In this paper, a three-dimensional (3-D) low-loss and wideband BPF based on lowtemperature co-fired ceramic (LTCC) has been presented for 60 GHz wireless communication applications. Via pads in the vertical via transitions are designed as an additional resonator for lowloss and wide-bandwidth of the BPF. The proposed BPF has been designed by investigating its characteristics as a function of dimensions of the resonators such as a single-mode patch and via pads and also a length of feed lines are optimized for effective coupling. The designed BPF was fabricated in a 6-layer LTCC dielectric. The fabricated BPF shows a centre frequency (fc) of 61.46 GHz and a 3dB bandwidth of 10.5% from 58.2 to 64.7 GHz (6.47 GHz). An insertion loss of -2.88 dB at fc and return losses below -10 dB are achieved. Its whole size is 4.72 × 1.7 × 0.684 mm3.
Interaction of an electromagnetic wave and an inhomogenous plasma slab with electron distribution in the form of partially linear and sinusoidal profiles is analysed to determine new reflection, absorbtion and transmission characteristics. Broadband and tunable absorbtion performance of the plasma layer accompanied with narrowband reflection characteristics is presented as the function of electron density profile parameters and external magnetic field excitation. According to the resulting performance characteristics, proposed plasma layer is found to be useful as a new absorbing layer for shielding and stealth applications.
Delay lines come in varying topologies such as the simple meander line or the spiral delay lines. The major characteristic of these delay lines is their introduction of a laddering behavior at the output. Such laddering behavior can render the predictability of the delay very difficult unless time-consuming full-wave simulation is used. In previous works, delay lines were considered with minimal attention to the effect of the loss tangent. In this paper we have studied the effect of loss- tangent on the laddering behavior in delay lines and found that by considering the loss-tangent of the dielectric of the host medium, the laddering behavior is no longer present, thus eliminating the possibility of over- or under shooting logic levels at the output.
An ultra-wideband hexagonal ring antenna with dual tunable band-notches is presented in this paper. The proposed antenna achieves a good impedance match (VSWR≤2) covering the range of 2.5-10.6 GHz, except for the bandwidths of 3.1-3.8 GHz for WiMAX and 5.15-6 GHz for WLAN. The band-notch function is evolved by a stub and two pairs of parasitic elements for WiMAX and WLAN, respectively. The experimental results show that the band-notched characteristics can be tuned by adjusting the lengths of the stub and the two pairs of parasitic elements.
In this work, we analyse the frequency response of microstrip lines coupled by complementary split ring resonators (CSRRs) etched on the ground plane supporting electroinductive waves (EIWs). The single-particle configurations demonstrate the principle of operation whose bandwidths reach 67% of the central frequency. A double configuration is afterwards investigated as a further improvement of the filtering response, such as the level of the spurious lower frequency band. Finally, an ultimate prototype comprising different CSRRs along the access line, together with the aforementioned EIW-coupling is proposed for filtering undesired higher bands. Experimental results confirm numerical analysis.
In this paper, the potential use of split ring resonators (SRRs) to design very compact dual-band bandstop waveguide filters is proposed. Two square SRRs are placed on a same transverse plane realizing two independent reject bands. By adjusting the SRRs length, the stopbands can be targeted at the desired frequencies. In addition, a simple circuit model for this resonator is introduced. Good agreement between the experimental and full-wave simulated results has been achieved.
A wideband rod-dipole antenna with a modified feed for DTV signal reception in the 470-862-MHz UHF band is presented. The antenna consists of two retractable rod-dipole arms, which are connected to the opposite top corners of the modified feed. The feed is in the shape of a rectangle with dimensions 20 mm × 40 mm and divided into two portions by a U slit. The antenna can generate nearby resonant modes to attain a wide operating band, exceeding 60% bandwidth with VSWR below 3, much larger than that of the conventional center-fed dipole antenna. In addition, with the two dipole arms designed at the production stage to be able to swivel around, the antenna radiation and polarization thereof can easily be adjusted for better DTV signal reception without moving the whole antenna structure.
A wideband unidirectional antenna composed of a magneto-electric dipole with Γ-shaped feed is designed. Simulated and measured results are presented. It achieves an impedance bandwidth of 84% for VSWR ≤ 2 ranging from 2.05GHz to 5.05GHz, stable peak gain of around 5 dBi, unidirectional radiation patterns and low cross polarization over the whole operating band. It is sufficient for accommodating recent wireless communication services such as 3G, WiFi, WiMax, Bluetooth, WLAN and Zigbee, etc.
A novel compact balun (balanced-to-unbalanced) that consists of a low-pass network served by a microstrip electromagnetic bandgap (EBG) cell and a high-pass π-network formed with an interdigital capacitor is presented. This proposed approach can effectively operate the compact balun without the use of λ/4 microstrip lines to reduce the circuit area over 50% compared to the conventional Marchand balun. The core dimension of the compact balun is 0.74 cm x 0.7 cm. The planar structure enables an efficient circuit design in printed circuit boards (PCB) without using any bonding wires, defected ground structures (DGS), or surface mounted devices (SMD). A compact balun operating in the 3 GHz band has been implemented in a FR-4 PCB. From the measured results, the return loss of the input port is better than 15 dB over the band from 2.6 to 4 GHz. The amplitude and phase imbalances are less than 1.4 dB and 3° with the 20% operational bandwidth ranging from 2.7 to 3.3 GHz, respectively.
In this paper, a wideband planar dipole antenna is proposed. Compared to conventional dipole antennas, this antenna has wideband impedance matching, simple structure and compact size. From EM simulations, dimensions of antennas are chosen for better performance. For verification, this newly proposed structure is fabricated and measured. It is shown that return loss of the antenna between 2.5 GHz and 8.0 GHz is better than -10 dB.
In this paper, the authors present an optimization method based on modified Particle Swarm Optimization (PSO) algorithm for thinning large multiple concentric circular ring arrays of uniformly excited isotropic antennas that will generate a pencil beam in the vertical plane with minimum relative side lobe level (SLL). Two different cases have been studied, one with fixed uniform inter-element spacing and another with optimum uniform inter-element spacing. In both the cases, the number of switched off elements is made equal to 220 or more. The half-power beam width of the synthesized pattern is attempted to make equal to that of a fully populated array with uniform spacing of 0.5 λ. Simulation results of the proposed thinned arrays are compared with a fully populated array to illustrate the effectiveness of our proposed method.
The phase of the reflection coefficient of a TE10 rectangular waveguide mode at the cut-off point in a gentle downtaper is investigated through both experiment and computer simulation. The result shows a very good agreement with the theoretical prediction based on the work by Katsenelenbaum et al., that is, a +90° phase shift occurs at the cut-off point for TE modes if the cut-off point is not too close to the end of the downtaper. An application for the determination of the resonant frequencies for the spurious trapped TE30 mode in an uptaper-downtaper oversized resonant structure is presented.
In this paper, we present a modified semi-elliptical monopole antenna with a two-branch feed line and dual band-notched filter structure for UWB applications. By adjusting the parameters of the proposed antenna an UWB impedance bandwidth with a very good impedance matching can be achieved. The designed antenna has a small size of 20 mm × 20 mm and operates over the frequency band between 2.7 to 11 GHz, rejecting the undesired frequency bands from 3.3 to 3.8 GHz and 5.1 to 5.85 GHz.
A four-pole elliptic function compact bandpass filter is designed by using interdigital hairpin resonator and step-impedance hairpin resonator. The miniaturized band-pass filter is also implemented using high permittivity dielectric substrate. The full-wave simulator IE3D is used to design the compact hairpin resonator, and to calculate the coupling coefficient of the basic coupling strictures. The responses of the fabricated filters using Al2O3(εr = 9.7, Q×f = 350000 GHz) and 0.6Sm(Co1/2Ti1/2)O3-0.4CaTiO3 (εr=37, Q×f = 43000 GHz) dielectric substrates are designed at a center frequency of 2 GHz. The size of the compact hairpin filter using 0.6Sm(Co1/2Ti1/2)O3-0.4CaTiO3 ceramic substrate, as compared to that of a compact hairpin filter using Al2O3 ceramic substrate, is reduced in size by 45%. The compact size and good agreement have been obtained between simulations and implementation results.
A compact ultra-wideband (UWB) planar monopole antenna is proposed. Multiple trapezoids and a semicircle are connected to form the patch of the monopole. The compact antenna not only has low return loss, but also has omni-directional radiation pattern over the ultra-wide bandwidth. Both the simulated and measured results are given and they are in reasonable agreement. The group delay, which is an indication of linearity between two proposed antennas, is also good. Parametric analysis on the patch shape has been performed to give some helpful design information.
A novel Competitive Algorithm of Simulating Natural Tree Growth is presented in this paper. It searches from a simple status to complex ones and is characterized by quick convergence. The algorithm has been used to design a novel tree-shaped antenna which has an appreciably larger gain of 2\,dBi more than traditional dipole antenna with a reflector of the same size. A prototype antenna has been fabricated and tested. A good agreement between the calculated and measured results verifies the feasibility of the algorithm.
In this paper, a method to broaden the beamwidths of a crossed dipole antenna is proposed. By introducing four parasitic strips around the crossed dipole antenna, the beamwidths of the crossed dipole antenna in the vertical plane are broadened effectively, making the patterns uniform over a wide frequency band. An L-band prototype, operating in the frequency range from 1.1 GHz to 1.6 GHz, is fabricated and tested. The simulated and measured results show that the beamwidths at lower frequencies are broadened and uniform radiation patterns over the whole operating frequency band are obtained, making the crossed dipole suitable for wideband marine GPS (Global Positioning System) applications.
In this work, the efficient analysis and design of optimised turnstile junctions showing low reflection coefficient is investigated. For this purpose, a rigorous multimodal analysis of compensated junctions is developed, which is based on the computationally efficient 3-D Boundary Integral-Resonant Mode Expansion (3-D BI-RME) technique. The electrical performance of the standard turnstile junction has been drastically improved by compensating this microwave component using piled-up partial-height cylindrical metallic posts placed on the base of the junction. Moreover, the authors demonstrate that improved designs can be derived by compensating the turnstile junction using one single cylindrical post, which is easier to manufacture than a piled-up post, and it is a more robust element to confront high-power effects. This novel Computer-Aided Design (CAD) tool has been verified through excellent comparisons between the obtained results and those provided by the technical literature, and also by a well-known commercial finite-element method software.
This paper presents a novel spurious suppressed bandpass filter designed with triangular stepped-impedance resonators. The proposed resonators are folded for a triangular schematic, which creates two transmission zeros. By varying the line width of resonators, one of the zeros is tuned to suppress the first and second spurious responses, and the other is used to improve skirt selectivity. The current study analytically derives explicit design equations and fabricates a three-pole Chebyshev bandpass filter centered at 1.5 GHz based on the direct-coupled structure. The experimental results show spurious suppression improvement more than 20 dB up to 5.6 f0.
In this work, a polarisation agile antenna based on an array of two injection locked oscillators is presented. The proposed topology provides a theoretical relative phase shift range of 360 degrees between the output signals, which can be easily controlled through two DC voltages. The behaviour of the system is studied, both through simulations and measurements of the manufactured prototype, focusing on the joint performance of the oscillators. The data transmission capabilities of the system are analysed, proposing a solution for phase modulated signals.