In this paper, a novel compact ring resonator based bandpass filter with a second harmonic rejection capability is proposed. The proposed bandpass filter uses a stepped-impedance open stubs and a stepped-impedance ring resonator at feeding lines. Stepped-impedance open stubs are used to obtain a better rejection level in the second harmonic-frequency band. Ring resonator's radius is calculated by examining and solving the eigenvalue equation of the ring resonator. Firstly, Sierpinski second order curve is used to achieve size reduction of about 66 % and 71 % compared to conventional microstrip ring bandpass filter inner and outer areas, respectively. Sierpinski curve is chosen because of its symmetry and its suitability for orthogonal feeding lines and open stubs incorporation without using any additional space. Referring to resonant rejection value, the proposed first Sierpinski structure -15 dB simulated fractional bandwidth is 5.6 % at 1.505 GHz and with rejection of -0.16 dB. Transmission zeros at 2.25 GHz and 3.78 GHz are obtained. Secondly, stepped-impedance open stubs are added to the resonator ports to add another transmission zero at 3.84 GHz. At 2.9 GHz, second harmonic band, the proposed structure achieves rejection of - 6.7 dB instead of -1.7 dB for the conventional one. The proposed structure -15 dB simulated fractional bandwidth is 3 % at 1.42 GHz. Innovation is achieved by the simplicity of inserting the transmission zeros, controlling zeros rejection values, incorporating stubs and orthogonal feeding lines in the same resonator area and reasonable power capability of the proposed structure. The proposed bandpass filter's prototype is fabricated using FR4 material, and a good agreement is found between simulated and measured results for return loss and rejection values. The proposed structure is very suitable for L-band applications.
A circular slotted elliptical patch antenna with an elliptical notch in ground for L-band and S-band application is presented. The proposed antenna consists of an elliptical patch with a circular notch on the top layer of a substrate, and a wide elliptical slot and an elliptical notch with two symmetrical slots on the bottom layer of the same substrate. The proposed antenna was fabricated on an FR-4 substrate (tan(δ) = 0.02, εr = 4.3) with the thickness of 1.6 mm, and it was excited by coaxial feed joined with microstrip line through via. The proposed antenna exhibited the bandwidth of 110.28% from 1.2 GHz to 4.15 GHz for |S11|. Surface current distribution and radiation pattern at resonating frequencies 1.71, 2.28, 3.03 and 3.84 GHz were analyzed. Evolution of the antenna and effect of parameters were also studied to know the behavior of the antenna.
Artificial magnetic conductor (AMC) is a periodic structure with in-phase reflection, which can be used in dual-polarization dipole antenna to reduce profile height. In this study, a low-profile dual-polarized dipole antenna with an AMC reflector is proposed by improving the AMC structure. The antenna consists of a pair of orthogonal planar dipoles with U-shaped slots, two T-shaped feeding lines, and an AMC reflector. The overall height is 0.132λ2.2 GHz. Experimental results show that the proposed antenna has a wider bandwidth than other antennas of the same type. The impedance bandwidth of this antenna is 52.3% (1.65 GHz to 2.81 GHz), and the proposed antenna also has the advantages of low profile, high port isolation (<-30 dB), and low cross polarization (<-27 dB). These features can meet the current needs of the telecommunications industry.
In this communication, a dual-sense dual-polarized hybrid rectangular dielectric resonator antenna (RDRA) is explored. Two leading aims of the present article include: (i) to obtain dual-polarization characteristics i.e. the combination of linear and circular polarizations; (ii) to achieve quad-band features by using the concept of hybrid antenna. Modified printed line is used to excite dual radiating modes in RDRA i.e. TExδ11 and TEy1δ1. In order to authenticate the proposed radiator, archetype of the proposed antenna is fabricated and tested. Good accord is established between measured and simulated outcomes. The proposed radiator is operated over four different frequency bands i.e. 1.81 GHz-2.06 GHz, 2.37 GHz --2.7 GHz, 3.35 GHz -- 4.4 GHz, and 4.62 GHz -- 5.62 GHz. Left Hand Circularly Polarized (LHCP) and Right Hand Circularly Polarized (RHCP) waves are obtained form 4.1-4.39 GHz and 4.78-5.2 GHz respectively. All these properties of the proposed radiator make it appropriate for 3G/WLAN/WiMAX applications.
A highly efficient Doherty power amplifier (DPA) using shunted reactive load is designed to achieve wideband operation. For enhanced back-off efficiency over the whole bandwidth, a modified load modulation network (LMN), which employs a shunted reactive load at the combining point, was firstly designed to enlarge the effective load impedance of the carrier amplifier at low and high frequencies. Then, the two-point matching approach was employed to design the carrier and peaking output matching networks, which can eliminate the use of offset lines and simplify the LMN. Measurement results show that the designed DPA can deliver an efficiency of 48%-61% at 6 dB back-off power over the frequency band of 2.2-2.9 GHz. For a 20 MHz LTE modulated signal, an average efficiency of higher than 55% can be achieved at an average output power of 37 dBm, while the adjacent channel leakage ratio is below -49 dBc after linearization.
A broadband circularly polarized cross-shaped slot antenna with a parasitic cross-shaped patch and an improved feedline is proposed for wireless applications between 3-6 GHz. In order to achieve a wide axial ratio bandwidth that is totally enclosed within a wide impedance bandwidth, a wide cross slot in the ground plane and an L-shaped strip attached to the lower section of the feedline are employed. This design presents a technique for achieving an axial ratio (AR) bandwidth for a single fed antenna that is wider than most of the single fed slot antennas that currently exist. The proposed antenna with a compact size of 30 mm × 30 mm × 1.6 mm is fabricated and measured. A measured broadside 3 dB axial ratio bandwidth of 68.7% (3.1-6.35 GHz) within a measured impedance bandwidth of 84.1% (2.61-6.4 GHz) for S11 < -10 dB is obtained. A measured peak gain of 3.8 dBi is obtained within the axial ratio bandwidth. The obtained results show that the antenna can be used for wireless devices that operate in the 3.3-3.8 GHz and 5.15-5.35/5.725-5.825 GHz (specified by IEEE 802.11a) bands for wireless standard technologies.
A novel rat-race coupler with wide adjustable range of power-dividing ratio and uncrossed input/output ports is presented by using coupling adjustable trans-directional (TRD) coupled lines, parallel coupled lines and a 180° phase shifting line. Wide adjustable range of power-dividing ratios is accomplished by varying the coupling of the TRD coupled lines. Moreover, with the combination of the TRD coupled lines and parallel coupled lines, the input and output ports of the rat-race coupler are uncrossed. The structure of the proposed rat-race coupler is analyzed, and the design equations are derived. As an example to validate the feature of the proposed rat-race coupler, a prototype operating at 1.6 GHz is devised, fabricated and measured. The measured results show that the designed coupler has a wide adjustable range (-7 ~ 15 dB) of power dividing ratio with a controlled voltage range of 3.5 to 13.5 V.
This paper studies the application of vortex wave with orbital angular momentum (OAM) in the radar. The vortex waves can have eigenstates or modes with different integer topological charges, which are orthogonal to each other. The eigenstates with topological charges of 0, -1 and 1 were utilized in this paper. The radar transmitted the pulse with topological charge of 0 and received echoes with topological charges of 0, -1 and 1. The receiver can process the signals received by these orthogonal modes to obtain the azimuth and elevation angles of the two targets in a same range gate. Compared with the traditional mono-pulse radar only with sum beam and difference beam, this vortex-wave-based radar can track two targets in principle. This is meaningful for the application of the vortex wave.
Digital manufacturing, or 3D printing, is a rapidly emerging technology that enables novel designs that incorporate complex geometries and even multiple materials. In electromagnetics and circuits, 3D printing allows the dielectrics to take on new and profound functionality. This paper introduces negative uniaxial metamaterials (NUMs) which are birefringent structures that can be used to manipulate electromagnetic fields at a very small scale. The NUMs presented here are composed of alternating layers of two different dielectrics. The physics of the NUMs are explained and simple analytical equations for the effective dielectric tensor are derived. Using these equations, the NUMs are optimized for strength of anisotropy and for space stretching derived from transformation optics. The analytical equations are validated through rigorous simulations and by laboratory measurements. Three NUMs where manufactured using 3D printing where each exhibited anisotropy in a different orientation for measurement purposes. All of the data from the analytical equations, simulations, and experiments are in excellent agreement confirming that the physics of the NUMs is well understood and that NUMs can be designed quickly and easily using just the analytical equations.
A novel design for radar cross section (RCS) reduction of a bilateral Vivaldi antenna is presented. The method for RCS reduction is based on the wave-guiding characteristic of the substrate integrated waveguide (SIW) structure, which guides the incident energy to the lateral side of antenna plane. The bistatic RCS is controlled under the premise of reducing the monostatic RCS. Compared with the reference antenna, a significant monostatic RCS reduction is achieved over a wide frequency band ranging from 5 GHz to 12 GHz, and a remarkable monostatic RCS reduction at 7 GHz is as much as 34.73 dB without obvious radiation performance degradation. To verify the proposed strategy, prototypes of the reference and proposed antennas have been fabricated and measured. Good agreements between the simulated and measured results demonstrate that the proposed method preserves the radiation performances well and achieves an outstanding wideband RCS reduction.
A novel broadband circularly polarized planar monopole antenna fed by coplanar waveguide (CPW) is proposed and fabricated. The proposed antenna consists of a rectangular monopole, an inverted-L strip and an asymmetric ground plane with cutting a horizontal slit on the right ground plane. Firstly, a narrow circularly polarized (CP) radiation at the upper band can be achieved by utilizing the asymmetric ground plane. Then, an inverted-L strip is introduced to obtain broadband CP characteristic matched with wide impedance bandwidth. The measured results demonstrate that a 10-dB bandwidth of 58.8% from 4.8 to 8.8 GHz and a 3-dB axial-ratio bandwidth (ARBW) of 47.8% from 5.375 to 8.75 GHz can be achieved which can completely cover the WLAN (5.725-5.85 GHz) band. Additionally, a 10-dB impedance bandwidth of 24% (3.3-4.2 GHz) with linear polarization is also obtained which can completely cover the WiMAX (3.3-3.7 GHz) bands. In additional, to explain the mechanism of dual-band CP operation, the analysis of magnetic fields distributions and a parametric study of the design are given. Compared to other recent works, a simpler structure, wider axial ratio and impedance bandwidths and a more compact size are the key features of the proposed antenna.
A novel Yagi-Uda-like transmitarray is proposed for circularly polarized (CP) operation. The element consists of multiple strips stacked in parallel for achieving broad transmission phase range. By employing the design concept for the Yagi-Uda director, the transmitarray elements are made to provide the functions of phase shifter and director simultaneously. By introducing rotational offset into the stacking strips, the element is found to be able to generate circular polarization. To demonstrate the working principle, an 8-layer unit element is simulated using the Floquet method to provide a transmission phase range of 412˚. The proposed 5×5 full-fledged CP transmitarray is able to produce an antenna gain of 16.2 dBi, a -1-dB bandwidth of 4%, an axial-ratio bandwidth of 7%, and an aperture efficiency of 40.4%. A simple curve-fitted design equation is also given.
A S-band monolithic integrated switched filter bank has been designed to realize tunable working center frequency, and a tuning range of 12.9% from 2.7 to 3.05 GHz was achieved with interval of 50 MHz. The switched filter bank is designed using 8 eighth-order step impedance resonators (SIR) band-pass filters arranged in parallel rows. Microelectromechanical Systems (MEMS) switched circuit is integrated above filters for monolithic design combined with low temperature co-fired ceramic (LTCC) technology. The SIR bandpass filters are designed to resist Electromagnetic Interference(EMI) between components and introduce cross coupling to bring two transmission zeros and better out-of-band rejection. The monolithic integrated switched filter bank is only 74 mm×24 mm×2.5 mm, which realizes the monolithic integration of the device and enhances the reliability. The measured results show that the insertion loss and out-of-band rejection are in good working condition.
In this paper, a novel bandwidth-enhanced ultra-wideband (UWB) tapered slot antenna, with Y-shaped corrugated edges, is proposed. In the double-slot structure, the two slots are separated by a V-shaped metal surface with straight edges, which is beneficial for improving the directivity of the antenna. Meanwhile, an exponential Y-shaped corrugated edge is designed. This novel corrugated edge not only can improve the impedance bandwidth of the antenna by extending the path of the current, but also can enhance the directivity by concentrating the energy near the tapered slot. The proposed antenna provides 167% fractional bandwidth from 2.5 GHz to 28 GHz. The gain of the antenna is more than 10 dB from 3.5 GHz to 25 GHz and more than 8 dB in the whole operating band.
In this paper, a lowpass filter with -3 dB cutoff frequency of 5.3 GHz using T-shaped and polygon resonators is presented. The applied resonators create a sharp transition band of 0.2 GHz from -3 dB to -40 dB. To obtain an ultra-wide stopband about 54 GHz (10.18fc) with a suppressing level of -21 dB, two different suppressing cells are employed. The overall circuit size is 59.16 mm2, which indicates a small occupied area. To clarify the performance of each resonator and describe the location of the transition zeros, exact equations based on the equivalent LC circuits have been calculated.
A simple dual-port sum-difference beam antenna with high isolation is proposed. A T-shaped slot is utilized to achieve both sum-difference beam pattern and high port-isolation. The slot coupling feeding structure simplifies the feeding network and avoids complicated fabrication. The proposed antenna is simulated, fabricated and measured. Experimental validations confirm that the antenna has 10-dB impedance bandwidths of 10.2% (4.82-5.33 GHz) for the sum port and 2.0% (4.95-5.05 GHz) for the difference port, respectively. In addition, high port-isolation better than 50dB is achieved covering a wide band from 4.0 GHz to 5.5 GHz. The proposed antenna exhibits a measured peak gain of 6.3 dBi for the sum beam and a null depth better than -26 dB for the difference beam. Measured results agree well with simulated ones.
This paper presents a Ka-band 4-bit BiCMOS digital step attenuator with maximum attenuation of 7.5 dB (16 states). The proposed attenuator design is based on switched T-bridge network including phase correction network and is fabricated in 0.13 μm SiGe BiCMOS technology. Attenuator with phase correction structure shows root mean square (RMS) amplitude errors <0.8 dB at 31 to 33 GHz and the RMS insertion phase varying from 2.8° to 5.8° over 31-33 GHz. The measured insertion loss is 19 dB and total chip size including pad is 1.92×0.4 mm2.
In this paper, a CPW-fed circular patch UWB-extended bandwidth antenna is proposed which is fabricated and characterized on silicon. The proposed antenna covers fractional bandwidth of 132.08% with high rejection triple band-notch characteristics [WiMAX(3.30 GHz-3.80 GHz)/WLAN(IEEE802.11a/h/j/n 5.15 GHz-5.35 GHz, 5.25 GHz-5.35 GHz, 5.47 GHz-5.725 GHz, 5.725 GHz-5.825 GHz)/X-band downlink satellite communication system (7.25 GHz-7.75 GHz)]. Gain and efficiency of the proposed antenna in the entire bandwidth vary between 3.96 dBi-10.98 dBi and 84%-95%, respectively. Also, group delay in the entire operating band is ≤ 1.0 ns. Furthermore, the proposed antenna exhibits good dipole like radiation pattern in E-plane and omnidirectional pattern in H-plane with small dimension of 20×20×0.5 mm3.
Aimed at solving the problems of high initial cutoff frequency, small stopband range and poor inhibition in the current electromagnetic band gap (EBG) structure, an electromagnetic band gap structure designed on the basis of periodic Z-bridge EBG inserted by a double complementary slit ring resonator (DBCSRR) cell is proposed. Compared with the traditional EBG structure, the proposed EBG structure can achieve 270 MHz-20 GHz bandwidth in a reference of -30 dB, which is wide in range. The measured and simulated results indicate the wideband of noise suppression. In addition, the lower and upper cutoff frequencies are estimated by using equivalent circuit models, respectively. Moreover, the IR-Drop and dc resistance is accurately investigated through 3-D simulations. Finally, the transfer characteristics of single signal line are studied.
This paper describes the design and experimental characterization of a circular polarized printed antenna for dual-band WiFi operation at 2.45 GHz and 5.10 GHz. The patch design is based on a combination of slits loading and gap-coupling applied to a disc patch in order to enhance the radiation performances in terms of polarization purity and bandwidth at the two operation frequencies. Experimental validations confirm a maximum gain around 6.0 dB for both 2.45 and 5.10 GHz, as well as an axial ratio as low as 0.5 dB and a return loss exceeding 15 dB on the operating frequencies. These characteristics are suitable for operationing in IEEE802.11x networks.