Ultra wideband patch antenna with a novel folded-patch technique

The authors present the results of a polygonal patch antenna for ultra-wideband applications covering a frequency band from 4.14 to 13.50 GHz. The fabricated antenna achieved a 210 dB impedance bandwidth in excess of 125% with an antenna size of 0.373λo/sub / x 0.373 xλo/sub /0.149λ/spl o/ at its centre frequency. The antenna?s impedance bandwidth is 64% higher than what is currently obtainable with state-of-the-art folded-patch techniques. The proposed patch antenna has a polygonal-shape with a rectangular slot and shorting pins. The analysis of this antenna shows that bandwidth broadening is achieved by using a rectangular slot on the patch that is fed from a folded-patch feed, whereas the reduction in antenna size is achieved through the use of two shorting pins strategically located on the radiating patch.     

Broadband designs of coplanar capacitivelyfed shorted patch antennas

The author presents a coplanar capacitively fed shorted patch antenna for easy fabrication and providing a very wide impedance bandwidth. In this design, a feeding strip is located on the same plane as that of the radiating patch and used to excite the antenna by electromagnetic coupling. Experimental results reveal that the impedance bandwidth of the proposed antenna depends not only on the length and location of the feeding strip but also on the width of the radiating patch. For the optimal result obtained in the design, the 10 dB return-loss impedance bandwidth is as large as 78%. The radiation characteristics of the operating frequencies within the obtained wide bandwidth are also studied and presented.     

Super Compact UWB Monopole Antenna for Small IoT Devices

This article introduces a novel, ultrawideband (UWB) planar monopole antenna printed on Roger RT/5880 substrate in a compact size for small Internet of Things (IoT) applications. The total electrical dimensions of the proposed compact UWB antenna are 0.19 λ_o × 0.215 λ_o × 0.0196 λ_o with the overall physical sizes of 15 mm × 17 mm × 1.548 mm at the lower resonance frequency of 3.8 GHz. The planar monopole antenna is fed through the linearly tapered microstrip line on a partially structured ground plane to achieve optimum impedance matching for UWB operation. The proposed compact UWB antenna has an operation bandwidth of 9.53 GHz from 3.026 GHz up to 12.556 GHz at −10 dB return loss with a fractional bandwidth (FBW) of about 122%. The numerically computed and experimentally measured results agree well in between. A detailed time-domain analysis is additionally accomplished to verify the radiation efficiency of the proposed antenna design for the ultra-wideband signal propagation. The fabricated prototype of a compact UWB antenna exhibits an omnidirectional radiation pattern with the low peak measured gain required of 2.55 dBi at 10 GHz and promising radiation efficiency of 90%. The proposed compact planar antenna has technical potential to be utilized in UWB and IoT applications.     

Internal triple-band folded planar antenna design for third generation mobile handsets

A novel internal triple-band folded planar antenna for mobile handsets is introduced, formed by modifying the geometry of a rectangular patch antenna to include a shorting pin, folded sides, a shorted microstrip stub and a notch. The size of the antenna is successfully reduced to a volume of 34 times 34 times 7 times mm³. The antenna is mounted on a finite ground plane of 50times100 times mm². The impedance bandwidth achieved was 29.7% (equivalent to return loss%%10%dB); this covers the DCS1800, PCS1900 and UMTS 2000 bands. The characteristics of the proposed antenna, including impedance bandwidth and far field radiation patterns are discussed theoretically and experimentally; the simulated and measured results show good agreement. The tuning effects of the geometry parameters on impedance matching of the proposed antenna are also investigated.     

A Novel Compact Highly Isolated UWB MIMO Antenna with WLAN Notch

This paper presents a compact Multiple Input Multiple Output (MIMO) antenna with WLAN band notch for Ultra-Wideband (UWB) applications. The antenna is designed on 0.8 mm thick low-cost FR-4 substrate having a compact size of 22 mm × 30 mm. The proposed antenna comprises of two monopole patches on the top layer of substrate while having a shared ground on its bottom layer. The mutual coupling between adjacent patches has been reduced by using a novel stub with shared ground structure. The stub consists of complementary rectangular slots that disturb the surface current direction and thus result in reducing mutual coupling between two ports. A slot is etched in the radiating patch for WLAN band notch. The slot is used to suppress frequencies ranging from 5.1 to 5.9 GHz. The results show that the proposed antenna has a very good impedance bandwidth of |S11| < −10 dB within the frequency band from 3.1–14 GHz. A low mutual coupling of less than −23 dB is achieved within the entire UWB band. Furthermore, the antenna has a peak gain of 5.8 dB, low ECC < 0.002 and high Diversity Gain (DG > 9.98).     

Compact coplanar waveguide-fed ultra-wideband monopole-like slot antenna

A simple and compact coplanar waveguide (CPW)-fed ultra-wideband (UWB) monopole-like slot antenna is presented. The proposed antenna comprises a monopole-like slot and a CPW fork-shaped feeding structure, which is etched onto an FR4 printed circuit board (PCB) with an overall size of 26 mm x 29 mm x 1.5 mm. The simulation and experiment show that the proposed antenna achieves good impedance matching, consistent gain, stable radiation patterns and consistent group delay over an operating bandwidth of 2.7?12.4 GHz (128.5%). Furthermore, through adding two more grounded open-circuited stubs, the proposed antenna design features band-notched characteristic in the band of 5?6 GHz while maintaining the desirable performance over lower/upper UWB bands of 3.1?4.85 GHz/6.2?9.7 GHz.     

A Novel Broadband Microstrip Antenna Based on Operation of Multi-Resonant Modes

A novel broadband microstrip antenna under operation of TM_1/2,0, TM₁₀ and TM₁₂ modes through a shorting wall and slots is proposed in this paper. Initially, an inverted U-shaped slot is adopted around the feeding point, which achieves a good impedance matching on TM₁₀ mode and separates the patch into two parts. Additionally, a shorting wall is added underneath the edge of smaller patch to excite another one-quarter resonant mode, i.e., TM_1/2,0 mode of smaller patch close to TM₁₀ mode to expand the impedance bandwidth. Further, the antenna width is enlarged and two symmetrical vertical rectangular slots are cut on the patch to reduce the frequency of TM₁₂ mode to form a broadband. Based on the arrangements above, a wide impedance bandwidth with three minima can finally be achieved. The results show that the impedance bandwidth of proposed antenna for |S11|<-10 dB is extended to 26.5% (23.5-30.67 GHz), which is three times of the conventional antenna at same profile. Moreover, a stable radiation pattern at broadside direction is realized over the operating band.     

Ultra-wideband CPW-fed antenna with round corner rectangular slot and partial circular patch

Abstract: A novel coplanar waveguide (CPW)-fed ultra-wideband wide slot antenna is proposed. Because of the round corner of the rectangular slot and partial circular patch, the bandwidth of the antenna is enhanced largely. Good agreement between the measurement and simulation has been achieved. The results show that the impedance bandwidth of the antenna reaches up to 4.5-15.5 GHz for S₁₁ < -15 dB and 2.5-18 GHz for S₁₁ < -10 dB. Meanwhile, a good omni-directional radiation performance has also been achieved.     

Metamaterial-Based Compact Antenna with Defected Ground Structure for 5G and Beyond

In this paper, a unit cell of a single-negative metamaterial structure loaded with a meander line and defected ground structure (DGS) is investigated as the principle radiating element of an antenna. The unit cell antenna causes even or odd mode resonances similar to the unit cell structure depending on the orientation of the microstrip feed used to excite the unit cell. However, the orientation which gives low-frequency resonance is considered here. The unit cell antenna is then loaded with a meander line which is parallel to the split bearing side and connects the other two sides orthogonal to the split bearing side. This modified structure excites another mode of resonance at high frequency when a meander line defect is loaded on the metallic ground plane. Specific parameters of the meander line structure, the DGS shape, and the unit cell are optimized to place these two resonances at different frequencies with proper frequency intervals to enhance the bandwidth. Finally, the feed is placed in an offset position for better impedance matching without affecting the bandwidth The compact dimension of the antenna is 0.25 λL × 0.23 λL × 0.02 λL, where λL is the free space wavelength with respect to the center frequency of the impedance bandwidth. The proposed antenna is fabricated and measured. Experimental results reveal that the modified design gives monopole like radiation patterns which achieves a fractional operating bandwidth of 26.6%, from 3.26 to 4.26 GHz for |S11|<−10 dB and a pick gain of 1.26 dBi is realized. In addition, the simulated and measured cross-polarization levels are both less than −15 dB in the horizontal plane.     

Multipatches multilayered UWB microstrip antennas

The authors present multipatches multilayered ultra-wideband (UWB) microstrip antennas. The antenna comprises a driven patch radiator with five parasitic patch radiators. Two antennas with different dielectric substrate combinations are studied. The antenna with low-high-low dielectric constant substrate combination (Antenna no. 1) has an improved performance in terms of impedance bandwidth, gain, overall antenna size and beam-squinting over the antenna with low-low-low dielectric constant substrate combination (Antenna no. 2). The low-high-low dielectric constant combination consisting of three dielectric substrates, namely low dielectric constant (ϵr = 3.38) for both bottom and upper substrate but, high dielectric constant (ϵr = 6.15) for middle substrate. Five parasitic patches and multi-dielectric layers are used for wide impedance bandwidth and less boresight gain variation with frequency. A measured 10 dB return loss bandwidth of 48% with boresight gain .5.0 dBi is achieved. Antenna no. 1 can have 8% wider impedance bandwidth, 40% overall area reduction and less beam-squinting compared with Antenna no. 2.     

Dual layer stacked rectangular microstrip patch antenna for ultra wideband applications

An antenna consisting of a U-slotted rectangular microstrip patch stacked with another patch of a different size on a separate layer is presented and its performance results are investigated. An equivalent circuit model of this stacked patch design structure is also presented based on an extended cavity model to predict the input impedance. The theoretical input impedance is evaluated from this circuit model and the experimental results support the validity of the model. In this case, stacking with a simple patch adds another resonance to the antenna thus providing a wider bandwidth. The dimension of the top patch is optimised to achieve ultra wide bandwidth. A maximum impedance bandwidth of 56.8% is achieved using this structure, and the return loss |S₁₁|of the antenna is less than -10 dB between 3.06 and 5.49 GHz and the radiation patterns are found to be relatively constant throughout the band. A coaxial feed with Gaussian modulated pulse is used for this antenna.     

Design of a Compact Monopole Antenna for UWB Applications

In this paper, a low cost, highly efficient and low profile monopole antenna for ultra-wideband (UWB) applications is presented. A new inverted triangular-shape structure possessing meander lines is designed to achieve a wideband response and high efficiency. To design the proposed structure, three steps are utilized to achieve an UWB response. The bandwidth of the proposed antenna is improved with changing meander lines parameters, miniaturization of the ground width and optimization of the feeding line. The measured and simulated frequency band ranges from 3.2 to 12 GHz, while the radiation patterns are measured at 4, 5.3, 6 and 8 GHz frequency bands. The overall volume of the proposed antenna is 26 × 25 × 1.6 mm3 ; whereas the FR4 material is used as a substrate with a relative permittivity and loss tangent of 4.3 and 0.025, correspondingly. The peak gain of 4 dB is achieved with a radiation efficiency of 80 to 98% for the entire wideband. Design modelling of proposed antenna is performed in ANSYS HFSS 13 software. A decent consistency between the simulated and measured results is accomplished which shows that the proposed antenna is a potential candidate for the UWB applications.     

At and below the chu limit: passive and active broad bandwidth metamaterial-based electrically small antennas

The solution to the canonical problem of a radiating infinitesimal electric dipole antenna that is centred in a multilayered, concentric metamaterial-based spherical shell system is presented. It is demonstrated that when this system is electrically small, a specifically designed homogenous and isotropic epsilon-negative (ENG) layer can function as a distributed matching element to the antenna enabling a resonant radiation behaviour. A finite element model of the corresponding centre-fed cylindrical dipole antenna-based resonant system confirms that such designed ENG-based spherical layers can act as a distributed matching element, which can be optimised to produce a reactance free, resistively matched and, hence, efficient radiating system. Several limits on the dispersion properties of the homogenous and isotropic ENG media used in these matching layers are considered and their impact on the bandwidth of these resonant systems is established. Although the dispersionless resonant antenna-ENG system has a bandwidth substantially below the Chu limit, the bandwidths of the corresponding dispersive systems are shown to be at or just slightly below the Chu limit. An analytical model of an idealised gaseous plasma-based ENG layer sandwiched between two glass layers, a potential realisation of these metamaterial-based ENG spherical shell systems, is introduced and its solution is used to study these efficiency and bandwidth issues further. Resonant systems based on active ENG metamaterial layers realised with two types of idealised gain medium models are shown to have bandwidths that approach the idealised dispersionless medium values and, consequently, are substantially below the Chu limit     

Broadband low-profile antennas for wireless applications

Two novel broadband low-profile antennas are developed for the mobile terminals of wireless applications. The first one is a quasiplanar antenna which has a height of 0.06lambda₀, where lambda₀ is the free-space wavelength at the centre frequency. The second one is a planar antenna which has a height of 0.056lambda₀. It is demonstrated that the quasiplanar antenna can achieve a bandwidth for VSWR<2 of more than 45%, while the planar antenna realises a bandwidth of more than 40%. More importantly, over these bandwidths the broadband low-profile antennas have a quite constant omnidirectional radiation pattern with a peak gain of around 1 dBi. The antennas are designed on a commonly used RT/Duroid substrate; hence it is easy to integrate with RF front-end circuits. The antenna structures are described and the simulation and experimental results are presented     

A simple dual-band microstrip-fed printed antenna for WLAN applications

A novel microstrip-fed dual-band printed antenna for wireless local area network (WLAN) is presented. The antenna comprises a rectangular and a circular radiating element, which generate two resonant modes to cover 2.4/5.2/5.8 GHz WLAN bands. The design was experimentally verified by constructing the antenna on a FR4 (ϵr = 4.4) dielectric substrate (47 mm x 26 mm x 0.76 mm) and measuring its impedance and radiation characteristics at both the bands. The measured 10 dB return loss (VSWR 2:1) bandwidth in the 2.4G Hz band is 550 MHz (2.1?2.65 GHz) and it covers the bandwidth required for 2.4 GHz WLAN. The 5.2/5.8 GHz resonant mode has a bandwidth of 950 MHz (5.15?6.1 GHz) covering 5.2/5.8 GHz WLAN bands. A rigorous experimental evaluation confirmed that the dual-band printed antenna maintained good radiation characteristics with minimum cross-polarisation levels.     

V-Shaped Monopole Antenna with Chichena Itzia Inspired Defected Ground Structure for UWB Applications

Due to rapid growth in wireless communication technology, higher bandwidth requirement for advance telecommunication systems, capable of operating on two or higher bands with higher channel capacities and minimum distortion losses is desired. In this paper, a compact Ultra-Wideband (UWB) V-shaped monopole antenna is presented. UWB response is achieved by modifying the ground plane with Chichen Itzia inspired rectangular staircase shape. The proposed V-shaped is designed by incorporating a rectangle, and an inverted isosceles triangle using FR4 substrate. The size of the antenna is 25 mm×26 mm×1.6 mm. The proposed V-shaped monopole antenna produces bandwidth response of 3 GHz Industrial, Scientific, and Medical (ISM), Worldwide Interoperability for Microwave Access (WiMAX), (IEEE 802.11/HIPERLAN band, 5G sub 6 GHz) which with an additional square cut amplified the bandwidth response up to 8 GHz ranging from 3.1 GHz to 10.6 GHz attaining UWB defined by Federal Communications Commission (FCC) with a maximum gain of 3.83 dB. The antenna is designed in Ansys HFSS. Results for key performance parameters of the antenna are presented. The measured results are in good agreement with the simulated results. Due to flat gain, uniform group delay, omni directional radiation pattern characteristics and well-matched impedance, the proposed antenna is suitable for WiMAX, ISM and heterogeneous wireless systems.     

Metamaterial superstrate-loaded meandered microstrip-based radiating structure for bandwidth enhancement

We have introduced metamaterial superstrate in microstrip-based radiating structure to increase its bandwidth. Split ring resonators are added as metamaterial metallic inclusion in superstrate of the conventional design. This changes the basic structure of the material. Material properties such as permittivity and permeability changed due to change in the structure. The change in its material properties enhances the bandwidth of the antenna. The antenna is meandered to achieve better performance at the edges which in a way improve the radiation path of the patch. Here, the proposed antenna works on three bands in the range 3–8?GHz. Maximum 60% bandwidth is enhanced in the third band. The voltage standing wave ratio and return loss (S₁₁) of the entire three bands are shown in the paper. The antenna works on 3.51, 4.86 and 7.8?GHz. Design results are obtained by high-frequency structure simulator which is used for simulating microwave passive components.     

Wideband microstrip antennas with sandwich substrate

A broadband microstrip antenna with low?high?low (sandwich) dielectric constant substrate combination using a microstrip line-via feed is presented for ultra-wideband applications. The proposed antenna consists of three dielectric substrates; low dielectric constant substrates that contain the microstrip feed line as well as parasitic patches and a high dielectric constant substrate that contains the driven patch. To achieve a large impedance bandwidth, parasitic patches and microstrip line-via combination feed to the driven patch in the multilayered microstrip antenna are used. The proposed antenna designed, fabricated and measured on the sandwich substrate. The antenna has measured 10 dB return loss bandwidth of 46.9% and directive gain .5.2 dBi at boresight across the impedance bandwidth. The total height of antenna is 5.77 mm or 0.077λ ^{at 4 GHz.}     

Waveform-synthesis method that reduces battery power in an electrically small wideband radiating system

An electrically small antenna is extremely inefficient when operating over a large (multi-octave) bandwidth in a conventional radiating system. As a result, a large amount of prime battery power would be needed to generate sufficient radio frequency (RF) signal power to overcome the poor antenna efficiency and to induce the desired amount of radiation. An alternative method is described in which electronic switches are integrated within a small loop antenna. The switches operate at a rate greater than the RF carrier frequency and are used to synthesise the desired RF current waveform that passes through the loop. This switching circuit replaces the power amplifier in a conventional radiating system. The battery power needed to stimulate a given radiated signal strength is significantly less [a factor of 1/10 at very high frequency (VHF)] compared with the traditional wideband power amplifier/antenna system. The performance of a prototype VHF system is described.     

A Compact Rhombus Shaped Antenna with Extended Stubs for Ultra-Wideband Applications

Ultra-wideband (UWB) is highly preferred for short distance communication. As a result of this significance, this project targets the design of a compact UWB antennas. This paper describes a printed UWB rhombus-shaped antenna with a partial ground plane. To achieve wideband response, two stubs and a notch are incorporated at both sides of the rhombus design and ground plane respectively. To excite the antenna, a simple microstrip feed line is employed. The suggested antenna is built on a 1.6 mm thick FR4 substrate. The proposed design is very compact with overall electrical size of 0.18λ × 0.25λ (14 × 18 mm²). The rhombus shaped antenna covers frequency ranging from 3.5 to 11 GHz with 7.5 GHz impedance bandwidth. The proposed design simulated and measured bandwidths are 83.33% and 80%, respectively. Radiation pattern in terms of E-field and H-field are discussed at 4, 5.5 and 10 GHz respectively. The proposed design has 65% radiation efficiency and 1.5 dBi peak gain. The proposed design is simulated in CST (Computer Simulation Technology) simulator and the simulated design is fabricated for the measured results. The simulated and measured findings are in close resemblance. The obtained results confirm the application of the proposed design for the ultra-wide band applications.