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.     

CPW-fed ultra wideband slot antenna with arc-shaped stub

An ultra wideband coplanar waveguide (CPW) fed slot antenna is presented. A rectangular slot antenna is excited by a 50-CPW with an arc-shaped tuning stub. For the proposed antenna, the 210 dB return loss bandwidth could reach 15.6 GHz (3.7-19.3 GHz), which is about 135% with respect to the centre frequency of 11.5 GHz. Details of the antenna design, simulation and measured results on the return loss and the E-and H-plane radiation patterns of the proposed antenna are presented.     

Compact wideband antenna for wireless communications

A compact dual-band printed wire antenna for applications in wireless communications is presented. An additional shorted parasitic element to the F-shaped wire antenna is introduced to achieve a dual-band operation. As an example, a new antenna was designed and fabricated for wireless local area network applications that operate in the 2.4 and 5.2/5.8 GHz bands. The prototyped antenna offered two separate measured impedance bandwidths of 700 (2.35-3.05 GHz) and 2150 MHz (3.95-6.1 GHz), for a return loss less than -10 dB. A measured antenna gain of 1.78-1.9 dBi was observed across the lower band, whereas a measured antenna gain of 3.9-4.4 dBi was observed across the upper band. The measured radiation patterns were stable across the passband     

Ultra wideband vertical microstrip?microstrip transition

Simple design guidelines for an ultra wideband aperture-coupled vertical microstrip-microstrip transition are presented. The proposed transition uses broadside coupling between elliptical-shaped microstrip patches at the top and bottom layers via an elliptical-shaped slot in the mid-layer. Theoretical analysis indicates that the best performance concerning the insertion loss and the return loss over the maximum possible bandwidth can be achieved when the between the top and bottom coupled patches is equal to 0.8 (or 1.94 dB). Simulated and measured results show that the proposed transition has an insertion loss of <0.7 dB and a return loss of >15 dB across the frequency band 3.1-10.6 GHz.     

Design and optimisation of a high-frequency EMC wideband horn antenna

A new approach for the design of high-frequency electromagnetic compatibility (EMC) broadband double-ridged horn (DRH) antennas is presented. In this approach, first a conventional DRH antenna at 1-18 GHz frequency band is considered. Using a thorough sensitivity analysis of different structural parameters of the 1-18 GHz DRH antenna, several modifications are applied to this antenna to overcome its deficiencies especially in its radiation pattern at higher frequencies. The final achieved design is then scaled up in the frequency to arrive at a design suitable for higher frequency ranges. A wideband DRH antenna for 18-40 GHz frequency band is then designed using this approach. The lower frequency ratio of 1:2.2 in the new antenna as opposed to the 1:18 ratio in the conventional antenna permits us to choose the best frequency window for the scaling up process. Besides, an optimisation technique is employed to further improve the antenna performance to meet the design goals over the entire new frequency band, that is, to have a single main lobe directed along the horn axis without any deterioration, and to have acceptable broadband gain with the minimum of 10 dB, and voltage standing wave ratio (VSWR) of less than 1.5. The final design which is more compact compared with the other commercial antennas has been used to make a prototype antenna. Measurements show that the built prototype meets the design goals very well     

A wideband coplanar waveguide-fed circularly polarised antenna

A wideband coplanar waveguide (CPW)-fed circularly polarised antenna is presented. It contains two loops arranged in an unusual way. One unique feature is that the positive signal line of the CPW is split into one vertical and one horizontal arm after a simple match. Another large surrounding open ring is used to suppress the surface wave. The antenna has more than 20% 10 dB return loss and 3 dB axial ratio bandwidth.     

Compact wideband Koch fractal printed slot antenna

A compact wideband printed slot antenna, suitable for wireless local area network (WLAN) and satisfying the worldwide interoperability for microwave access (WiMAX) applications, is proposed here. The antenna is microstrip-fed and its structure is based on Koch fractal geometry where the resonance frequency of a conventional triangular slot antenna is lowered by applying Koch iterations. The antenna size inclusive of the ground plane is compact and has a wide operating bandwidth. The proposed second iteration Koch slot antenna operates from 2.33 to 6.19 GHz covering the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands. The antenna exhibits omnidirectional radiation coverage with a gain better than 2.0 dBi in the entire operating band. Design equations for the proposed antenna are developed and their validity is confirmed on different substrates and for different slot sizes.     

Ultra wideband inphase power divider for multilayer technology

A multilayer inphase power divider with an ultra wideband behaviour is presented. The proposed divider exploits broadside coupling via a multilayer microstrip/slot configuration. The design method utilised for the device is based on the conformal mapping techniques. The developed device has a compact size with an overall dimension of 20 mm x 30 mm. The simulated and measured results show that the proposed device has equal power division between the two output ports with <0.2 dB amplitude imbalance between them, better than 10 dB return loss and isolation and < 2degrees phase difference between the two output signals across the frequency band 3.1-10.6 GHz.     

Ultra wideband technologies coexistence in Nakagami-m fading channels

The wide spectrum of ultra wideband (UWB) communications makes it inevitable to consider strategies for avoiding and mitigating interference from narrowband wireless systems such as GPS, UMTS, and WLAN, or other UWB wireless technologies. In this paper, we provide a performance analysis of multiband orthogonal frequency division multiplexing (MB-OFDM) UWB in the presence of binary phase-shift keying time-hopping (BPSK-TH) UWB or BPSK-DS UWB interfering transmissions under Nakagami-m fading. In the bit-error rate (BER) analysis, several UWB interferers are considered to affect the MB-OFDM signal. A Gaussian approximation is considered for the UWB interferers and used in the analysis of the BER performance of the MB-OFDM UWB system. The Nakagami-m distribution is applied to characterise the amplitude of the fading channels for both the reference signal and the interference signals. Furthermore, a waveforming technique is considered for mitigating the effect of interference and its efficiency is illustrated in terms of BER improvement. Numerical and simulation results are provided and compared for different coexistence scenarios.     

Design of square patch antenna with a notch on FR4 substrate

Simulation and measured results of a square patch antenna with a notch to search their possible application on modern communication systems including WiMax systems are presented. The antennas are designed on an FR4 substrate and the notch angle is varied under different conditions. It is found that on varying the notch angle from 180° to 164°, antennas resonate at a single frequency but on reducing the notch angle further, antennas start resonating at two frequencies with improved bandwidth. The optimum performance of an antenna is obtained when the notch angle is set to 151°. Different radiation parameters of the antennas under varying conditions are analysed and their possible applications in modern communication systems are investigated.     

Ultra wideband powerline communication (PLC) above 30 MHz

A novel study of ultra wideband (UWB) communication over the indoor powerline channel, in a wide frequency range up to 1 GHz is presented. An exhaustive measurement campaign was conducted on a test bed that replicated the environment of an indoor powerline network. The aim of this study was to observe and analyse the transmission and noise properties of such a broadband powerline channel. A time domain channel model has been used to study the broadband channel response of the powerline. Measurement and modelling results show that the indoor powerline channel provides a communication link in the 50-550 MHz frequency range. Channel capacity is greatly enhanced by exploiting the 500 MHz bandwidth. The conclusions of this study indicate that gigabit per second data rate transmission are possible over the indoor powerline channel in 50-550 MHz.     

Inkjet-printed patch antenna emitter for wireless communication application

This research focuses on exploring low-cost and rapid production solutions for fabricating emitters for patch antennas for wireless communication applications. Additive manufacturing technique is employed to fabricate two patch antennas using silver nanoparticle ink on FR4 substrate. Finite-element simulation software, HFSS is used to analyse and predict the theoretical performance of the antenna designs for 2.4?GHz MIMO and 6?GHz wireless data transmission. The fabricated antennas have resonant frequencies closely matching the design values. The work provides a viable solution for fabricating emitters and finally antennas commercially using inkjet printing platform, thus overall reducing the cost and simplifying the process.     

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.     

A range profiling technique for synthetic wideband radar

A technique is proposed for reconstructing wide range profiles using stepped-frequency waveforms (SWFs). The technique is based on reconstructing range sub-profiles. With respect to previous methods, the proposed technique can be applied to any kind of SWFs. Moreover, for a given range resolution, long range profiles can be formed without increasing the number of transmitted frequencies. Theoretical results are also derived that provide a correct setting of waveform and processing parameter. Finally, as case studies, the proposed method is applied to three SFWs, namely short-pulse stepped-frequency, linear frequency modulated stepped frequency and phase-coded stepped-frequency waveforms. Simulations prove the effectiveness of the proposed range profile reconstruction.     

Investigation of anisotropic negative permeability medium cover for patch antenna

A more directional and higher gain patch antenna with an anisotropic negative permeability medium (NPM) cover is proposed. The patch antenna operates at the frequency where the permeability of split-ring resonator (SRR) is negative, and then the sideward radiation can be forbidden. It leads to a significant enhancement of designing the high gain antenna. We investigate numerically and experimentally the performance of the antenna when NPM composed of SRR is placed above the patch antenna. The measured result has a good agreement with the simulation. Compared with the conventional antenna, the result shows that the beam of antenna with the NPM cover becomes more convergent, half-power beamwidth is smaller by almost 30deg in the H-plane and 10deg in the E-plane and the gain is higher by 4.03 dB. Moreover, NPM cover can have applications in the other types of antenna such as monopoles, dipole antennas, leak-wave antennas and aperture antennas.     

Wideband microstrip patch antenna design for breast cancer tumour detection

A patch antenna is presented which has been designed to radiate frequencies in the range 4-9.5 GHz into human breast tissue. The antenna is shown by means of previously unpublished simulation and practical measurements to possess a wide input bandwidth, radiation patterns that remain largely consistent over the band of interest and a good front-to-back ratio. Consideration is also given to the antenna's ability to radiate a pulse, and in this respect it is also found to be suitable for the proposed application     

Design of fractal patch antenna for size and radar cross-section reduction

This research study presents a novel design of star-shaped fractal patch antenna for miniaturisation and backscattering radar cross-section (RCS) reduction. The proposed fractal antenna gives 50% size reduction compared with a conventional circular microstrip patch (CCMP) antenna. The antenna is studied experimentally for return loss behaviour using vector network analyser R&S ZVA40. It can be useful for wireless application in 0.85-4 GHz frequency band. Further, the study focuses on backscattering RCS (both monostatic and bistatic) reduction by the proposed antenna compared with the CCMP antenna. It is found that increase in number of fractal iterations included in the conventional patch to design fractal antenna geometry reduces backscattering RCS at multiband compared to the conventional patch antenna. This reduction in backscattering RCS by the antenna is observed at multiband. The antenna can be tuned for low backscattering by variation in the substrate dielectric constant and thickness and the superstrate dielectric constant and thickness. For maximum RCS reduction by the antenna, optimisation of substrate thickness becomes necessary. The study also deals with effect of frequency and aspect angle variation on backscattering RCS reduction.     

An approach to expansion of the scanning sector of active phased antenna arrays with linear-frequency-modulated wideband probe signal

The process of construction of the directional pattern of active phased antenna arrays with emission of wideband linear-frequency-modulated signals is analyzed. Factors responsible for the appearance of distortions in the directional pattern are established and an approach to elimination of these distortions is proposed.