing a single varactor diode across this gap, a frequency-agile band-notch function below 5 GHz is realized. On the bottom side of the substrate, a U-shaped parasitic element having an interdigitated-structure is placed beneath the radiating patch. The second narrow band notch is created by inserting a second varactor diode into the gap on one leg of the parasitic element. It has a frequency-agile performance above 5 GHz. The presence of the interdigitated structure suppresses higher order resonant modes and enhances the tunability of the notched bandwidth. Because these antenna structures naturally block dc, a very small number of lumped elements are required. The experimental results, which are in good agreement with their simulated values, demonstrate that both band notches can be independently controlled and the entire frequency-agile fractional bandwidth is as high as 74.5%, demonstrating a very wide notched frequency-agile coverage

Analysis and design of a compact ultra-wideband antenna with WLAN and X-band satellite notch

A compact design of ultra-wideband (UWB) antenna with dual band-notched characteristics based on split-ring resonators (SRR) are investigated in this paper. The wider impedance bandwidth (from 2.73 to 11.34 GHz) is obtained by using two symmetrical slits in the radiating patch and another slit in the partial ground plane. The dual band-notch rejection at WLAN and X-band downlink satellite communication system are obtained by inserting a modified U-strip on the radiating patch at 5.5 GHz and embedding a pair of rectangular SRRs on both sides of the microstrip feed line at 7.5 GHz, respectively. The proposed antenna is simulated and tested using CST MWS high frequency simulator and exhibits the advantages of compact size, simple design and each notched frequency band can be controlled independently by using the SRR geometrical parameters. Therefore, the parametric study is carried out to understand the mutual coupling between the dual band-notched elements. To validate simulation results of our design, a prototype is fabricated and good agreement is achieved between measurement and simulation. Furthermore, a radiation patterns, satisfactory gain, current distribution and VSWR result at the notched frequencies make the proposed antenna a suitable candidate for practical UWB applications

Band-Notched UWB Antenna with Switchable and Tunable Performance

A band-notched UWB antenna is presented, which can switch between two notch bands and tune the central frequency simultaneously. It is the first time that the switchable and tunable behaviours are combined together in band-notched UWB antennas. In the band-notched structure, PIN diodes are used to switch the lower and upper frequency bands, while varactors could vary the central frequency of each notch band continuously. Measurement results show that the notch bands could switch between 4.2 GHz and 5.8 GHz when the state of varactors is fixed, and the ranges of tuning are 4.2–4.8 GHz and 5.8–6.5 GHz when the state of PIN diodes is ON and OFF, respectively

Slotted Printed Monopole UWB Antennas with Tuneable Rejection Bands for WLAN/WiMAX and X-Band Coexistence

YesFour versions of the compact hexagonal-shaped monopole printed antennas for UWB applications are presented. The first proposed antenna has an impedance bandwidth of 127.48 % (3.1 GHz to 14 GHz), which satisfies the bandwidth for ultra-wideband communication systems. To reduce the foreseen co-channel interference with WLAN (5.2GHz) and X-Band systems (10GHz), the second and third antennas type were generated by embedding hexagonal slot on the top of the radiating patch. The integration of the half and full hexagonal slots created notched bands that potentially filtered out the sources of interference, but were static in nature. Therefore, a fourth antenna type with tuneable-notched bands was designed by adding a varactor diode at an appropriate location within the slot. The fourth antenna type is a dual-notch that was electronically and simultaneously tuned from 3.2GHz to 5.1GHz and from 7.25GHz up to 9.9GHz by varying the bias voltages across the varactor. The prototypes of the four antenna versions were successfully fabricated and tested. The measured results have good agreement with the simulated results.This work is carried out under the grant of the Fundacão para a Ciência e a Tecnologia (FCT - Portugal), with the reference number: SFRH / BPD / 95110 / 201

Compact UWB Monopole Antenna with Tunable Dual Band Notched Characteristics for WiMAX and WLAN Applications

The present work shows a planar compact ultra-wideband (UWB) monopole antenna with controllable dualband-notch frequencies at 3.3 GHz for WiMAX and 5 GHz for WLAN. In the proposed antenna, the lower notchband (at a frequency of 3.3 GHz) is made by cutting a thin horizontal strip on top of the radiating patch. The uppernotch band (at a frequency of 5 GHz) is made by putting two narrow parasitic strips in the shape of an “I” oneither side of the radiating patch. The incorporation of three varactor diodes between the radiating patch and three metallic strips provides the flexibility of adjusting the notch frequencies. The notch band tunability between 3.15 GHz and 3.69 GHz and between 4.93 GHz and 5.59 GHz, respectively, is achieved by changing the bias voltageof the varactor diode between 0 V and 30 V. The gain and efficiency characteristics of the designed antenna alsoexhibit band rejection at the respective notch frequencies. The design principle is validated by fabricating andmeasuring a prototype of the proposed dual-band, notched UWB antenna. For three different bias voltages of thevaractor, the simulated and experimental findings are in reasonable agreement. The proposed works demonstratebetter-notch characteristics as compared with other reported works over the UWB rang