SIW cavity-backed circularly polarized square ring slot antenna with wide axial-ratio bandwidth

In the proposed work, Substrate Integrated Waveguide (SIW) cavity-backed circularly polarized slot antenna for wideband operation is proposed. A square-ring-slot is etched on the top of the SIW cavity, used for radiation To generate the circularly polarized (CP) wave, the slot is placed slightly offset from the centroid of the cavity. By finely optimizing the antenna dimensions, it exhibits a wide axial-ratio (AR) bandwidth of 789 MHz (7.1%) ranging from 10.64 to 11.45 GHz. Moreover, the radiating slot is excited by an SIW based feed by an inductive window, which lead to a wide impedance matching over 1.74 GHz ranging from 9.92 to 11.67 GHz. Due to the SIW cavity-backing structure, the antenna offers unidirectional radiation patterns while maintaining a low-profile and planar compatibility. To validate the proposed design, the antenna is fabricated and experimentally tested in terms of reflection coefficients, AR, gain, and radiation patterns. The simulated and measured results reveal good mutual agreement. Moreover, the proposed antenna is very useful for wideband applications operating in X-band (8–12 GHz)     

Compact stripline-fed meander slot antenna

A meander-type slot antenna fed by a stripline is proposed for use in miniaturised personal communication systems. By varying the slot configuration of the antenna, a 56% smaller antenna to substitute the conventional slot antenna is achieved. Simulated and measured results are presented     

Dual-polarized slot-coupled planar antenna with wide bandwidth

A new dual-polarized slot-coupled microstrip patch antenna is presented, which can achieve high-isolation, low cross-polarization levels, a wide bandwidth, and low backward radiation levels. The coupling slot is an H-shaped slot. For wide bandwidth and easy integration with active circuits, it uses slot-coupled stacked microstrip patches. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. First, a parametric study on the input impedance of the antenna with a single input port is presented. Based on the results, a dual-polarized microstrip antenna is designed, fabricated, and then measured. The measured return loss exhibits an impedance bandwidth of over 20.9% and the isolation between two polarization ports is better than 36 dB over the bandwidth. The cross-polarization levels in both E and H planes are better than 22 dB. The front-to-back ratio of the antenna radiation pattern is better than 21 dB. Both theoretical and experimental results of return loss, isolation, and radiation patterns are presented and discussed.     

Compact oscillating slot loop antenna with conductor backing

An oscillating slot loop antenna working at 4.02 GHz is realised with a low cost GaAs MESFET. A conductor backing is used to obtain a unidirectional radiation pattern     

Compact bandpass filters with wide controllable fractional bandwidth

In this letter, complementary split ring resonators (CSRR) are proposed to design bandpass filters (BPFs) having wide controllable 3-dB fractional bandwidth (FBW). FBW can be varied between 10% and 100%. In addition, filters have the advantages of compactness, sharp rejection, low insertion loss (IL), and low cost. Two prototype fabricated filters of FBW 10.8% and 81.6% show a maximum passband IL of 1.2dB. Filter occupying area is less than 0.25/spl lambda//sub g//spl times/0.15/spl lambda//sub g/, where /spl lambda//sub g/ is the guided wavelength at the midband frequency.     

Compact CPW-fed quasi-circular monopole with very wide bandwidth

Presented is a new CPW-fed quasi-circular monopole antenna, which is composed of a triangle and its tangent circle. This smooth monopole structure reduces the dimensions and improves impedance bandwidth dramatically. The CPW ground is bevelled to form a 50 to 100 Omega impedance transformer. The measured bandwidth defined by VSWR<2 is from 2.55 to 18.5 GHz, i.e. a ratio of about 7.3:1. The proposed monopole exhibits a nearly omnidirectional radiation pattern with very compact size and simple structure, which is suitable for various military and commercial wideband applications     

Elliptical planar monopole antenna with extremely wide bandwidth

A planar monopole antenna with an extremely wide bandwidth is introduced, which is composed of an elliptical monopole patch and a trapeziform ground plane, both printed on the same side of a substrate, and is fed by a tapered CPW feeder in the middle of the ground plane. The simulated and experimental results demonstrate that this antenna achieves a ratio impedance bandwidth of 21.6:1 for VSWR/spl les/2, and exhibits a nearly omnidirectional radiation pattern, while its area is only about 0.19/spl lambda//sub l//spl times/0.16/spl lambda//sub l/ where /spl lambda//sub l/ is the wavelength of the lowest operating frequency.     

Experimental study of large bandwidth three-offsetmicrostripline-fed slot antenna

The proposed novel three-offset shaped microstripline-fed slot antenna has a radiation pattern similar to the conventional microstrip slot antenna and the advantage of more bandwidth. The measured bandwidth is approximately 1.796 octave (VSWR⩽2.0), Experimental results for the impedance loci and the radiation patterns are also presented     

Stacked microstrip antenna with wide bandwidth and high gain

A stacked microstrip antenna with two parasitic elements, one of which increases the impedance bandwidth and the other which enhances the gain, has been investigated experimentally. The effects of each parasitic element have been clarified as well as the characteristics of the stacked three-element antenna and the design procedure for the stacked microstrip antenna have been described     

A monopolar patch antenna with very wide impedance bandwidth

A monopolar patch antenna that utilizes a bandwidth broadening technique is investigated experimentally and numerically. The proposed antenna consists of a monopole that is formed by connecting four trapezoidal plates orthogonally. A circular patch, which is shorted to the circular ground plane by four shorting wires, is placed at the top of the monopole. The antenna possesses 10-and 14-dB return loss bandwidths of 138% and 107.2% respectively, which is about 49 times that of the corresponding monopolar wire-patch antenna. Also, it provides monopole-like radiation patterns over such wide operating bandwidth. As the proposed antenna can achieve such wide impedance bandwidth with relatively low profile, it is very suitable for multi-band mobile communication systems.     

Small patch/slot antenna with 53% input impedance bandwidth

A small microstrip patch/slot antenna, which achieves a very large bandwidth on a relatively thin substrate (about 0.01lambda₀), is presented. The performance is achieved by employing a combination of annular-ring loading on the patch radiator and the use of a crossed-slot for miniaturisation. An additional ring-slot in the ground plane is used to produce the wideband characteristics of the antenna. Simulated and measured results indicate that a 53% fractional impedance bandwidth is achieved with respect to the centre frequency of 1.409 GHz and the size of the antenna is reduced by 50% compared to the conventional circular patch antenna with respect to a given frequency     

Compact microstrip-fed meander slot antenna for harmonic suppression

A novel compact microstrip-fed meander slot antenna is proposed to achieve suppression of harmonics and miniaturisation of the antenna. To obtain these characteristics, a meander-type slot radiator and U-shaped conductor line connected with the ground plane are applied. The real parts of the measured input impedance at the second- and third-harmonic frequencies are nearly zero. In the measured radiation patterns in E- and H-plane, the second- and third-harmonic suppressions are observed to be approximately less than -30 dB.     

Compact linear tapered slot antenna for UWB applications

A novel ultra-wideband (UWB) antenna consisting of a linear tapered slot in the ground plane and a microstrip to slotline transition is investigated. The antenna possesses a wide bandwidth from 2.95?14 GHz for |S₁₁| < - dB and shows stable radiation patterns with an average gain of 3 dBi throughout the band. Measured group delay and transmission characteristics indicate that the antenna has good pulse handling capabilities.     

Compact printed monopole antenna with 24:1 impedance bandwidth

A compact tapered CPW-fed hollowed elliptical printed monopole antenna with extremely wide bandwidth is proposed. The results demonstrate that this antenna achieves a measured impedance bandwidth from 0.44 to 10.6 GHz (24.1:1) for VSWR les 2, and exhibits a nearly omnidirectional radiation pattern, while its area is only about 0.18 times 0.13lambda_l, where lambda_l is the wavelength of the lowest operating frequency.     

Axial-ratio bandwidth enhancement of asymmetric-CPW-fed circularly-polarised square slot antenna

A novel broadband circularly-polarised (CP) square slot antenna fed by an asymmetric coplanar waveguide (CPW) from a corner of the slot is proposed. A CP bandwidth larger than 10% can be attained simply by using an inverted-L tuning stub protruded from the signal line of the CPW. With an additional pair of grounded strips implanted in the slot, the 3 dB axial-ratio bandwidth and the VSWR ⩽ 2 impedance bandwidth can be greatly raised to be as high as 30 and 35%, respectively.     

Compact slot and dielectric resonator antenna with dual-resonance, broadband characteristics

The goal of this study is to improve the bandwidth of a miniaturized antenna. The proposed technique combines a slot antenna and a dielectric resonator antenna (DRA) to effectively double the available bandwidth without compromising miniaturization or efficiency. With proper design it is observed that the resonance of the slot and that of the dielectric structure itself may be merged to achieve extremely wide bandwidth over which the antenna polarization and radiation pattern are preserved. In addition, using the DRA, a volumetric source, improves the radiation power factor of the radiating slot. A miniaturized antenna figure of merit (MAFM) is defined to simultaneously quantify aspects of miniaturized antenna performance including the degree of miniaturization, efficiency, and bandwidth. Figures for various common types of antennas are given and compared with that of the proposed structures. In order to determine the effects of varying design parameters on bandwidth and matching, sensitivity analysis is carried out using the finite-difference time-domain method. Numerous designs for miniaturized slot-fed dielectric resonator antennas are simulated and bandwidths exceeding 25% are achieved. Two 2.4 GHz antennas are built, characterized, and the results compared with theory.     

小型双频E形缝隙手机天线

提出了一种小型的双频E形缝隙手机天线。E形缝隙采用终端开路结构,并雕刻在地板的顶部,使天线的结构更紧凑,减小了天线的尺寸。同时,E形缝隙天线增加了天线的谐振路径,能产生双频宽频带特性,高低频带宽能覆盖GSM900/1800/1900/DCS/PCS/BuleTooth/UMTS/WLAN2400/WiMAX 2600通信频段。实测和仿真的结果基本吻合,验证了这种设计方法的有效性。     

Compact loaded slot ring antenna for circularly polarised radiation

A novel slot-ring circularly polarised antenna is reported. With sectorial slots loading, the axial ratio (AR) bandwidth is increased and the circumference of the slot-ring is also reduced to 0.5 lambda₀ (lambda₀ is the free-space wavelength at the centre frequency). The antenna features a 22.4% impedance bandwidth for |S ₁₁| les -10 dB, a 10.6% bandwidth for AR les 3 dB and stable radiation patterns over the whole operating band.     

A compact wide slot antenna with dual band-notch characteristic for ultra-wideband applications

A new type of ultra-wideband (UWB) antenna with a dual-notched frequency band, compact size of 21?×?28?mm² and a coplanar waveguide (CPW) fed is proposed in this article. Two notched frequency bands are obtained by embedding two U-shaped slots in the radiation patch and a rectangle slot in the ground plane, which can be controlled by adjusting the length of the responding slots. The frequency domain characteristics are investigated and measured. Both the experimental and numerical results show that the proposed antenna has an impedance bandwidth ranging from 3.1?GHz to more than 11.0?GHz in which voltage standing wave ratio is less than 2, expect two notch frequency band, 5–6?GHz (WLAN) and 7.7–8.5?GHz (X-band for satellite communications in China).