To reduce the size and improve the performance, a 4th-order miniaturized dual-mode microstrip bandpass filter (BPF) is developed. A meander shorted stub loaded resonator is used, and much compact size is obtained. Theoretical model is set up, and the odd and even modes of the BPF are analyzed based on a symmetrical structure. Full wave simulation validates the design method. To verify the design, a fabricated BPF sample has been tested. Experiment result demonstrates that the designed BPF has wider stopband and better selectivity. Its fractional bandwidth and a center frequency are available.
A novel dual-band circularly-polarized slot antenna fed by a coplanar waveguide (CPW) is presented for digital multimedia broadcasting (2.6 GHz) and Worldwide Interoperability for Microwave Access (3.5 GHz) application. The circular polarization in the lower band is achieved by the slots loaded in two opposite corners, and corner truncation of the square slot can offer a current path for the upper band. Experimental results show that the measured impedance bandwidths (VSWR ≤ 2) are 18.5% for the lower band and 19.1% for the upper band, and the measured 3 dB axial-ratio bandwidths are 22.3% and 18.3%, with respect to 2.6 GHz and 3.5 GHz, respectively.
This paper presents the extension of the Maxwell Garnett effective medium model accounting for an arbitrary orientation of ellipsoidal inclusions. The proposed model is shown to be asymptotically convergent to the Maxwell Garnett mixing rule for a homogenous distribution of inclusions. Subsequently, a special case of a thin composite layer with a two-dimensional distribution of inclusions is considered and a simplified Maxwell Garnett formula is formally derived. The proposed model is validated against the alternative theoretical calculations and measurements data.
The backward wave oscillator is a promising and powerful source at THz frequencies. The rectangular corrugated waveguide is an effective solution as slow wave structure to design backward-wave oscillators (BWOs), suitable to be fabricated by photolithographic high-aspect ratio processes. However, assembling and vacuum pumping are a critical issue. In this paper, a corrugated waveguide with the width of the corrugation narrower than the waveguide width will be investigated as slow wave structure for BWOs. A relevant improvement from the point of view of the assembling, together with even better performance will be demonstrated. Two backward wave oscillators, at 1 THz central frequency, designed with conventional and narrow corrugated waveguide will be compared in terms of output power and frequency band of tuning.
We present an optical sampling technique that enables exploration of mismatches of a microstrip transmission line based on reflection analyses of electromagnetic pulses. The external electro-optic sampling scheme with a minute crystal detects high-speed electrical pulses over arbitrary locations of a line with very low-intrusiveness. The temporal pulsed signals measured with an on-wafer optical probing system and the corresponding spectra are obtained to analyze the transfer characteristics of a microstrip transmission line with 20 GHz bandwidth. The spectro-temporal response was cross-checked with commercial instruments. Applications of this optical probing technique to explore mismatches at the terminal port - based on both time and frequency domain reflectometry analyses - are also presented.
A four-layer metallization Cr-Cu-NiP-Au with amorphous and nonmagnetic NiP as a barrier layer is one of the promising candidates for use in microwave integrated circuits. Multi-section Wilkinson broadband 1:2 power divider circuits are delineated photolithographically on alumina substrates metallized by Cr, TiW, Ni, NiP, copper and gold using different metallization processes. The adhesion and dc resistivity are compared for different metallization scheme. Testing and evaluation have been carried out for multi-section Wilkinson broadband 1:2 power divider in the 10 MHz-6 GHz frequency range for Cr-Cu-Au, TiW-Ni-Au and Cr-Cu-NiP-Au to see the effect of NiP. Insertion loss, return loss and isolation are measured and compared. The microwave properties do not show any appreciable differences due to the various metallizations.
The novelty of this letter is that it capitalizes on noise waveform to construct measurement operator at the transmitter and presents a new method of how the analogue to digital converter (ADC) sampling rate in the monostatic multiple-input multiple-output (MIMO) noise radar can be reduced --- without reduction in waveform bandwidth --- through the use of compressive sensing (CS). The proposed method equivalently converts the measurement operator problems into radar waveform design problems. The architecture is particularly apropos for signals that are sparse in the target scene. In this letter, Estimates of both target directions and target amplitudes using CS for monostatic MIMO noise radar are presented. Sparse bases are constructed using array steering vectors. Orthogonal least squares (OLS) algorithm for reconstruction of both target directions and target amplitudes is implemented. Finally, the conclusions are all demonstrated by simulation experiments.
A low pass filter with ultra-wide band rejection and compact size using a proposed radial loaded transformed radial stubs is introduced and investigated. The implemented unite cell low pass filter with 1-dB cutoff frequency fc of 3.2 GHz demonstrates stopband rejection up to 11.8 fc i.e. 38 GHz. The design is further extended to the high-order LPF through cell cascading. The implemented four-cell LPF with fc of 3.6 GHz demonstrated 35dB rejection from 4.8GHz to 39GHz, 50 dB rejection from 5.4 GHz to 26 GHz (7.2 fc) and 20dB rejection from 4.4 GHz to 50 GHz (13.8 fc). The measured passband insertion loss is less than 1.7 dB, and group delay is from 0.45~0.8 nS. The size of the four-cell low pass filter is only 0.33λg × 0.135λg, (λg is the guide wavelength at center cutoff frequency) without using any lumped elements.
In this hybrid combined time domain (TD) and frequency domain (FD) approach, one can generate the early-time response using the method of marching-on-in-time (MOT) and use the method of moment (MOM) to generate the middle-frequency response, as the low frequency data may be unstable. The early-time and the middle-frequency data provide the missing low and high frequency response and the late-time response, respectively. Generation of a wide-band response using partial information of the TD data and FD data has been accomplished by the use of the continuous and discrete Laguerre functions.
A novel Ku-band push-push dielectric resonator oscillator (DRO) using substrate integrated waveguide (SIW) power combiner is presented. Compared with the traditional push-push oscillator, the proposed push-push DRO can realize high fundamental harmonic suppression, due to the use of a SIW power combiner, whose cut-off frequency is designed within the range of the fundamental and second harmonic frequency. Moreover, the isolation of two fundamental frequency oscillators can be enhanced, while the power combiner operates at the second harmonic frequency to maximize the output power. As shown in the experimental results, the centre frequency of push-push DRO is 14 GHz, with a frequency tuning range of 30 MHz. The suppression of the fundamental frequency is 28.59 dBc while the third harmonic suppression is 22.54 dBc, respectively. Furthermore, the phase noise can achieve -98.01 dBc/Hz at 100 kHz offset from the centre frequency.
This paper studies the bit error rate (BER) performance of non-coherent impulse-radio ultra wideband (IR-UWB) correlation receivers in the IEEE 802.15.3a channel for combined binary pulse amplitude modulation-pulse position modulation (BPAM-PPM) scheme. The BER performance is based on the channel averaged signal-to-noise ratio (SNR). The study includes simple transmitted reference (TR), differential TR (DTR), and energy detection (ED) receiver structures. Moreover, different performance parameters are addressed, namely the signal bandwidth integration window factor, number of pulses per bit, and receiver power consumption. ED receivers with BPAM-PPM are shown to outperform simple TR receivers and have a performance which approaches that of differential TR (DTR) receivers with smaller power consumption for the same design parameters.
P4 polyphase code is well known in microwave pulse compression technique. There are different reduction techniques to reduce the sidelobes of P4 code. This paper presents a new sidelobe reduction technique which its results are excellent. To valid our work, other sidelobe reduction techniques such as Woo filter and modified forms of Woo filter are investigated and compared with the technique presented in this paper. Results show that the method introduced in this paper produces better peak side lobe ratio (PSL) and integrated side lobe ratio (ISL) than other solutions.
This work introduces and investigates various methods of improving spurious-free dynamic rage (SFDR) in HBT transimpedance distributed amplifiers by trading off transimpedance gain. The methods are theoretically analyzed in detail with design examples, compared against each other in terms of performance and the best tradeoff is determined. SFDR improvements of up to 9 dB are reported in our design examples.
This paper deals with the challenges related to evaluating the performance of Multiple Input Multiple Output (MIMO) antenna based on Long Term Evolution (LTE) system within an underground mine environment at 2.4 GHz. Actual measured channels parameters have been used in simulation tools based on Agilent SystemVue software. The results suggest that LTE is able in practice to support multi stream transmission with very high data rates in an underground mine gallery.
An integrated Terahertz {Mach-Zehnder} interferometer is presented in order to perform differential measurements in a chip. Both simulation and experiment are performed for validating the interferometer structure. Destructive interference peaks are observed, and destructive frequencies are predicted by a mathematical model with a good agreement. The structure is then used to characterize dielectric constant of materials. Simulation results enable to quantify the device sensitivity. An experimental validation is given with the characterization of a thermosensitive polymer (Cyclotene BCB) in the sub-THz frequency band. Perspectives to increase investigated frequencies are discussed.
A uniplanar corner-fed patch antenna is presented with single-point microstrip feed and single layer substrate. Two orthogonal polarized dominant modes TM010 and TM001 are excited at two different frequencies. By utilizing a corner-fed structure, impedance matching for two bands can be adjusted much independently and the small ratio between two operating frequencies is easy to achieve. In addition, this simple and compact structure makes the patch antenna very convenient to form an array. A patch antenna operating at 12.5 GHz and 14.25 GHz with two linear orthogonal polarizations has been designed. The frequency ratio is only 1.14. The return loss, current distribution and radiation patterns of the patch element are investigated in detail. An 8 by 8 array has been developed, of which gains more than 23.4 dBi have been obtained at dual frequencies. Measured results agree well with simulated ones, which validate the proposed structure.
Considering the class of bi-isotropic media, a special case called the class of simple skewon (SS) media is defined. The SS medium depends on a single parameter. A plane wave incident on a planar interface of an SS medium is shown to reflect as from a DB boundary with vanishing normal components of D and B field vectors. This offers another possibility to realize the DB boundary conditions in terms of a medium interface. The same property is shown to apply for curved boundaries as well.
A printed ultra-wideband (UWB) monopole antenna with both tunable and switchable band-notched characteristics is proposed. An embedded resonant slot loaded with a varactor and a pin diode controlled by DC signal through one common bias network is employed to tune and switch the notch band. In the ``all-pass'' state when the two diodes are partially turned on, the power consumption of this active antenna is only 2.4 μW. Measured return loss, radiation pattern, gain and group delay of the introduced antenna are presented in this paper.
Microstrip bandpass filters using a triple-mode patch-loaded cross resonator are presented in this work. First, a square patch is added at the center of a cross resonator to separate the resonant frequencies of the 1st and 2nd modes. Then, a pair of narrow slots is etched into the square patch along its symmetrical plane to split the 1st resonant mode and its degenerate mode. By changing the patch size and the slot length, the above three modes are appropriately adjusted. Two prototype filters with open-ended and stub-loaded coupled-lines are designed and fabricated to verify the design principle and to further suppress the lowest harmonic passband, respectively. Predicted results agree well with the measured ones.
The characteristics of a two-dimensional (2D) left-handed traveling-wave field-effect transistor, which is two 2D composite rightand left-handed (CRLH) transmission lines with both passive and active couplings, are discussed for generating non-attenuated waves having left-handedness in 2D. In this study, the design criteria for wave amplification are described, and the results from numerical calculations obtained by solving the transmission equations for the device are presented.
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