Modified octahedron shaped antenna with parasitic loading plane having dual band notch characteristics for UWB applications

The design of a compact modified octahedron shaped dual band notched ultra wide‐band antenna is presented in this article. The impedance bandwidth of the designed antenna has been enhanced by modifying the shape of the radiator by introducing fractal geometry and a modified ground plane. The proposed antenna offered an impedance bandwidth of 2.4 GHz–19.5 GHz (156% Fractional bandwidth). Two rectangular split ring resonator structures are introduced in the radiator to achieve two notched bands which ranges from 3.3 GHz to 3.7 GHz (WiMAX) and 5.15 GHz–5.85 GHz (WLAN) band. The antenna gain varies from 1 to 4 dBi over the operating band except the notched bands. The overall dimension of the designed antenna has a compact size of 33 × 40 mm². The experimental and simulation results are in good agreement. The proposed antenna has wider bandwidth and smaller dimension over the already reported in the literature. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:426–434, 2016.     

Design of high gain/directional ultra‐wideband antenna for radar imaging systems

A compact size of 40 × 40 mm² ( λ₀ × λ₀ ) semi‐elliptical slotted ground structure (SESGS) directional ultra‐wideband (UWB) antenna is proposed for radar imaging applications. A vertical semi‐elliptical slot is inserted into ground and subsequently, an axis of semi‐ellipse is rotated diagonally (with 45°) in direction of the substrate. Axes of semi‐ellipse are optimized symmetrically around the circular patch to work antenna as a reflector. Furthermore, semi‐elliptical slot is rotated horizontally (with 90°) again to improve the impedance bandwidth. Proposed antenna achieves fractional bandwidth around 83% covering the UWB frequency range from 4.40 to 10.60 GHz (S₁₁ < ?10 dB) having 4.5/6/7/8/9.3/10.2 GHz resonant frequencies. Also, antenna is capable to send low‐distortion Gaussian pulses with fidelity factor more than 95% in time‐domain. Measured gain and half power beam width (HPBW) are 6.1‐9.1 dBi and 44°‐29° in 4.40‐10.60 GHz band, respectively, which show an improvement of 1‐3 dBi in gain and half power beam‐width is reduced by 5°‐10° when compared with previously designed antennas. Experimental results show good agreement with CST simulation.     

Compact UWB flexible elliptical CPW‐fed antenna with triple notch bands for wireless communications

A coplanar waveguide (CPW)‐fed flexible elliptical antenna with triple band notched characteristics is presented in this article. The designed antenna consists of an elliptical patch and slots incorporated CPW feed line to cover the bandwidth requirements for ultra‐wideband (UWB) applications. The designed UWB antenna has a fractional bandwidth of about 166.19% (1.20‐13 GHz) with a center frequency of 7.1 GHz in simulation and about 170.10% (1.05‐13 GHz) with a center frequency of 7.025 GHz in measurement. The overall dimension of the proposed flexible antenna is 45 × 35 × 0.6 mm³. The triple notched bands are realized by designing with circular shaped split‐ring‐resonators (SRRs) and defected ground structure (DGS). According to the measurement, first notched band (2.0? 2.70 GHz) is generated for rejecting 2.4 GHz WLAN by introducing a single circular ST‐SRR on the radiating patch. The second notch (3.45‐3.80 GHz) is obtained by embedding another circular ST‐SRR on the patch to mitigate the interference of 3.5 GHz Wi‐MAX system. Finally, due to presence of DGS, third notch (5.15‐6.20 GHz) is produced which suppresses the interference from 5.5 GHz Wi‐MAX and 5.2/5.8 GHz WLAN systems. The proposed antenna offers excellent performance in different flexible conditions that confirm its applicability on curved surfaces for UWB systems.     

Design and analysis of slot antenna with band notch function

In this article, the design, simulation, and construction of a novel wide rectangular slot antenna fed by a 50 Ω coplanar waveguide (CPW) are presented and investigated for multifunctional communication systems. The physical dimension of the antenna is 29 mm (length) × 32 mm (width) × 1.6 mm (thickness). Detailed simulations and experimental investigations are performed to understand its behavior and to optimize for 2.4 GHz wireless local area network (WLAN) and ultra wideband (UWB) operations. The proposed slot antenna is etched on an FR4 substrate with a thickness of 1.6 mm and relative permittivity of 4.4. To improve the impedance matching, a stepped stub structure with CPW feed technique is used. According to the measured results, the proposed antenna has a large bandwidth from 2.1 to 11.6 GHz for voltage standing wave ratio (VSWR) less than 2, totally satisfying the requirement of 2.4 GHz WLAN and UWB systems, while providing the required band notch function from 5.1 to 5.9 GHz. The study of time domain characteristics and surface current distributions also indicate the band‐notched function of the antenna. The radiation patterns display nearly omnidirectional performance and the antenna gain is stable except for the rejected frequency band (5.1–5.9 GHz). Moreover, group delays are within 1.5 ns except for the notch‐band. It is observed that the simulated and experimental results have good agreement with each other. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

A low‐profile quad‐port UWB MIMO antenna using defected ground structure with dual notch‐band behavior

A compact (45 × 45 × 1.6 mm³) ultrawide‐band (UWB), multiple‐input multiple‐output (MIMO) design using microstrip line feeding is presented. The proposed design comprises four elliptical monopoles placed orthogonally on a cost‐effective FR‐4 substrate. In order to improve the impedance bandwidth and lessen the return loss of the MIMO antenna, defects in ground plane are created by etching symmetrical square slots and half‐rings. Moreover, a different method (of unsymmetrical H‐shaped slot with C‐shaped slot) was proposed into the patch to introduce dual‐band rejection performance from UWB at center frequency 5.5 GHz (covering lower WLAN as well as upper WLAN) and 7.5 GHz (X band). In addition, a stub is introduced at the edge of each defected ground structure to obtain isolation >–22 dB covering entire performing band from 2 to 16.8 GHz (where, S₁₁ < –10 dB). The proposed design has miniaturized size, very low envelop correlation coefficient less than 0.1, stable gain (2‐4 dBi except for notch bands). Furthermore, various MIMO performance parameters are within their specifications, such as diversity gain (= 10 dB), total active reflection coefficient (<–5 dB, and channel capacity loss (<0.35 bits/s/Hz). The presented design is optimized using the HFSS software, and fabricated design is tested using vector network analyzer. The experimental results are in good agreement with the simulation results.     

A novel compact self‐similar fractal UWB MIMO antenna

A novel compact self‐similar fractal ultra‐wideband (UWB) multiple‐input‐multiple‐output (MIMO) antenna is presented. This fractal geometry is designed by using iterated function system (IFS). Self‐similar fractal geometry is used here to achieve miniaturization and wideband performance. The self‐similarity dimension of proposed fractal geometry is 1.79, which is a fractional dimension. The antenna consists of two novel self‐similar fractal monopole‐antenna elements and their metallic area is minimized by 29.68% at second iteration. A ground stub of T‐shape with vertical slot enhances isolation and impedance bandwidth of proposed MIMO antenna. This antenna has a compact dimension of 24 × 32 mm² and impedance bandwidth (S₁₁ < ?10 dB) of 9.4 GHz ranging from 3.1 to 12.5 GHz with an isolation better than 16 dB. The various diversity performance parameters are also determined. There is good agreement between measured and simulated results, which confirms that the proposed antenna is acceptable for UWB applications.     

A broadband circularly polarized monopole antenna

A compact modified C‐shaped monopole antenna with broadband circular polarization is proposed, fabricated and measured. The antenna structure is simple and only consists of combined modified C‐shaped radiation patch and an improved ground plane with the overall size of 25 × 25 × 1 mm³. By cutting the corner on the modified C‐shaped patch and adding triangular stubs on the ground plane, the wide impedance bandwidth and axial ratio bandwidth are achieved. The design process of the antenna is given, and the circular polarization mechanism of the circularly polarized antenna is analyzed from the surface current distributions. The measured impedance bandwidth is 95.2% (4.4‐12.4 GHz) with return loss better than 10 dB, and the measured 3 dB axial ratio bandwidth is 96.8% (4.42‐12.72 GHz). The peak gain is above 3.0 dBi within the working band, which indicates that it is suitable for application of ultra‐wideband (UWB) wireless communication systems and satellite communication systems.     

Circular polarized dual‐band antenna for WLAN/Wi‐MAX application

A novel square ring printed antenna has been suggested for dual‐band circular polarization (CP). The geometry contains a square patch and a square ring structure for dual‐band operation. Circular polarization is achieved using triangular cut at the boundary and right angle bend with inner perturbation. The suggested antenna is excited from the lower layer through electromagnetic (EM) coupling technique. The antenna shows good impedance bandwidths of 90 MHz (2.43‐2.52 GHz) and 800 MHz (5.7‐6.5 GHz, respectively. The antenna shows 3 dB axial ratio bandwidth of 20 MHz at lower band and 120 MHz at upper band with improved gain > 6 dBi. The simulated and measured results are well agreed with each other. The antenna is promising wideband operation at the upper band. This antenna was implemented on fiberglass reinforcement laminated Arlon substrate with dielectric constant (?_r = 2.55), and the overall physical dimension of 30 × 30 × 3.048 mm³. The designed antenna can be extensibly applicable in WLAN/Wi‐MAX communication. The presented antenna is designed using hyperlynx IE3D and the simulated results are presented.     

A miniaturized printed monopole antenna for 5.2‐5.8 GHz WLAN applications

In this article, a new design of a compact printed rectangular antenna for wireless local area network (WLAN) applications in 802.11a is investigated. The defected ground structure (DGS) technique is successfully used to reduce the ground plane by cutting a large slot to achieve significant miniaturization. The ground plane structure consists of inverted ‘L’ shape. The rectangular radiating element has a size of 6 × 5 mm² and is connected to a microstrip transmission feed line. The simulated and measured resonance frequency of the single‐band antenna is approximately 5.8 GHz and may cover an impedance bandwidth of 1 GHz for the measurement and 1.65 GHz for the simulation. The simulated and the measured data are in good agreement. The proposed antenna is very compact (10 × 6 mm²) and its impedance bandwidth is suitable for the 5.2‐5.8 GHz WLAN communication systems.     

Penta‐band notched ultra‐wideband monopole antenna loaded with electromagnetic bandgap‐structures and modified U‐shaped slots

In this article, a planar monopole penta‐notched ultra‐wideband (UWB) antenna is designed and investigated. Three notches (2.81 GHz radar surveillance, 3.38 GHz WiMAX, and 3.87 GHz C‐band satellite downlink) have been realized by integrating three modified U‐shaped slots on the radiating surface. Furthermore, to create two additional notches (2.33 GHz ISM band and 5.75 GHz WLAN), two meander line electromagnetic bandgap (EBG); one located near to the feed line and another on the radiating surface, have been introduced in the design. These unit cells play a fundamental role in generating notches at higher as well as lower frequencies. The proposed antenna possesses an overall size of 34.9 × 31.3 × 1.6 mm³ and has been designed over FR4 substrate. A 50 Ω microstrip line is used to feed the antenna. The antenna without any extra arrangement exhibits an impedance bandwidth of 7.6 GHz. A parametric analysis is studied in detail to observe the band rejection characteristics. The ANSYS HFSS simulation software is used for simulating the proposed design structures. For validation purpose, a prototype is fabricated and characterized. A very good agreement is achieved between simulated and measured results.     

A new printed log‐periodic dipole array (PLPDA) antenna with bandwidth broadening and gain improving

A broader impedance bandwidth and higher gain printed log‐periodic dipole array antenna fed by half‐mode substrate integrated waveguide (HMSIW) is proposed in this letter for ultra‐wideband (UWB) wireless communication applications. The bandwidth of the reference antenna (5.1‐11.4 GHz) is expanded by 1.3 GHz by introducing a new resonance frequency with additional patches. Moreover; gain is enhanced over full band by attaching metal plate to narrow beam and adding directors to attract energy radiated by dipoles. A simulation analysis of the improved antenna with broader bandwidth of 4.1 to 11.7 GHz and higher gain is presented, along with a design procedure and experimental results. Measurement results are consistent with simulation results, which verifies the feasibility of this technique.     

An ultra wideband “OM” shaped DRA with a defected ground structure and dual polarization properties for 4G/5G wireless communications

This research article reports a new Dielectric Resonator Antenna (DRA) with its Dielectric resonator (DR) modified to an “OM” shape for UWB (3.1‐11.1 GHz), to support high data rate multimedia applications for 4G/5G communications. The proposed DRA reports a peak gain of 7.68 dB and a dual polarization behavior for a frequency band from 6 to 11.1 GHz. It has overall antenna dimensions of 50 × 40 × 4.87 mm³ and is fabricated on a commercially available Rogers RT 5880 substrate (with ε_r = 2.2), which is fed using a microstrip feedline with a P‐type transformer that offers an input impedance of 50 Ω to the DR. A conformal strip between the feedline and the OM shaped DR improves the impedance matching at the UWB frequency response of the DRA. This UWB frequency response is mainly because of its optimized “OM” shaped DR structure that excites a TE₁₁₁ mode at 4.9 GHz and two higher order modes TE₂₁₁ and TE₂₂₁ at resonant frequencies of 7.2 and 8.35 GHz, respectively. Additionally the proposed OM shaped DR also generates orthogonal modes of TE₂₁₁^x and TE₂₁₁^y at 6.5 and 7.2 GHz and TE₂₂₁^x and TE₂₂₁^y at 8.35 and 10 GHz, respectively. The proposed DRA therefore exhibits an elliptically polarized behavior with axial ratio bandwidth of 5.1 GHz (≤10 dB) from 6 to 11.1 GHz. A measured impedance bandwidth of 5.25 GHz from 3.8 to 9.05 GHz and 1.5 GHz from 10 to 11.5 GHz and a peak‐measured gain of 7.68 dB at 10.5 GHz (with an average gain of 4.6 dB) has been reported for the proposed DRA. An UWB performance, with good gain properties and an elliptically polarized behavior allows the proposed “OM” shaped DRA to be suitable for short range 4G/5G UWB wireless communications for future multimedia rich WPAN (wireless personal area networks), WLAN, Wi‐MAX, INSAT applications, satellite applications, and X band RADAR (for defense communication) applications.     

A CPW‐fed UWB MIMO antenna with integrated GSM band and dual band notches

This article presents a coplanar waveguide fed global system for mobile communications band integrated ultra wide band (UWB) multiple input multiple output (MIMO) antenna with single and dual notch band characteristics. The novelty of the antenna lies in its design as all the unit cells of the proposed UWB MIMO antenna structure are orthogonal to each other therefore the additional isolation elements responsible for achieving high isolation are not required consequently making proposed antenna design simple and easy to fabricate. In this context, 2 MIMO systems have been designed. The first MIMO system is consisting of a dual port antenna whereas the second MIMO system is a printed quad port antenna; further single and dual notch band are achieved in the proposed multi‐port MIMO antenna. The antenna shows pattern diversity throughout the impedance bandwidth range. The gain of the antenna varies from 4 to 8.48 dBi. The 2 band notches are achieved at 4.8 and 7.7 GHz in the UWB range. The proposed antenna is fabricated and it is found measured results are in good agreement with simulated results.     

Compact wide band directional antenna using cross‐slot artificial magnetic conductor (CSAMC)

In this article a novel wide‐band artificial magnetic conductor (AMC) based wideband directional antenna is presented for ultra‐wideband (UWB) applications. The proposed novel cross‐slot AMC (CSAMC) achieves wide ±90° reflection phase bandwidth of 4.07 GHz (44.69%) and is used as a reflector. The overall antenna structure is designed with 4 × 4 CSAMC unit cell array and has very compact size of (0.584λ₀ × 0.584λ₀). The proposed structure improves the radiation properties and exhibits 91.5% (3.13‐8.41 GHz) impedance bandwidth (VSWR ≤2). Additionally, it results in significant improvement in gain and front to back ratio. The proposed antenna is fabricated and its measured performance is in good agreement with simulation results.     

Ultrawideband circularly polarized antenna with dual band‐notched characteristics

This article presents an ultrawideband (UWB) crossed dipole antenna with circularly polarized (CP) and dual band‐notched characteristics. The proposed design is based on two orthogonal tapered dipoles for UWB CP operation and a square‐shaped cavity for high broadside gain over the entire operating bandwidth (BW). To generate dual band‐notched characteristics, two separated slots are inserted into each dipole's arm. This antenna yields measured impedance BW of 100% (3.2‐9.6 GHz) with dual‐band rejection centered at 5.2 and 5.8 GHz. Correspondingly, dual rejected bands are also observed in the original UWB CP band, which ranges from 3.2 to 8.2 GHz. Additionally, the proposed antenna exhibits high broadside gains better than 6.2 dBic and radiation efficiency greater than 82%.     

A modified split ring resonator based printed compact monopole UWB antenna with spiked elliptical radiator having five band rejection features

A coplanar waveguide (CPW) fed printed compact monopole antenna with five band rejection features is presented. Wide bandwidth was achieved by beveling the lower part and adding a modified ellipse on the upper portion of the patch. An inverted circular arc, single circular split ring resonator (SRR) with wide opening and two symmetrical circular single SRRs were embedded for obtaining three stop‐band characteristics. Two symmetrical slits were inculcated in the ground forming defected ground structure (DGS) to get another stop‐band characteristic. Two concentric rectangular modified SRRs were etched to obtain a higher frequency stop‐band feature. The proposed antenna was designed, fabricated, and experimentally tested for the validation of results. The overall dimensions of the proposed antenna were 29 mm × 24 mm × 1.6 mm. The measured impedance bandwidth of the antenna was 2.87 to 13.3 GHz at | S₁₁ |< ? 10 dB. The measured results show that the proposed antenna has five band notches centred at 3.96, 4.35, 5.7, 8.54, and 9.95 GHz to reject WiMAX band (3.65‐4.04 GHz), ARN band (4.29‐5.18 GHz), WLAN band (5.5‐6.9GHz), ITU‐8 band (7.37‐8.87), and amateur radio band (9.2‐10.3 GHz) respectively. The proposed antenna maintains omnidirectional radiation pattern in H‐Plane and dumbbell‐shape radiation pattern in E‐plane. Further, stable gain over the whole UWB except at notched frequency bands was reported.     

Meander line MIMO antenna for 5.8 GHz WLAN application

A four port compact low profile planar MIMO antenna with meander line radiators and with polarization diversity effect has been proposed to cover 5.8 GHz wireless local area network application. The proposed MIMO antenna has ?10 dB impedance bandwidth of 1.4 GHz (5.3–6.7 GHz) along with the compact size of 38 × 38 mm² and an envelope correlation coefficient (ECC) of less than 4 × 10^?4 in the whole band. The proposed antenna resonates at 5.8 GHz frequency, having return loss of ?43.2 dB. The isolation between diagonal and opposite ports is more than 10 and 12 dB, respectively, in the presented frequency band. The total active reflection coefficient frequency response shows more than 1.0 GHz of bandwidth in the whole band. The antenna gain is more than 4.0 dBi in the operating frequency band. The radiating elements are very close to each other to make the design very compact.     

Compact ultra‐wideband slot antenna with three notched‐band characteristics

A very compact ultra‐wideband (UWB) slot antenna with three L‐shaped slots for notched‐band characteristics is presented in this article. The antenna is designed and fabricated using a new stepped slot with different size, integrated in the ground plane, and excited by a 50 Ω microstrip transmission line. The stepped slot is used to minimize the dimensions of the antenna and to achieve an impedance bandwidth between 2.65 and 11.05 GHz with voltage standing wave ratio (VSWR) less than 2. The length of the stepped slot is equal to a quarter wavelength to create a resonance in the desired frequency. Three L‐shaped slots with various sizes are etched in the ground plane to reject three frequency bands in C‐band (3.7‐4.2 GHz), WLAN (5.15‐5.825 GHz), and X‐band (7.25‐7.75 GHz), respectively. The notched‐band frequency can be controlled by changing the length of the L‐shaped slot. The proposed antenna has a very small size (20.25 × 8 × 1.27 mm³) compared with previous works. The measured and simulated results show a good agreement in terms of radiation pattern and impedance matching.     

Coplanar waveguide‐fed electrically small dual‐polarized short‐ended zeroth‐order resonating antenna using Ω‐shaped capacitor and single‐split ring resonator for GPS/WiMAX/WLAN/C‐band applications

This work explains the design and analysis of a triple‐band electrically small (ka = 0.56 < 1) zeroth‐order resonating (ZOR) antenna with wideband circular polarization (CP) characteristics. The antenna compactness is obtained due to ZOR frequency of composite right/left‐handed (CRLH) transmission line (TL) and wideband CP radiation are achieved due to the introduction of single‐split ring resonator and asymmetric coplanar waveguide fed ground plane. The proposed antenna obtains an overall electrical size including the ground plane of 0.124 λ₀ × 0.131 λ₀ × 0.005 λ₀ at 1.58 GHz and physical dimension of 23.7 × 25 × 1 mm³ are achieved. The antenna provides a size reduction of 44.95% compared to a conventional monopole antenna. The novelty behind the ohm‐shaped capacitor is the generation of extra miniaturization with better antenna compactness. The antenna provides dual‐polarized radiation pattern with linear polarization radiation at 1.58 and 3.54 GHz, wideband CP radiation at 5.8 GHz. The antenna measured results shows good impedance bandwidth of 5%, 6.21%, and 57.5% for the three bands centered at 1.58, 3.54, and 5.8 GHz with a wider axial ratio bandwidth (ARBW) of 25.47% is obtained in the third band. The antenna provides a higher level of compactness, wider ARBW, good radiation efficiency, and wider S₁₁ bandwidth. Hence, the proposed antenna is suitable for use in GPS L1 band (1.565‐1.585 GHz), WiMAX 3.5 GHz (3.4‐3.8 GHz) GHz, WLAN 5.2/5.8 GHz (5.15‐5.825 GHz), and C‐band (4‐8 GHz) wireless application systems.