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Multiple standard communication networks operate in the frequency band of 1.8–6 GHz, which makes lots of antennas available in the limited space. To solve the problem of interference and improve the performance of these antennas, an ultra-wideband (UWB) antenna is presented. It consists of a boat-radiator and a dual C-shape co-radiative ground (DCCRG). One half of the DCCRG plays a role of the ground of a co-planar waveguide fed to the proposed boat-radiator antenna (BRA), while the other half works as a multiple order L-resonant circuit to broaden the lower operating band. Uniform bidirectional radiation is presented with the size of 0.25 λ × 0.375 λ × 0.0063 λ over the frequency band of 1.7–6.3 GHz (115%). The proposed antenna achieves around twice the bandwidth (60%) of the same structured antenna without the structure acting as a multiple order L-resonant circuit. Moreover, the stable boresight gain of 3.6 dBi ± 1.25 dBi is realized over the operating band.

A dual slant polarized slot antenna is proposed. The antenna is printed on the two sides of a single substrate and has two microstrip feed lines to excite a V-shaped slot formed by the merging of two tilted rectangular step shaped slots. Stepping of the slot sections as well as the feed line improves the impedance matching. A narrow rectangular metallic stub is introduced at the junction of the slot arms to improve the decoupling between the ports. The antenna polarization is +450/−450 with respect to horizontal under alternate excitation and this dual slant polarized nature is demonstrated through aperture electric field plots and far field radiation patterns. The measured return loss bandwidth (S11

This paper presents an ultra-wideband (UWB) micro-strip patch antenna design for microwave breast phantom imaging system. By optimizing the shape of radiating elements, the antenna achieves UWB characteristics with excellent frequency ratio. The antenna was fabricated and tested in both time and frequency domain analysis. Sufficient agreement between the simulated and measured data was observed. The antenna achieves a wider bandwidth of 8.2 GHz (2.5 GHz to 11.2 GHz) with good gain and radiation pattern. The antenna has optimum design comparing to the theoretical Qfactor and the near field directivity (NFD) is also observed. Effective near-field microwave breast phantom measurement systems with an array of 9 UWB antennas is proposed and the performance is tested with and without tumor cells inside the breast phantom. The backward scattered signals analysis shows that the presence of tumor with higher dielectric constant than normal cells. Thus, the proposed antenna can be a good candidate for microwave breast tumor detection. [ABSTRACT FROM AUTHOR]

A compact (27.5 × 16.5 × 0.8 mm³) co-planar waveguide fed printed ultra-wideband antenna operating in the impedance band of 1.75-10.3 GHz with two wide frequency notch bands at 2.2-3.9 GHz and 5.1-6 GHz, is introduced. Dual notch is achieved by inserting U-slot on the radiator and with inverted patch shaped downscaled parasitic load at the opposite end of feed line. Maximum antenna gain augmentation by about 5 dBi is achieved without changing the bandwidth, by incorporating a dual layer reflective frequency selective surface (FSS) of dimension 33 × 33 × 1.6 mm³ below the antenna. The antenna- FSS composite structure exhibits maximum radiation in the broadside direction with a peak gain of 9 dBi and an average radiation efficiency of more than 80% in the operating band. Antenna transfer function and group delay are experimentally studied in ground coupling mode of ground penetrating radar (GPR). Linear magnitude response of transfer function and consistent, flat group delay are achieved, that ensure minimal antenna dispersion and its ability for GPR application. [ABSTRACT FROM AUTHOR]

In this paper, a compact superformula ultra‐wideband (UWB) monopole antenna with dual band notches is proposed. The developed structure achieves UWB performance as well as a compact size of 20 × 26 × 1.62 mm3. Furthermore, to avoid interferences with WiMAX and satellite communication systems, dual notched band is obtained by engraving two co‐directional triangular split ring defects on the radiating element. The simulated and measured results show that the proposed antenna has an impedance bandwidth extending from 3.05 to 20 GHz with dual notched bands at [5.15‐5.68 GHz], and [7.15‐7.65 GHz] used in WiMAX and satellite communication, respectively. The proposed design realizes omnidirectional radiation pattern in H‐plane, and a dipole‐like pattern in E‐plane. The antenna exhibits an acceptable gain in the whole UWB range except at notched bands. [ABSTRACT FROM AUTHOR]

In this paper, a compact ultra-wideband (UWB) monopole antenna with triple band-notched characteristics is presented. These triple band rejections are produced by inserting the Complementary Co-directional Split-Ring Resonator (CC.SRR) on the radiating element for WiMAX/WLAN (3.4–3.95 GHz/5.35–5.9 GHz) and Electromagnetic Band Gap (EBG) structure in the vicinity of transmission line for X-band satellite communications (6.7–7.7 GHz). The proposed antenna with a total size of 18×20.9×1.63 mm3 has been constructed and tested. An equivalent RLC circuit model is proposed and investigated. The simulated and measured results show that the proposed antenna has an impedance bandwidth (VSWR<2) extanding from 3.05 GHz to 14 GHz with triple notched bands of [3.3–3.9 GHz], [5.25–5.86 GHz] and [6.7–7.7 GHz]. The triple band notched characteristics and the good radiation patterns make the proposed antenna a good candidate for the UWB applications. [ABSTRACT FROM AUTHOR]

This article presents a compact four-element MIMO antenna for WLAN/LTE/UWB applications. The half-slot structure and half-cut monopole antenna technique are adopted to realize bandwidth from 2 GHz to 10.6 GHz while maintaining good isolation better than 15 dB and compact size of 31 × 31 × 1.6 mm. Each antenna element is composed of a quasi-semi-ellipse radiator and a protuberant ground. To be practical in a real application scenario, four antenna elements with interconnected/common ground are placed orthogonal to each other for good isolation. Key parameters affecting the antenna performance are investigated and a prototype of the proposed antenna is fabricated for measurement. The simulated and measured results agree well, testifying the proposed four-element MIMO antenna is a suitable candidate for WLAN/LTE/UWB applications. [ABSTRACT FROM AUTHOR]

Abstract: In this article, a novel monopole antenna for the ground penetrating radar applications is proposed. The antenna is a monopole bowtie with two slots and a defected ground plane, in order to improve the bandwidth. The proposed antenna shows a great bandwidth from 3.9 to 18 GHz which makes it to be an ultra‐wideband antenna. The overall size of the antenna is 14 × 22 × 1.6 mm3 on the FR4 substrate. Also, a prototype of the proposed antenna is fabricated. The measurement and simulation results are in good agreement. [ABSTRACT FROM AUTHOR]

Abstract: This work presents an ultra‐wideband antenna with controlled gain. The gain control of antenna is achieved by employing a Reconfigurable Frequency Selective Surface (RFSS) as superstrate which is formed by 4 × 4 array of cross dipole. The filtering characteristics of the FSS are variable and depend on the PIN diodes state. The RFSS behaves as an array of cross dipole elements with stop‐band response when all diodes are in the OFF‐state and as an array of square slots with pass‐band response when the diodes are in the ON‐state. The gain improvement depends on the PIN diodes biasing. Simulation and measurements of return loss and antenna gain are presented, demonstrating changes and improvement in the antenna gain. [ABSTRACT FROM AUTHOR]

Abstract: This article presents the experimental study of a ultra‐wideband (UWB) active antenna comprising of a chaotic oscillator coupled to a dielectric resonator antenna. Wideband spectrum properties of chaotic signals are used to design an UWB active antenna. In contrast to classical active UWB antenna designed using patch, the proposed active antenna is capable of enhancing the bandwidth, easy to integrate with the oscillator and is small in size. The proposed UWB antenna using DR can be employed in UWB wireless communication systems. [ABSTRACT FROM AUTHOR]

In this paper a novel band notch antenna in UWB frequency range is designed using split rings. Split rings are overlapped with designed monopole to give phi shape. The slit gap gives band-notch operation from 5.1GHz to 6.29GHz and from 4.94GHz to 5.91GHz for SPSSR and SPSCR antennas respectively. Simulated and measured results are in good agreement. [ABSTRACT FROM AUTHOR]

In this paper, the design and test of different microwave antennas and sensors for breast cancer detection are presented. The sensors are designed and optimized to be used in direct skin contact, and for this purpose a specific breast phantom model is proposed. First, a miniaturized microstrip back-cavity Hilbert fractal antenna, operating in the ISM band (2.4-2.5 GHz), was designed. Then, this antenna was used to investigate the possibility of detecting the presence of breast tumors based on a narrowband frequency method that monitors the shift of the antenna frequency response. The antenna prototype was fabricated and tested in real in vivo measurement conditions on two different patients diagnosed with breast cancer. Measurement results have led after a comparison with the retro-simulation results of the structure to a more realistic breast model and to draw the limitations of this narrowband frequency method. As a time domain study seems to be more relevant, an UWB monopole antenna of dimensions 3 cm × 3 cm, to be used in direct contact with the breast model was designed. This antenna was optimized to both enhance the antenna/human body matching and to maximize the transfer of energy into the breast phantom by using a cavity, increasing by this way the detection potential. In order to improve the sensor’s directivity and enhance the electromagnetic field level inside the breast, a balanced antipodal Vivaldi antenna was also designed and optimized for a direct breast contact to operate in the 3.1-10.6 GHz band. A mono static and a bi static study in the time domain are finally proposed to investigate the presence of the tumor. [ABSTRACT FROM AUTHOR]

In this letter, a differential coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna with dual notched bands is presented. The proposed antenna is mainly composed of two C-shaped radiating elements and a polygon slot ground plane. To alleviate the electromagnetic signal interference, two pairs of open-ended slots etched on the ground plane are adopted to reject 3.5 GHz WiMAX band while a pair of Y-shaped slots embedded in the C-shaped radiating elements is used to filter 5.5 GHz WLAN band. Measured results demonstrate that a 10-dB impedance bandwidth implemented is 131% (from 2.57 to 12.31 GHz), along with dual notched bands of 3.29-3.95 GHz and 4.73-6.55 GHz. Furthermore, the low cross-polarization is obtained because of differential feeding structure. Finally, the antenna expresses good radiation patterns in the whole operating band. [ABSTRACT FROM AUTHOR]

In this paper, an Ultra Wide Band antenna with reconfigurable filtering-characteristic is proposed to overcome interferences problems in the frequency range 3.1 GHz- 10.7 GHz. With dimensions of 35 x 35 mm2, the structure is simple, low-cost and possesses an operating bandwidth from 3 GHz to 12 GHz. Besides, it is easy to reconfigure this antenna to filter one, two or three interferences, in which the filtering is achieved by three slots of half wavelength created in the geometry, while the reconfiguration is achieved through four PIN diodes used to control the three slot's effect. Considering the filtering action, this antenna can switch between eight distinct operational modes, which is the highest number compared to previous works. Design and analysis of the proposed configuration are done by two simulation software which are CST and HFSS. The acceptable agreement between the results obtained by both simulations proves the realistic working performance of the proposed structure. The present antenna is suitable for UWB communication applications, particularly; the which are suffering from interference issues with WiMAX 3.3 GHz-3.7 GHz, WLAN 5 GHz-5.3 GHz or ITU band 8 GHz-8.4 GHz. [ABSTRACT FROM AUTHOR]

In this paper, a fractal ultrawideband multiple-input-multiple-output antenna is proposed and its characteristics are studied in free space as well as in the proximity of on-body wireless body area network scenario. The performance of the wideband antennas are affected strongly in the proximity of the human body. Koch fractal geometry is used at the outer edges of basic octagonal geometry in the design, which helps to achieve desired miniaturization, wideband and stable radiation pattern. The presented antenna has a compact size of 25 mm × 40 mm. In addition, the effect of body tissues on antenna characteristics is analyzed by a four layered (skin, fat, muscle and bone) human tissue model. The comparative analysis of S21 is performed at a various body parts position such as abdomen, near forehead and chest with different antenna orientations. [ABSTRACT FROM AUTHOR]

Abstract: In this communication, a 4 element ultra‐wide band (UWB) multiple‐input multiple‐output (MIMO) antenna is presented. The total size of the proposed antenna is 40 × 40 mm2. A novel Sierpinski Knopp fractal geometry is used in the antenna radiator design to accomplish miniaturization. The antenna elements are placed orthogonal to each other. The spacing between any pair of elements is 0.11 λ (λ being the free space wavelength at 7.15 GHz). A CSRR shape like slot is etched on the radiating element to achieve dual band notch characteristics at WiMax 3.5 GHz and WLAN 5.4 GHz regions. The proposed antenna operates from 2.6 to 10.6 GHz, exhibiting a reflection coefficient S11 < −10 dB and an isolation better than 20 dB. The MIMO antenna does not require any additional structure to improve isolation. Envelope correlation coefficient (ECC) and capacity loss (CL) are calculated to evaluate the diversity performance of the proposed antenna. The measured values exhibit better match with the simulated results. [ABSTRACT FROM AUTHOR]

Abstract: This letter presents the design and analysis of a smart and low profile Ultra‐Wideband Slotted Planar Inverted Cone Antenna. The proposed slotted PICA has low profile (0.4 λ mm2 × 0.4 λ mm2) as compared to other existing designs and its operational bandwidth is from 3 GHz to 18 GHz. The simulated and measured results concur with acceptable return loss of better than 10 dB throughout the operational bandwidth. The radiation pattern of the antenna is omnidirectional and it has maximum Gain of 3.2 dB when placed close to human body, making it compatible for WBAN applications. [ABSTRACT FROM AUTHOR]

The development of contemporary complex technological systems prerequisites interdisciplinary design and simulation methodologies. Such an approach is demonstrated in the present work. Toward manufacturing a hand-held device aiming at internal body temperature measurements using passive microwave radiometer technology, five design and simulation perspectives are elaborated. The proposed system consists of an ultra-wide-band microwave compact antenna, a multi-frequency microwave radiometer, and a digital processing unit, all enclosed in a portable arrangement. A modeling and visualization software, processes acquired measurements according to a predefined model of human breast. The system’s concept of operation is based on the fact that a malignant tumor turns out to local temperature increase inside the tissue. By measuring this temperature in successive depths, using different frequency bands in the region of 1–4 GHz, as well as in nearby spatially arranged spots on the human tissue surface, 2-D and 3-D imaging of the temperature distribution are realized. This paper focuses on design and simulation approaches of all system’s aspects. [ABSTRACT FROM PUBLISHER]

A new miniaturized ultra-wideband (UWB) monopole antenna with a broad band, sharp roll-off frequency notch function is presented. A narrow, stepped impedance strip is the radiating element of the antenna similar to conventional narrowband antennas, in order to retain the conventional antenna characteristics such as polarization purity, omnidirectional radiation pattern, etc. The strip is split to create multiple closed resonances and inductors are loaded in series to achieve wide bandwidth. The split portions are inserted one over the other to make the antenna very compact. A new compact dual mode wide band parasitic resonator placed along the feed line, rejects the frequency band ranging from 5.15 to 5.825 GHz which has been allocated for IEEE 802.11a and High Performance Radio Local Area Network (HIPERLAN). The designed antenna was fabricated and the results were measured in an anechoic chamber. The measured results show the ultra-wideband resonance with reflection coefficient values below −10 dB over 3–10.5 GHz with a sharp roll off notch band. [ABSTRACT FROM AUTHOR]

In this paper, we present the smallest form factor microstrip-fed ultra-wideband antenna with quintuple rejection bands for use in wireless sensor networks, mobile handsets, and Internet of things (IoT). Five rejection bands have been achieved at the frequencies of 3.5, 4.5, 5.25, 5.7, and 8.2 GHz, inseminating four rectangular complementary split ring resonators (RCSRRs) on the radiating patch and placing two rectangular split-ring resonators (RSRR) near the feedline-patch junction of the conventional ultra-wideband (UWB) antenna. The design guidelines of the implemented notched bands are provided at the desired frequency bands and analyzed. The measured results demonstrate that the proposed antenna delivers a wide impedance bandwidth from 3 to 11 GHz with a nearly omnidirectional radiation pattern, high rejection in the multiple notched-bands, and good radiation efficiency over the entire frequency band except at the notched frequencies. Simulated and measured response match well specifically at the stop-bands. [ABSTRACT FROM AUTHOR]

In this paper, very compact (12mm×17mm) and simple UWB antenna is proposed. The achieved bandwidth of the presented antenna is from 3.05 GHz to 12.5 GHz and in the most of the bandwidth, the return loss is less than -20dB. In addition to frequency characteristics, time characteristics such as group delay variations for three different antenna positions, namely, front to front, back to back and side by side using CST MW studio are simulated and discussed. To improve the group delay variations, by changing the radius of the circle on the back side of the antenna, the antenna gain in different frequencies will be tuned, therefore, the time domain characteristics of the proposed antenna are greatly improved.

This paper presents the design and realization of a compact ultra-wideband (UWB) antenna with a rectangular notch wireless area network (WLAN) band that has controllable notched bandwidth and center frequency. The UWB characteristics of the antenna are achieved by truncating the lower ends of the rectangular microstrip patch, and the notch characteristics are obtained by using electromagnetic bandgap (EBG) structures. EBGs consist of two rectangular metallic conductors loaded on the back of the radiator, which is connected to the patch by shorting pins. A rectangular notch at the WLAN band with high selectivity is realized by tuning the individual resonant frequencies of the EBGs and merging them. Furthermore, the results show that the bandwidth and frequency of the rectangular notch band could be controlled according to the on-demand rejection band applications. In the demonstration, the rectangular notch band was shifted to X-band satellite communication by tuning the EBG parameters. The simulated and measured results show that the proposed antenna has an operational bandwidth from 3.1−12.5 GHz for |S11| < -10 with a rectangular notch band from 5−6 GHz, thus rejecting WLAN band signals. The antenna also has additional advantages: the overall size of the compact antenna is 16 × 25 × 1.52 mm3 and it has stable gain and radiation patterns.

In this article, a generalized sequential domain patching (GSDP) method for efficient multi-objective optimization based on electromagnetics (EM) simulation is proposed. The GSDP method allowing fast searching for Pareto fronts for two and three objectives is elaborated in detail in this paper. The GSDP method is compared with the NSGA-II method using multi-objective problems in the DTLZ series, and the results show the GSDP method saved computational cost by more than 85% compared to NSGA-II method. A diversity comparison indicator (DCI) is used to evaluate approximate Pareto fronts. The comparison results show the diversity performance of GSDP is better than that of NSGA-II in most cases. We demonstrate the proposed GSDP method using a practical multi-objective design example of EM-based UWB antenna for IoT applications.

In this paper key shaped monopole antenna with and without rectangular slot inserted on feeding strip is proposed for Ultra Wide Band (UWB). This UWB antenna is etched on a 30 x 30mm² commercially available low cost substrate of Flame Recorded Grade 4 (FR4) with thickness of 1.6mm, relative dielectric constant e = 4.4 and dielectric loss tangent = 0.02. One of the industry leading 3D EM software tools for radio frequency (RF) application known as High Frequency Structure Simulator (HFSS) was used to design this UWB antenna. The reflection coefficient Sn of the proposed antenna was found to be less than -10dB and Voltage Standing Wave Ratio (VSWR) is less than 2. It was found that the designed UWB antenna is operable over the entire 3.1GHz - 10.6GHz frequency range. [ABSTRACT FROM AUTHOR]

A Y-shaped ultra-wideband (UWB) monopole antenna containing modified ground plane with five stop bands is presented. An inverted U-shaped slot and a C-shaped slot are placed on Y-shaped radiating patch to achieve two notched bands while three pairs of C-shaped slots are placed at different positions on modified ground plane to achieve three more notched bands. The proposed antenna is designed, fabricated and experimentally tested. The designed Y-shaped antenna has overall dimensions of 36 × 38 × 1.6 mm 3 (0.34 λ l  × 0.36 λ l  × 0.016 λ l ) and has impedance bandwidth 2.86–13.3 GHz at |S 11 | < −10 dB level. Measured band notches are achieved at 3.75/5.43/7.87/8.62/9.87 GHz centre notched frequencies to eliminate worldwide interoperability for microwave access (WiMAX) band (3.45–4.0 GHz), wireless local area network (WLAN) band (5.15–5.90 GHz), X-band for satellite communication (6.77–8.00 GHz), ITU-8 band (8.3–9.1 GHz), and radio navigation (RN) band (9.3–10.6 GHz), respectively. Variation of slot parameter on individual band notch is also investigated. Omnidirectional radiation pattern for XZ-plane and dipole-like radiation pattern for YZ-plane are observed. Stable gain, variation of phase response in linear fashion and group delay <1.3 ns for whole ultra-wideband except at band notches is achieved. [ABSTRACT FROM AUTHOR]

The complexity reduction of receivers in ultrawideband (UWB) communication when time reversal (TR) technique is applied makes it suitable for low-cost and low-power sensor systems. Larger antenna dispersion can generally lead to a less stable phase center and will increase the interference in UWB communications based on pulse radio, whereas a higher antenna gain will result in higher channel gain and further larger channel capacity. To find out the trade-off between antenna gain and dispersion, we performed the channel measurements using different antennas in a dense multipath environment and established the distribution of channel capacities based on the measured channel responses. The results show that the capacity loss caused by antenna dispersion cannot be compensated by antenna gain with line-of-sight transmission to some extent, the effect of phase center on the communication system is negligible, and antennas with smaller time dispersion will have a better energy focusing property and anti-interference performance in TR systems. [ABSTRACT FROM AUTHOR]

In this study, a vehicle mounted antenna for RCIED jamming in the radio frequency band (30 MHz to 3 GHz) is proposed. The proposed antenna integrates a half-bandwidth loop antenna and a slot antenna for bandwidth broadening. The antenna was made low profile for vehicle mounting. Simulation results produced a 800 mm (height, 0.08λ) × 3 240 mm (length, 0.32λ) dimension antenna that was ∼75% decreased in height compared to a 30 MHz broadband one wavelength loop antenna. The dimensions of the antenna were redesigned to 1/10 scale for convenient manufacturing and measurement. The redesigned 1/10 scale antenna was 80 mm (height, 0.008λ) × 324 mm (length, 0.032λ) according to the simulation and measurement results. The −10 dB bandwidth was 100:1(300 MHz to 30 GHz), so when scaled up by a factor of 10, the radio frequency band would be covered with a band of 30 MHz to 3 GHz. For the polarization sum pattern, the low frequency band showed an oval pattern, while the high frequency band showed a butterfly shaped pattern in the horizontal plane, confirming the suitability of the antenna design for RCIED jamming. [ABSTRACT FROM AUTHOR]

A miniaturized spiral antenna with a broadband balun for a partial discharge (PD) localization system is proposed. The proposed antenna has broadband characteristic from 925 MHz to 1.6 GHz and a unidirectional radiation pattern. The overall dimensions of the fabricated antenna are 80 × 80 × 40 mm3, which is the smallest size among antennas for the PD detection system. The measured −10 dB reflection bandwidth starts at 925 MHz, and the measured directivity of the antenna is about 6 dB in the frequency band. [ABSTRACT FROM AUTHOR]

This communication presents a new reconfigurable filtering monopole antenna design with three switchable states for UWB/WLAN applications. The antenna has three independent ports for ultra-wideband state, 2.4 GHz WLAN narrowband state, and 5.8 GHz WLAN narrowband state, respectively. The narrowband state at 2.4 GHz is produced by a first-order microstrip filter using an open-loop resonator, and the narrowband state around 5.8 GHz is obtained by involving a third-order hairpin bandpass filter in the RF path. Frequency reconfiguration is achieved by RF path selection using dc controlled p-i-n diodes. As a result, narrowband filtering responses at desired frequency bands can be achieved. One antenna prototype is simulated, fabricated, and measured. Measured reflection coefficients and radiation patterns demonstrate that the proposed reconfigurable filtering antenna is an eligible candidate for future multifunctional systems incorporating both UWB and WLAN systems. [ABSTRACT FROM AUTHOR]

An ameliorated ultrawide band (UWB) and high-gain microstrip antenna based on planar metamaterial is presented and discussed in this paper. The proposed antenna with a compact size of 32 × 28 × 0.794 mm3 has mesh-shaped patch and patterned ground plane with crossed strip gaps. By means of novel planar metamaterial structure, impedance bandwidth and gain own a significant improvement. The simulations show that the antenna has a super-wide band (less than −10 dB), from 3.06 GHz to 36.4 GHz, covering the entire UWB frequency band (from 3.1 GHz to 10.6 GHz) set by FCC. Within the operating band of concern, the antenna gain can reach as high as 8.02 dB. Due to the surface wave coming from the patterned patch and ground plane, the antenna presents end-fire directional radiation in the higher frequency region. To validate the simulation results, a prototype is fabricated and measured. And the measured results are in good agreement with the simulation results. It is obvious that advantages mentioned above will enable the proposed antenna to be well applied in the short-range wireless communication system. [ABSTRACT FROM AUTHOR]

A 3D-printed tapered cavity-backed flush-mountable wideband antenna for UAV applications is proposed. The antenna consists of a mono-cone and an exponentially tapered cavity, which are fabricated using 3D printing technology. Performance degradation caused by the resonance of a conventional cavity is reduced by tapering the cavity. The antenna has the overall dimensions of 224 mm × 224 mm × 34 mm. The measured 10-dB return loss bandwidth of the antenna is 24.4 GHz ranging from 1.3 GHz to 25.7 GHz (180%). The measured radiation pattern has an omnidirectional characteristic over the operating frequency band. [ABSTRACT FROM AUTHOR]

In this article a microstrip-fed mickey shaped monopole antenna with triple notched band characteristics for ultra-wideband applications is presented. By etching two slots in the ground plane, improved VSWR bandwidth is achieved. Mickey shape radiating patch provides 10 dB return-loss bandwidth from 3.10 to 10.60 GHz. By etching three simple C-shaped slots on the radiating patch, three existing wireless communication systems which interfere with UWB band is removed which includes WiMAX IEEE802.16 (3.30-3.80 GHz), WLAN IEEE802.11a/h/j/n (5.15-5.35, 5.25-5.35, 5.47-5.725, 5.725-5.825 GHz) and X-band downlink satellite system (7.1-7.9 GHz). Experimental results reveal that the proposed antenna exhibits desirable radiation patterns in the far field, resulting omnidirectional like pattern in the H-plane and nearly dipole like pattern in the E-plane. [ABSTRACT FROM AUTHOR]

In this paper, small printed flower-shape triple notch ultra-wideband (UWB) monopole antenna with high band rejection is presented. Notch bands include WiMAX (IEEE802.16 3.30-3.80 GHz), WLAN IEEE802.11a/h/j/n (5.15-5.35, 5.25-5.35, 5.47-5.725, 5.725-5.825 GHz), and X-band downlink satellite system (7.1-7.9 GHz). By including inverted T-shape stub and etching two C-shaped slots on the radiating patch, triple band-notch function is obtained with measured high band rejection (VSWR = 14.52 at 3.58 GHz, VSWR = 15.88 at 5.69 GHz and VSWR = 6.95 at 7.61 GHz) and covers a UWB useable fractional bandwidth of 114.30% (2.74-10.57 GHz = 7.83 GHz). In short the antenna offers triple band-notch UWB systems as a compact multifunctional antenna to reduce the number of antennas installed in wireless devices for accessing multiple wireless networks with wide radiation pattern. The proposed antenna has a small size of about 0.25λ × 0.30λ at 4.2 GHz (first resonance frequency), which has a size reduction of 30% with respect to the earlier published antenna. Both the experimental and simulated results of the proposed antenna are presented, indicating that the antenna is a good candidate for various UWB applications. [ABSTRACT FROM AUTHOR]

In this paper, a novel compact ultra-wideband (UWB) antenna with a quad band-notched function using S-SCRLHs (splited simplified composite right/left-handed) resonator is presented. The S-SCRLHs resonator, which exhibits quadruple resonance, is realized by coupling double S-SCRLH resonator. Then, the S-SCRLHs resonator is integrated into a UWB antenna consisting of modified circular patch. The proposed UWB antenna operates under the frequency range of 3.0-10.7 GHz. This proposed antenna displays a VSWR < 2(the voltage standing wave ratio) across the entire UWB band and compact dimensions of 25 × 20 mm, which is 0.2λ (free space) at 3.0 GHz. By changing the dimension of S-SCRLHs resonator, the notched frequencies can be adjusted appropriately in four bands of 3.6-3.8 GHz (WiMAX), 4.5-4.9 GHz (C-band), 5.6-6.0 GHz (WLAN), and 7.2-7.6 GHz (X-band). The antenna can be applicable in the UWB receiver systems where the four kinds of interference signals corresponding to the four bands can be suppressed. The gain varies from 2.1 to 4.5 dBi with gain values of −2.8, −2.6, −1.5 and −2.4 dBi at respective four notch frequencies. The radiation efficiency is no less than 84% throughout the operational bandwidth. The proposed antenna achieves omnidirectional radiation patterns while also providing rejection at desired notches. [ABSTRACT FROM AUTHOR]

This communication presents a new approach to implement planar antipodal Vivaldi antenna design. A nature fern inspired fractal leaf structure is implemented here. Impedance bandwidth (−10 dB) of the proposed antenna is around 19.7 GHz starting from 1.3 to 20 GHz. The lower operating frequency of this antenna is reduced by 19% with the second iteration as compared to the first iteration of fractal leaf structure. The prototype antenna is fabricated and tested in frequency as well as in time domains to obtain various transfer characteristics along with common antenna parameters. Experimental results show that good wideband feature, stable radiation pattern, and promising group delay of less than 1 ns signatures are obtained, which agree well with the simulated data. The miniaturized proposed antenna structure becomes an attractive choice in microwave imaging applications because of its ultrawide fractional bandwidth at 175%, high directive gain of 10 dBi, and finally appreciably large fidelity factor above (>90%). [ABSTRACT FROM AUTHOR]

A novel planar switchable antenna with a band-notched and multi-resonance performance is proposed. In order to generate single band-notched characteristics, a parasitic element with attaching two stubs is applied. Furthermore, to achieve a switchable function, only one PIN diode is used across a semicircular radiator patch and the parasitic element. When the PIN diode is biased forwardly, the semicircular patch transforms to a circular patch, and an additional resonance is excited at the notch frequency. Additionally, by attaching two L- and T-shaped stubs and cutting a rectangular slit on the radiating patch, new additional resonances are excited, and hence wider impedance bandwidth can be produced. The presented antenna has a compact size of 19.5 × 17 mm2, equal to 0.2 λ0× 0.17 λ0(λ0is the free-space wavelength at 3.1 GHz). The experimental and simulated results show that the antenna has a good radiation behavior within the ultra-wideband frequency range (3.08 to over 14 GHz) and reconfigurable frequency band-notched function in the range of wireless local area network and dedicated short-range communication signals (4.87–6.08 GHz). It is shown that there is virtually no change in the antenna's E-plane and H-plane radiation patterns for the various PIN diode switching conditions, especially at low frequencies. [ABSTRACT FROM AUTHOR]

A compact improved Vivaldi antenna working on 0.8-3.8 GHz was designed by using resistance-loaded and slotting technology. Resistance-loaded can reduce the plane size of antenna and three symmetrical unequal rectangular slots in the antenna radiation part can increase the gain. The improved Vivaldi antenna size is 150x150x0.508 mm³, which can be used in ground penetrating radar. The simulation results and experimental results are presented to validate the performance of the proposed improved structure of Vivaldi antenna. [ABSTRACT FROM AUTHOR]

We present a compact ultra-wideband (UWB) antenna integrated with sharp notches with a detailed analysis of the mutual coupling of the multiple notch resonators. By utilizing complementary split ring resonators (CSRR) on the radiating semi-circular patch, we achieve the sharp notch-filtering of various bands within the UWB band without increasing the antenna size. The notched frequency bands include WiMAX, INSAT, and lower and upper WLAN. In order to estimate the frequency shifts of the notch due to the coupling of the nearby CSRRs, an analysis of the coupling among the multiple notch resonators is carried out and we construct the lumped-circuit equivalent model. The time domain analysis of the proposed antenna is performed to show its validity on the UWB application. The measured frequency response of the input port corresponds quite well with the calculations and simulations. The radiation pattern of the implemented quad-notched UWB antenna is nearly omnidirectional in the passband. [ABSTRACT FROM AUTHOR]

This paper demonstrates the design of a triple band notched ultrawideband circular microstrip patch antenna loaded with Complementary Split RingResonator (CSRR) and S-shaped slot in microstrip feed line. Complementary Split Ring Resonator slot and S-shaped slot are used to produce band notched characteristics for WiMAX band (3.30–3.60 GHz) and WLAN band (5.10–5.80 GHz) respectively. The downlink frequency band (7.25–7.75 GHz) of X-band for satellite communication is notched using Symmetrical Split Ring Resonator Pair (SSRRP) as electromagnetic coupling element near microstrip feed line which produces band stop characteristics. Measured results of fabricated antenna prototype are compared with simulated results and found in correspondence. The VSWR and vector current plots show evidence of the significant suppression in the desired frequency bands. [ABSTRACT FROM AUTHOR]

This article proposes an ultra-wideband coplanar strips (CPS) rectangular spiral antenna that is fed by coplanar waveguide (CPW). The CPS is formed by gradually reducing the width of the CPW ground planes without the need of a balun. The antenna operates in the frequency band (3.5-10.6 GHz) and has miniaturized size of 50 × 40 × 0.508 mm on a Rogers RO4003C substrate. The CPS spiral is terminated with a 100 Ω chip resistor for matching. A parametric study was performed to choose the CPS spiral dimensions. A good agreement is found between simulations and measurements in the radiation pattern and the return loss which was found to be better than 10 dB over the band. The measured peak gain ranges between 1 and 4.7 dBi. [ABSTRACT FROM AUTHOR]

Due to the requirements of increased bandwidth and data transfer rate in wireless communication, cognitive radio (CR) has been proposed as a solution to the spectrum scarcity problem. Regarding the many advantages that ultra‐wideband (UWB) antennas offer, they could be used in CR systems. Simultaneously, by designing a band reject filter for avoiding interference with other applications, like wireless local area network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX), safety communication can be provided. In this work, two novel CRs (so that secondary ports are as non‐planar and uni‐planar parasitic antennas shapes) are presented. Each antenna consists of two ports at the opposite sides; one of them plays as UWB port (first work: 3.1–10.6 GHz and second work: 2.98–11.83 GHz) with filtered WLAN/WiMAX (first work: 4.9–5.8 GHz and second work: 4.9–6.08 GHz) and the other one supports filtered frequency bandwidth (first work: 4.8–6.2 GHz and second work: 5.1–6 GHz). Size reduction occurred in this work with both structures having the same size of 25 × 25 × 0.8 mm3. The designed antennas were measured and results of antennas have agreed well with the simulation analysis. [ABSTRACT FROM AUTHOR]

A compact uniplanar ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna with band-notched characteristic is presented in this paper. The antenna consists of two half circle-slot antennas serving as the radiators and a simple rectangular slot etched on the ground plane. The utilization of a half circle-slot antenna structure results in a significant size reduction compared with the traditional circle-slot antennas. A T-shaped open slot is employed to create a band rejection in WLAN 5.2 GHz. To enhance the port isolation, the back-to-back placement and a rectangular slot on the common ground are utilized. To verify the antenna performance, the proposed antenna is constructed. Over the UWB band of 3.1-10.6 GHz, the measured reflection coefficient is better than −10 dB and the port isolation less than −15 dB with a compact size of 33 × 26 mm2. In addition, the reasonable radiation pattern, gain, and ECC are also obtained. [ABSTRACT FROM AUTHOR]

The antenna performance is affected strongly in proximity of human body in wireless body area network (WBAN). In this study, a fractal ultrawideband antenna is presented, which can operate in free space as well as on-body WBAN scenario, simultaneously. In the design, Koch fractal geometry is used in the monopole as well as in the ground plane of the antenna, which assists to achieve the operational bandwidth up to 122% and stable radiation pattern. In order to analyze the effect of body tissue on antenna performance, a four layered (skin, fat, muscle, and bone) human body tissue model is used. The comparative S11 performance of the antenna on tissue model for on-body WBAN scenarios is evaluated. Moreover, S21 characteristics of antenna for different orientations at various body parts such as abdomen, near forehead, and chest, are measured to acquire the healthcare signals. Local SAR and average SAR performances of the presented antenna are also evaluated on SAR line. Hence, the proposed antenna is a suitable candidate for WBAN applications. [ABSTRACT FROM AUTHOR]

In this paper a multifunctional antenna is presented which offers an ultra-wideband (UWB) operation, an UWB operation with two switchable notches and reconfigurable dual-band operation for WiMAX and WLAN applications, respectively. Total seven functions/states could be achieved from a single antenna using an electronic switching. The antenna uses dual slots on the ground plane to provide a wide bandwidth, ranging from 3.1 GHz to 10.6 GHz. U-shaped slot and C-shaped printed strip in the ground are used to generate two notches at 3.6 GHz (WiMAX) and 5.2 GHz (WLAN/ WiFi) bands, respectively. Moreover, four parasitic strips are added in the feed side to make antenna functional at either 3.6 GHz or 5.2 GHz or both. Total five PIN diodes are required to obtain seven operations from the proposed antenna. Seven structures are fabricated and measured to verify the seven states and results are found in good agreement with estimated results obtained from the simulation. [ABSTRACT FROM AUTHOR]