Showing papers in "IEEE Microwave and Wireless Components Letters in 2005"

Ultra-wideband (UWB) bandpass filters using multiple-mode resonator

Abstract: A novel microstrip-line ultra-wideband (UWB) bandpass filter is proposed and implemented using a multiple-mode resonator (MMR), aiming at transmitting the signals in the whole UWB passband of 3.1-10.6GHz. In the design, the first three resonant frequencies of this MMR are properly adjusted to be placed quasiequally within the UWB. Then, the parallel-coupled lines at the two sides are longitudinally stretched so as to raise the frequency-dispersive coupling degree with the coupling peak near the center of the UWB. After optimization of this filter, a good UWB bandpass behavior with five transmission poles is theoretically realized and experimentally confirmed. Within the whole UWB passband, the return loss is found higher than 10dB, and the group delay variation is less than 0.23ns.

Ultra-wideband bandpass filter with hybrid microstrip/CPW structure

Abstract: A novel ultra-wideband (UWB) bandpass filter (BPF) is presented using the hybrid microstrip and coplanar waveguide (CPW) structure. A CPW nonuniform resonator or multiple-mode resonator (MMR) is constructed to produce its first three resonant modes occurring around the lower end, center, and higher end of the UWB band. Then, a microstrip/CPW surface-to-surface coupled line is formed and modeled to allocate the enhanced coupling peak around the center of this UWB band, i.e., 6.85GHz. As such, a five-pole UWB BPF is built up and realized with the passband covering the entire UWB band (3.1-10.6GHz). A predicted frequency response is finally verified by the experiment. In addition, the designed UWB filter, with a single resonator, only occupies one full-wavelength in length or 16.9mm.

Substrate integrated folded waveguides (SIFW) and filters

Abstract: A substrate integrated folded waveguide (SIFW), integrated transition to shielded stripline and a SIFW filter are demonstrated and shown to be in good agreement with X band measurements. Both the filter and waveguide are considerably smaller than their unfolded counterparts. Furthermore, the filter response is defined purely in terms of a photolithographically etched plane.

Photonic synthesis of broadband microwave arbitrary waveforms applicable to ultra-wideband communication

Abstract: We demonstrate photonic synthesis of broadband radio-frequency (RF) waveforms suitable for ultra-wide bandwidth (UWB) systems via open-loop reflection-mode dispersive Fourier transform optical pulse shaping. Using this technique, we synthesize broadband burst, monocycle and pulsed waveforms with RF bandwidths ranging from /spl sim/1-8 GHz. Through appropriate optical waveform design, we demonstrate direct control over the shape of the RF spectrum - a capability that enables us to tailor our RF waveforms to conform to the low-power UWB spectral criteria.

Compact dual-band microstrip bandpass filter without external feeds

Abstract: A compact dual-band microstrip bandpass filter is proposed and designed to operate at 2.4 and 5.2GHz without needing any external impedance-matching block. The modified half-wavelength stepped-impedance resonator with sinuous configuration is constructed to simultaneously excite the dual resonances at these two specified frequencies with miniaturized overall size. The parallel-coupled microstrip line is properly characterized to minimize the return losses within both dual passbands. The optimized results exhibit the good dual-band filtering performances with return losses higher than 20dB as well being confirmed by experimentation with a fabricated filter circuit.

A small wideband microstrip-fed monopole antenna

Abstract: A small microstrip-fed monopole antenna, which consists of a rectangular patch and a truncated ground plane, is presented for ultra wideband application. The proposed antenna is designed to operate over 3.1 to 11GHz for S/sub 11/<-10dB. Good return loss and radiation pattern characteristics are obtained in the frequency band of interest.

Realizing an electronically tunable reflectarray using varactor diode-tuned elements

Abstract: Electronically tunable reflectarrays hold significant promise as cost effective architectures for RF beamforming applications. The successful operation of these arrays depends on the phase agility of the cells used to realize the array. This letter describes the design of an electronically tunable reflectarray based on a novel cell architecture that provides a large degree of phase agility. Experimental results demonstrating the beamforming capabilities of the array at 5.8 GHz are presented.

Wideband microstrip-fed monopole antenna having frequency band-notch function

Abstract: A novel and compact ultra-wideband (UWB) microstrip-fed monopole antenna having frequency band notch function is presented. To increase the impedance bandwidth of an antenna, a narrow slit is used. By inserting a modified inverted U-slot on the proposed antenna, the frequency band notch characteristic is obtained. The designed antenna satisfies the voltage standing wave ratio requirement of less than 2.0 in the frequency band between 3 and 11 GHz while showing the band rejection performance in the frequency band of 5.0 to 5.9 GHz.

A broadband series power divider using zero-degree metamaterial phase-shifting lines

Abstract: A metamaterial 1:4 series power divider that provides equal power split to all four output ports over a large bandwidth is presented, which can be extended to an arbitrary number of output ports. The divider comprises four nonradiating metamaterial lines in series, incurring a zero insertion phase over a large bandwidth, while simultaneously maintaining a compact length of /spl lambda//sub 0//8. Compared to a series power divider employing conventional one-wavelength long meandered transmission lines to provide in-phase signals at the output ports, the metamaterial divider provides a 165% increase in the input return-loss bandwidth and a 155% and 154% increase in the through-power bandwidth to ports 3 and 4, respectively. In addition, the metamaterial divider is significantly more compact, occupying only 2.6% of the area that the transmission line divider occupies. The metamaterial and transmission line dividers exhibit comparable insertion losses.

Compact microstrip bandstop filter using open stub and spurline

Abstract: A compact wideband high-rejection microstrip bandstop filter (BSF) is presented This filter combines two traditional BSFs: open-stub filter and spurline filter Due to the inherently compact characteristics of the spurline, the proposed filter shows a better rejection performance than open-stub BSF without increasing the circuit size From 37 to 54 GHz, the proposed BSF has a rejection of better than 20 dB and the maximum rejection level of 61 dB Application of this BSF to suppress the second harmonic of an open-loop ring bandpass filter is also investigated with a 40-dB suppression improvement achieved

A planar triangular monopole antenna for UWB communication

Abstract: A planar triangular monopole antenna (PTMA) is presented for high-frequency structure simulator ultra-wideband (UWB) communication. The high-frequency structure simulator three-dimensional electromagnetic solver is employed for design simulation. A printed PTMA has been realized by using the FR-4 printed circuit board substrate. The measured voltage standing wave ratio is less than 3 from 4 to 10 GHz. In the UWB communication frequency range, the measured phase distribution of the input impedance is quite linear and the H-plane patterns are almost omni-directional. The Kirchhoff's surface integral representation was adopted in the developed finite-difference time-domain code to compute the far field distributions from the near filed ones in time-domain. This is to investigate the radiated power density spectrum (PDS) shaping to comply with FCC emission limit mask. The effect of various source pulses (first-order Rayleigh pulses with /spl sigma/ of 20, 30, and 50 ps) on the radiated PDS shaping is also studied.

Design of sharp-rejection and low-loss wide-band planar filters using signal-interference techniques

Abstract: A new class of sharp-rejection, low insertion-loss wide-band planar filters is presented in this letter. The proposed filter topology uses transversal signal-interference filtering sections made up of two transmission-line segments connected in parallel. Thus, under signal-interaction principles, the filtering action comes about through the generation of multiple out-of-band power transmission zeros and constructive in-passband signal combinations. Design equations and guidelines to adjust both the bandwidth and the out-of-band performance of the filtering response through the design parameters of the transversal section are also provided. Furthermore, the theoretical results are validated with the manufacture and characterization of an ultra-wideband microstrip filter prototype at 5 GHz.

Ultra wideband monopole/dielectric resonator antenna

Abstract: A hybrid antenna is presented, consisting of an annular dielectric resonator antenna combined with a quarter-wave monopole to simultaneously act as a radiator and a loading element, producing an ultra wideband response. A prototype antenna is designed and a 3:1 bandwidth is demonstrated.

Multilayered substrate integrated waveguide (MSIW) elliptic filter

Abstract: This letter presents the design and experiment of a novel elliptic filter based on the multilayered substrate integrated waveguide (MSIW) technique. A C-band elliptic filter with four folded MSIW cavities is simulated by using high frequency structure simulator software and fabricated with a two-layer printed circuit board process, the measured results show good performance and in agreement with the simulated results.

Compact and wideband microstrip bandstop filter

Abstract: A novel one-section bandstop filter (BSF), which possesses the characteristics of compact size, wide bandwidth, and low insertion loss is proposed and fabricated. This bandstop filter was constructed by using single quarter-wavelength resonator with one section of anti-coupled lines with short circuits at one end. The attenuation-pole characteristics of this type of bandstop filters are investigated through TEM transmission-line model. Design procedures are clearly presented. The 3-dB bandwidth of the first stopband and insertion loss of the first passband of this BSF is from 2.3 GHz to 9.5 GHz and below 0.3 dB, respectively. There is good agreement between the simulated and experimental results.

A novel compact-size branch-line coupler

Abstract: A novel compact-size branch-line coupler without any implementation of lumped-elements, bonding wires, and via holes is proposed. In this study, the size of the proposed coupler occupied only 45% of the conventional branch-line coupler at 2.4GHz. The performances of the circuit can be competed with the conventional coupler. The element sizes of this coupler can be realized easily by using simply standard printed-circuit-board etching processes. It is very useful for applications in the wireless communication systems.

A novel power plane with super-wideband elimination of ground bounce noise on high speed circuits

Abstract: A novel L-bridged electromagnetic bandgap (EBG) power/ground planes is proposed with super-wideband suppression of the ground bounce noise (GBN) from 600Mz to 4.6GHz. The L-shaped bridge design on the EBG power plane not only broadens the stopband bandwidth, but also can increase the mutual coupling between the adjacent EBG cells by significantly decreasing the gap between the cells. It is found the small gap design can prevent from the severe degradation of the signal quality for the high-speed signal referring to the perforated EBG power plane. The excellent GBN suppression performance with keeping reasonably good signal integrity for the proposed structure is validated both experimentally and numerically. Good agreement is seen.

A compact branch-line coupler using discontinuous microstrip lines

Abstract: We introduce a branch-line coupler using discontinuous microstrip lines whose size is significantly reduced relative to the standard design. We manipulate the reactive characteristics of discontinuities in its microstrip lines to achieve a physical size reduction of almost 60% with comparable performance.

A new wide-band planar balun on a single-layer PCB

Abstract: A new wide-band microstrip balun implemented on a single-layer printed circuit board (PCB) is presented in this letter. The proposed planar balun consists of a wide-band Wilkinson power divider and a noncoupled-line broad-band 180/spl deg/ phase shifter. To demonstrate the design methodology, one prototype is realized. The new design was simulated and validated by the measurement. Measured results show that 10-dB return loss of the unbalanced port has been achieved across the bandwidth from 1.7 GHz to 3.3 GHz, or 64%. Within the operation band, the measured return losses for both the two balanced ports are better than -10 dB, and the balanced ports isolation is below -1.5 dB. The measured amplitude and phase imbalance between the two balanced ports are within 0.3 dB and /spl plusmn/5/spl deg/, respectively, over the operating frequency band.

Harmonic suppression with photonic bandgap and defected ground structure for a microstrip patch antenna

Abstract: This letter presents a microstrip patch antenna integrated with two-dimensional photonic bandgap (PBG) and one-dimensional defected ground structure (DGS) jointly in ground plane. It is demonstrated that application of both PBG and DGS eliminates the second and third harmonics and improves the return loss level. Moreover, the combination use of PBG and DGS decreases the occupied area by 70% compared to the conventional PBG patch antenna.

A low-noise fixed-tuned 300-360-GHz sub-harmonic mixer using planar Schottky diodes

Abstract: This letter presents the design and fabrication of a low-noise fixed-tuned 300-360-GHz sub-harmonic mixer, featuring an anti-parallel pair of planar Schottky diodes fabricated by the University of Virginia and flip-chipped onto a suspended quartz-based microstrip circuit. The mixer exhibits a double side band (DSB) equivalent noise temperature lower than 900K over 18% of bandwidth (300-360-GHz), with 2 to 4.5mW of local oscillator (LO) power. At room temperature, a minimum DSB mixer noise temperature of 700K and conversion losses of 6.3dB are measured at 330GHz.

Substrate integrated waveguide (SIW) linear phase filter

Abstract: A planar four-pole linear phase filter centered at 10GHz based on substrate integrated waveguide (SIW) is proposed. The filter is composed of four side-by-side horizontally oriented SIW cavities, which are coupled in turn by evanescent waveguide sections with three direct coupling and one cross coupling between the first and fourth SIW cavities. The SIW cavities are fed by microstrips through coupling slots. A curve-fitting technique is adopted to improve the efficiency of the design process. The measured results are presented and compared with the results simulated by a high-frequency structure simulator. Good agreement between the simulated and measured results is observed.

High isolation and compact size microstrip hairpin diplexer

Abstract: Since conventional microstrip hairpin filter and diplexer are inherently formed by coupled-line resonators, spurious response and poor isolation performance are unavoidable. This letter presents a simple technique that is suitable for an inhomogeneous structure such as microstrip to cure such poor performances. The technique is based on the stepped impedance coupled-line resonator and is verified by the experimental results of the designed 0.9GHz/1.8GHz microstrip hairpin diplexer.

Linear tunable phase shifter using a left-handed transmission line

Abstract: We demonstrate a compact, linear, and low loss variation hybrid phase shifter using a left-handed (LH) transmission line. For frequencies from 4.3 to 5.6 GHz, this phase shifter gives a nearly linear phase variation with voltage, with a maximum deviation of /spl plusmn/7.5/spl deg/. Within this frequency range, the maximum insertion loss is 3.6 dB, and the minimum insertion loss is 1.8 dB over a continuously adjustable phase range of more than 125/spl deg/, while minimum return loss is only 10.2 dB. Furthermore, this phase shifter requires only one control line, and it consumes almost no power.

An iterative ADI-FDTD with reduced splitting error

Abstract: We present a new iterative alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method. By recognizing the ADI-FDTD method as a special case of a more general iterative approach to solve the Crank-Nicolson (CN) FDTD scheme, the splitting error in ADI-FDTD can be reduced systematically. Numerical examples are used to illustrate the improved accuracy of this method.

A compact 2.4/5.2-GHz CMOS dual-band low-noise amplifier

Abstract: This letter presents a fully integrated 2.4/5.2-GHz dual-band low-noise amplifier (LNA) for WLAN applications. By switching the input transconductance and the output capacitance, the narrow-band gain and impedance matching are achieved at the 2.4-GHz and the 5.2-GHz frequency bands. Using a standard 0.18-/spl mu/m CMOS process, a compact dual-band LNA with a chip size comparable to a single-band one is realized in the proposed topology for a minimum hardware cost. The fabricated circuit exhibits gains of 10.1dB and 10.9dB, and noise figures of 2.9dB and 3.7dB at the two frequency bands, respectively.

Dual-band, cross coupled branch line coupler

Abstract: A novel branch line coupler structure is proposed with application to the dual band operation. The proposed structure has additional cross coupling branches to the conventional branch hybrid coupler. Additional design freedom can be obtained using the proposed scheme, which can serve many useful purposes such as the dual band operation of the branch line coupler.

Enhancement of gain and radiation bandwidth for a planar 1-D EBG antenna

Abstract: This letter describes a technique to increase the radiation bandwidth and the gain of a classical planar electromagnetic band gap (EBG) antenna. Those two parameters are relative to the EBG material but also to the excitation, this second characteristic is studied here. The principle is to excite the EBG structure with several sources (instead of a single one classically). The performances depend on the number of sources and their spacing. Directivity and radiation bandwidth can be increased dramatically with few sources.

Miniaturized dual-mode bandpass filter using inductively loaded cross-slotted patch resonator

Abstract: An inductively loaded cross-slotted patch resonator is presented to build up a miniaturized dual-mode bandpass filter. By terminating the cross-slot on the square patch with the T-shape slot stubs, the resonant frequency is exhibited to be largely lowered due to an additional inductive loading, implying a capacity in size-miniaturization. In parallel, the rectangular slit is introduced at the four sides of the cross-slotted patch to facilitate the tightened parallel coupling between the feeders and resonator. A dual-mode filter with the patch size of /spl lambda//4 squared is then designed and predicted results are evidently supported by measurement.

Wideband simple cylindrical dielectric resonator antennas

Abstract: Bandwidths of the coaxial fed and aperture coupled cylindrical dielectric resonator antennas (DRAs) with broadside radiation patterns are enhanced by exciting the HEM/sub 11/spl Delta// (1