Dual-broadband multistandard printed slot antenna with a composite back-patch

A square slot antenna fed by a coplanar waveguide for dual-band multistandard applications is presented. Printed on the back of the square slot is a composite patch formed by an annular metal ring inscribed by a circular patch. Appropriate design of the composite back-patch resulted in five resonant bands, the first (last) two of which were combined to form a lower (upper) operating band. The ratio of the two operating band centre frequencies can be tuned larger than 2.5. A pair of notches was embedded in the annular metal ring to further broaden the lower (upper) operating band up to a fractional bandwidth of 37% (20%). The measured results indicate that the proposed antenna can cover the frequency bands of the following wireless communication standards: digital communication system, personal communication services, universal mobile telecommunications system and 2.4/5-GHz wireless local-area networks.     

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.     

Analysis and design of broadband U-slot cut rectangular microstrip antennas

Broadband microstrip antenna using variations of U-slot has been widely reported. However, in most of the reported work, an in-depth explanation about the mode introduced by U-slot and procedure to design U-slot cut antennas at any given frequency is not explained. In this paper, first an extensive analysis to study the broadband response in symmetrical and a new configuration of asymmetrical U-slot cut rectangular microstrip antennas is presented. The U-slot tunes higher-order orthogonal mode resonance frequency of the patch with respect to fundamental mode to realise wider bandwidth. Further formulation in resonant length at modified patch modes in symmetrical U-slot cut antenna is proposed. Frequencies calculated using these formulations show closer agreement with simulated and measured results. Using proposed formulations, a procedure to design U-slot cut antenna at different frequencies over 800–4000 MHz range which shows broadband response is explained. Thus, the proposed work gives an insight into the functioning of widely used U-slot cut antennas and the formulations will be helpful for designing at any given frequency.     

Segmentation analysis of loaded microstrip antenna

Abstract

A microstrip antenna for dual‐frequency operation has been investigated. The frequency can be controlled by placing PIN diodes at appropriate locations in the patch. The cavity model and segmentation method are used to analyze the operation frequency, input impedance, and radiation pattern. Finally, experimental data are compared with theoretical predictions.     

Microstrip-fed dual-frequency annular-slot antenna loaded by split-ring-slot

A compact dual-band annular-slot antenna loaded by a concentric split-ring-slot is presented. A stepped microstrip feedline enables the control of the coupling and provides good matching. The annular-slot is connected to the split-ring-slot by a rectangular slot, which increases the surface of the current path, thus notably reducing the resonant frequency for a given size. The embedded split-ring-slot structure allows many resonant modes to be realised. By tuning the key parameters, these operating modes and their bandwidths can be controlled. A wide bandwidth can be realised for either the lower band, upper band or both bands simultaneously, depending on the application. Measured results show that the bandwidths in the region of 45?15% and 32?8.4%, can be provided for the lower and upper bands, respectively. For the case where a wideband response is required for both bands, it is shown that 26 and 32% can be realised. A 30% miniaturisation is also achieved compared with conventional annular ring slot antennas.     

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.     

Design of circular polarisation microstrip patch antennas with complementary split ring resonator

A novel design of circular polarisation microstrip patch antennas based on the complementary split ring resonator is numerically evaluated and experimentally verified. The non-resonant property of complementary split ring resonator is used as an asymmetric perturbation to excite the square microstrip patch antenna for circular polarisation radiation. The detailed parameters of the complementary split ring resonator on the circular polarisation radiation are studied.     

Left-handed L-band notch bandstop filter with significantly reduced size

An innovative compact microstrip line left-handed (LH) L-band notch bandstop filter is presented, validated by full-wave simulations and demonstrated by experiments, showing that the size of the filter can be significantly reduced by employing the LH transmission line (TL) metamaterials. The proposed notch bandstop filter was constructed using coupled line coupler loaded with 90deg LH TL. The size of the fabricated LH filter is 4.4 times smaller than that of the filter loaded with -270deg conventional TL and nearly two times smaller than that of the filter loaded with -270deg meandered TL. The filter has a centre frequency of 1.164 GHz and a fractional bandwidth of 0.51%. The loaded quality factor of the filter is 197, indicating 64 and 97% increases in comparison with the conventional and meandered TL filters, respectively     

Complementary split ring resonator metamaterial to achieve multifrequency operation in microstrip-based radiating structure design

Following recent findings on metamaterials, a miniaturized microstrip patch antenna loaded with a complementary split ring resonator (CSRR) was investigated for multiband operation. The proposed structure has a CSRR loaded in the base of the antenna to improve its performance and to make it a metamaterial. Metamaterials exhibit qualitatively new electromagnetic response functions that cannot be found in nature. The CSRR-loaded base allows simultaneous operation over several frequencies. Here, a total of seven bands were achieved by loading the patch antenna with the CSRR. The seven bands were centered around frequencies of 4.33 GHz, 5.29 GHz, 6.256 GHz, 7.066 GHz, 7.846 GHz, 8.86 GHz, and 9.75 GHz. Design results were obtained by using a high-frequency structure simulator that is used for simulating microwave passive components.     

Frequency domain analysis of microstrip filters and antennae using an adaptive frequency sampling moment method

In this paper, an adaptive frequency sampling technique is applied to the moment method for the analysis of microstrip filters and patch antennae. The analysis of microstrip low-pass filter and patch antenna in the frequency domain has been usually done with uniform frequency step. An adaptive frequency sampling technique can significantly reduce the time taken for the analysis through the frequency range without reducing the accuracy of the results.     

Electronically controlled spoof localized surface plasmons on the corrugated ring with a shorting pin

We have demonstrated that spoof localized surface plasmons (LSPs) can be controlled by loading a shorting pin into the corrugated ring resonator in the microwave and terahertz (THz) frequencies. Electronical switchability and tunability of spoof LSPs have been achieved by mounting Schottky barrier diodes and varactor diodes across the slit around the shorting pin in the ground plane. An electronically tunable band-pass filter has been demostrated in the microwave frequencies. Such electronically controlled spoof LSPs devices can find more applications for highly integrated plasmonic circuits in microwave and THz frequencies.     

Influence of split ring resonators on the properties of propagating structures

The study of a 50 Omega microstrip line and microstrip resonators loaded with resonant elements called split-ring resonators (SRRs) is presented. The two different filtering phenomena observed lead to make an analogy with those observed when waveguides are loaded with these elements. So, in order to make this analogy, the different results obtained with the SRRs loaded in a propagating and an under cut-off waveguide are shown. Then, another technique to achieve and even improve these results is presented. The technique consists of using, respectively, a 50 Omega microstrip line and capacitive-gap-coupled microstrip resonators instead of the propagating and under cut-off waveguides. The numerical and experimental results obtained with the two structures (waveguides and microstrip lines) are compared and discussed. This study shows that the combination of SRRs with guiding structures helps in the design of compact structures, but an enhancement of the performances needs a better fabrication accuracy     

Scattering properties of patch antennas loaded with inhomogeneous substrates via a combined spectral domainmoment method

Abstract

In this paper a combined spectral domain-moment method is proposed in order to investigate the scattering properties of microstrip patch antennas with inhomogeneous substrates. The closed analytical expressions for the spectral dyadic Green's functions for different inhomogeneity profiles both in the rigorous and in the asymptotic form are obtained. A method of moments (MoM) formulation involving these expressions and using roof-top subdomain expansions is developed in order to calculate the radar cross-section for the antennas under analysis. Finally, different rectangular geometry patch shapes are considered (rectangular itself, L-patch, cross-patch, rectangular ring, etc.) and, for all of them, the monostatic radar cross-sections, compared to those obtained by using homogeneous substrates, are improved.     

双通带带通滤波器的分析与设计

基于方型环与开路线相结合的结构设计了一种新型微带双通带带通滤波器.该滤波器通过调节方型环与开路线的尺寸分别获得两个通带.经仿真优化,并制作了实物模型.测试结果表明该滤波器能够工作在2.365 GHz和4.465 GHz,插入损耗都小于3 dB.测量结果与仿真曲线一致性较好.该滤波器结构简单、设计方便、体积小、易于加工,便于与其它电路集成,可以广泛应用于射频前端.     

Size reduction of microstrip patch antennas with left-handed transmission line loading

A procedure for designing an electrically small microstrip patch antenna (MPA) is developed, wherein the length of a side of the MPA is reduced to significantly less than a half-wavelength. The MPA is loaded with a resonant circuit equivalent to that of a left-handed transmission line to artificially increase the effective wavelength of the device, thus creating a resonance equivalent to, but at a lower frequency than the unloaded {10} mode. The field distribution in the loaded MPA remains relatively unperturbed, unlike the {0} mode case that attempts to decrease the size by introducing a shorting-post; consequently, very low cross-polarisation behaviour is observed. The theory to predict the full spectrum of resonant frequencies of the antenna is developed, with finite-difference time-domain simulations used to finalise the antenna design. Finally, an electrically small ((lambda/6)times(lambda/4)) and thin (相似文献   

Input impedance of probe-fed rectangular microstrip antennas with variable air gap and varying aspect ratio

The input impedance of a rectangular microstrip patch with a variable air gap has been studied theoretically and experimentally. Unlike earlier investigations, the influence of the air gap along with the varying patch width in changing the patch impedance is thoroughly examined. An efficient computer aided design formulation is developed and used for this study, and the computed results are experimentally verified. Superiority of the present theory compared to some earlier models is also indicated.     

Modelling of Wideband Concentric Ring Frequency Selective Surface for5GDevices

Frequency selective surfaces (FSSs) play an important role in wireless systems as these can be used as filters, in isolating the unwanted radiation, in microstrip patch antennas for improving the performance of these antennas and in other 5G applications. The analysis and design of the double concentric ring frequency selective surface (DCRFSS) is presented in this research. In the sub-6 GHz 5G FR1 spectrum, a computational synthesis technique for creating DCRFSS based spatial filters is proposed. The analytical tools presented in this study can be used to gain a better understanding of filtering processes and for constructing the spatial filters. Variation of the loop sizes, angles of incidence, and polarization of the concentric rings are the factors which influence the transmission coefficient as per the thorough investigation performed in this paper. A novel synthesis approach based on mathematical equations that may be used to determine the physical parameters of DCRFSS-based spatial filters is presented. The proposed synthesis technique is validated by comparing results from high frequency structure simulator (HFSS), Ansys electronic desktop circuit editor, and an experimental setup. Furthermore, the findings acquired from a unit cell are expanded to a 2 × 2 array, which shows identical performance and therefore proves its stability.     

Application of dual-mode filter techniques to the broadband matching of microstrip patch antennas

Structures such as square or circular microstrip patch antennas may support two orthogonal resonant modes. The paper presents a new method of utilising the dual-mode property to increase the bandwidth of microstrip antennas. The input impedance of such a dual-mode antenna may be represented as a second-order ladder network of coupled resonators, where each resonator is coupled to a load resistor. A theoretical method for evaluating the coupling values in the network is presented, enabling the bandwidth of a dual-mode antenna to be maximised. A theoretical bandwidth improvement of up to 3:1 is achieved when compared to a single-mode antenna. This is confirmed with an experimental dual-mode circular microstrip patch antenna     

Design of a microstrip filter using multiple capacitively loaded coupled lines

A method to design a microstrip filter has been proposed. The multiple capacitively loaded coupled lines are adopted for the design of the microstrip filter. The filter shows different stopband behaviour with respect to even or odd total number of resonators. The transmission zeros may be located around the lower, higher or both regions of the passband's skirt. The coupling among the capacitively loaded lines can produce another transmission zero particularly in the higher stopband. A bandpass filter and a duplexer utilising these features are designed. The equivalent model is also proposed to illustrate the filter's coupling among these capacitively loaded coupled lines. The design has been verified by experimental results     

环形波导微波场分布的计算

提出了环形波导场分布的计算模型 ,计算了环形波导内的微波场分布。结果表明即使在环形腔直径大于微波波长时 ,微波能量也能传到真空室中心附近 ,这为实现大面积均匀等离子体提供了理论依据