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A scheme of generating millimeter‐wave signals with 16 times frequency using a cascaded Mach–Zehnder modulator (MZM) is proposed. Optical delay lines (ODLs) are used to place between cascaded MZMs, two MZMs work at the maximum transmission point. By controlling the modulation index of the MZM and the delay of the ODL, 0‐order, ±8 $\pm 8$‐order, and ±12 $\pm 12$‐order sidebands can be generated. The optical phase shifter and attenuator are adjusted to eliminate the 0‐order sideband, and the photodetector output generates a frequency 16‐tupling millimeter wave (MMW). In the simulation platform, a 160‐GHz MMW signal can be obtained by taking a 10‐GHz radio frequency signal as the driving signal of two MZMs. The optical sideband suppression ratio is 29.92 dB, and the radio frequency sideband suppression ratio is 24.89 dB. Further, the effect of system performance on optical devices under nonideal conditions is also discussed. [ABSTRACT FROM AUTHOR]

In this work, a comb‐line leaky‐wave antenna with a pair of wide stubs is proposed with enhanced gain and reduced cross‐polarization. To ensure broadside scanning, three sections of transmission lines are used in the stub with the longitudinal offset. The stubs are placed half‐wavelength apart on both sides of the delay line to achieve high gain and a low‐cross polarization level. The antenna provides 46.8% impedance bandwidth with |S11| below −10 dB. The maximum measured gain and total efficiency are 18.5 dBi and 85%, respectively. The optimized broadside frequency of the leaky‐wave antenna is 10.2 GHz. [ABSTRACT FROM AUTHOR]

A novel resonant‐type group delay controller based on third‐order resonant topology with tunable central frequency and coupling coefficients is proposed. The coupling structure is realized by coupled line resonators loaded with two shunt capacitors for coupling coefficient tuning, and a series capacitor for resonant frequency tuning, then the group delay and working frequency can be tuned. The structure has the advantage of a large range of tunable coupling coefficients and breaks through the group delay tunable range of traditional delay circuits. The circuit is designed, simulated, and measured. The measurement shows that the group delay can be tuned from 5 to 20 ns with a tunable central frequency in the range of 0.8–1.05 GHz, and minimum ± 0.5 ns group delay bandwidth and −3 dB magnitude bandwidth of 12 MHz. [ABSTRACT FROM AUTHOR]

In this article, a single‐layer dual‐band reflectarray (RA) antenna is proposed. The RA antenna operates at two separated frequency bands with separate feeds. A low‐profile dual‐band unit cell I is designed with a 2 mm thickness without an air layer, which comprises only one dielectric substrate and two layers of metal patches. To achieve 360° phase shift ranges at two bands, unit cell II is presented based on the phase delay line theory. On the basis of proposed unit cells, a single‐layer circular RA (D = 150 mm) is designed, fabricated, and measured. The measured results show a measured peak gain of 20.7 dBi at 10.5 GHz and a 1 dB bandwidth of 17% (9.8–11.5 GHz). Besides, a measured peak gain of 23.6 dBi can be achieved at 15 GHz, and the 1 dB bandwidth is 13.3% (13.8–15.8 GHz) at Ku band. [ABSTRACT FROM AUTHOR]

In this work, we consider the impact of spectral narrowing of 43Gb/s NRZ‐DPSK signals on the system performance. NRZ‐DPSK signals passing through reconfigurable optical add/drop multiplexer (ROADM) devices are subject to spectral narrowing due to the narrow bandwidth of ROADMs. For a system level analysis of this phenomenon, we model the ROADM devices as a bandpass filter, the bandwidth of which is deliberately decreased. The dependence of the system performance on the delay time between adjacent bits in the receiver is also investigated. It is shown that the performance of signals passing through ROADM devices can be improved with an appropriate delay line interferometer (DLI) for any amount of devices. These results were obtained by simulating the whole system performance using different values of the BPF bandwidth and FSR. We present a technique for finding the optimal FSR of DLI that allows for improving the performance of NRZ‐DPSK systems in the presence of spectral narrowing of the channel. Improved bit error ratio is achieved by using optimized FSR for each BW. [ABSTRACT FROM AUTHOR]

An 86 to 94 GHz balanced resistive mixer (BRM) is presented using a 65 nm complementary metal‐oxide‐semiconductor (CMOS) process. We minimize parasitic losses which are serious at high frequency by adopting symmetric transistor structures. A low loss 180° hybrid is implemented using an asymmetric broadside coupler and delay lines. This allows low‐loss implementation of 86 to 94 GHz BRMs, which represent a conversion loss of 10.3 to 13.0 dB from 86 to 94 GHz of RF frequencies. The balanced designs produce LO‐to‐RF isolations of 32 to 36 dB from 87 to 93 GHz. The proposed CMOS BRM shows competitive results when compared to GaAs‐ or InP‐based balanced resistive mixers having moderate LO power requirements. [ABSTRACT FROM AUTHOR]

A compact dual‐band circularly polarized (CP) filtering patch antenna is proposed by adopting the dispersive delay line (DDL) in this article. The in‐band and out‐of‐band phase differences of two orthogonal components are effectively controlled by the DDL to realize opposite polarization states. As perfect isolation is achieved between left‐hand circular polarization and the right‐hand one in CP antenna, by controlling the parameters of DDL, four radiation nulls are presented simultaneously, and their locations are directly determined by the phase difference, thus obtains good filtering performance with compact structure. For demonstration, dual‐band CP patch antenna is designed at 2.4 and 5.8 GHz for WLAN applications based on DDL. The simulated and measured results of fabricated prototypes show good agreement. Good out‐of‐band rejection is observed in this design, which verifies the feasibility of the proposed CP filtering strategy. [ABSTRACT FROM AUTHOR]

In this article, a cross cancellation power amplifier (CCPA) with negative group delay circuits (NGDCs) for an efficiency enhancement is proposed. The proposed CCPA with NGDCs consists of a balanced power amplifier (BPA), NGDCs, error amplifier, small signal amplifier, and magnitude/phase control circuits. The NGDC can remove delay elements of the conventional CCPA and improve output power and efficiency. The fabricated main BPA provides 44.37 dBm peak power, 71.3% drain efficiency, and 68% PAE at 2.14 GHz. The drain efficiency of the proposed CCPA with NGDCs is improved by 6.7% than the conventional CCPA. Moreover, adjacent channel leakage ratios of CCPA with NGDCs are improved by 12.2, 18.9, 17.7, and 14.2 dB at −10, −5, +5, and +10 MHz offset points with the WCDMA 4‐FAs (20 MHz) signal, respectively. [ABSTRACT FROM AUTHOR]

Two linearly and circularly polarized filtering antennas with low profile, broad bandwidth, and improved gain are proposed. Without increasing the antenna profile, a vertically coupled resonant structure, which can broaden the bandwidth and provide the filtering response, is employed. To prove the concept, a broadband linearly polarized (LP) filtering antenna is designed by integrating the hairpin resonator on the feed, U‐slot resonator in the ground and the patch resonator. Then, we design a broadband circularly polarized (CP) filtering antenna, which utilizes a single‐feed dual‐coupled structure for two coupling routes with 90° phase difference to excite two orthogonal resonant modes without power divider and phase delay line. Both antennas exhibit third‐order filtering characteristics with improved bandwidths and flat in‐band gain. The equivalent circuits of both antennas are discussed. The LP and CP antennas achieve an impedance band of 28% and 29.6%, respectively. The CP antenna shows a 3‐dB axial ratio bandwidth of 17.6%. Both antennas also exhibit the high gain of 9.5 dBic with less than 0.6 dB variation within the band. [ABSTRACT FROM AUTHOR]

A delay line method for a distributed optical fiber vibration sensing system is reported. The sensing system is a combination of non‐balanced Sagnac/Mach‐Zehnder structure and an adjustable optical fiber delay line. The vibration location principle is the expansion of conventional null‐frequencies theory, which needs to adjust the length of delay line, in order to determine a zero point in the amplitude variation curve of detected light intensity for one characteristic frequency appearing in the vibration signal spectrum. Moreover, the location simulation using delay line method for narrowband vibration signals is affected. Finally, the experiment verifies that the location errors of vibration events are within ±70 m. The main advantage of proposed method is that it can locate not only the broadband vibration but also the narrowband vibration. [ABSTRACT FROM AUTHOR]

Abstract: This article proposes the design of a three‐layered balanced circularly polarized (CP) antenna using two tightly stacked conventional single‐ended CP slot antennas. With a 180° delay line inserted into one of the two feeding microstrip lines that form the balanced feedline, differential‐mode (DM) input signals can excite CP radiation in the broadside directions with a measured (simulated) axial ratio of as low as 1.3 (0.86) dB. Common‐mode (CM) input signals can be well rejected with a measured (simulated) CM return loss of <0.4 (0.5) dB in the DM impedance band. In addition, only a very small proportion of the CM (DM) input signal is converted into a DM (CM) reflected one. These nice properties of the possibly first reported balanced CP antenna were all achieved without placing before the radiation element a CM‐suppression filter. [ABSTRACT FROM AUTHOR]

Abstract: A curved photonic band gap (PBG) unit cell loaded bent differential line is proposed to suppress the differential‐to‐common mode conversion noise. The PBG unit cell, loaded at the bend is designed and optimized to provide the required delay characteristic on the inner transmission line of a differential line. An LC equivalent circuit of curved PBG unit cell is proposed and constituent lumped element parameters are calculated. The realized PBG loaded bent differential line exhibits a measured mode conversion noise below −20 dB from DC to 6 GHz demonstrating a common mode noise suppression of around 9 dB. [ABSTRACT FROM AUTHOR]

A novel circuit scheme is presented for the design of reconfigurable negative group delay circuit (RNGDC) with very low signal attenuation (SA), which is based on a lossy coupled-line Microstrip (MS) resonator. Theoretical analysis indicates that reconfigurable characteristics in the proposed circuits can be obtained by tuning the resistance of the variable resistor, which is loaded at a specific point on the MS resonator. Based on the study of one-stage RNGDC, a two-stage RNGDC arranged in an anti-symmetrical manner is designed to provide an extended reconfigurable negative group delay range. To validate the performance of the proposed circuit scheme, the prototypes of one-stage and two-stage RNGDC have been designed working at a center frequency of 1.73 GHz. Measured results of the two-stage RNGDC exhibit a group delays variation of −2 ns to −10 ns with signal attenuation variation of −4.5 dB to −9.3 dB at the center frequency, which demonstrates much lower SA compared to the previously-reported RNGDCs. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel model of injection-locked dual optoelectronic oscillator (ILD-OEO) is proposed and verified by experiments in this article. We not only built an accurate model for ILD-OEO but also analyzed the influence of fiber length on the white noise-limited phase noise of ILD-OEO. Results show that the single sideband (SSB) phase noise would increase when fiber delay line is long enough. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2568-2571, 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT A planar, lightweight, crossed dipole antenna with circularly polarized (CP) radiation is introduced for application in a radiofrequency identification handheld reader at ultrahigh frequency bands. The dipoles cross through a 90° phase-delay line of a vacant-quarter printed ring that enables broadband characteristic in terms of impedance matching and 3-dB axial ratio (AR) bandwidths. Four printed inductors are symmetrically inserted into the dipole arms whose ends are barbed to achieve a compact size. A sample antenna with a size of 60 × 60 × 0.508 mm and weight of 3.6 g is designed, fabricated, and measured. The proposed antenna yields an impedance bandwidth of 851-941 MHz for |S11| < −10 dB and a 3-dB AR bandwidth of 902-921 MHz. At 910 MHz, the antenna radiates bidirectional CP waves with a gain of 1.4 dBic and an AR of 1.1 dB. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1874-1878, 2013 [ABSTRACT FROM AUTHOR]

A fluid and its housing are integrated on a coplanar waveguide circuit surface, realizing a variable delay line. Performance tradeoffs for different fluidic housing shapes are investigated. Simulation and measurement results for two circuits are shown with the housing filled with air or de-ionized water. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:789-793, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27434 [ABSTRACT FROM AUTHOR]

A new technique for implementing an equivalent continuously tunable high-resolution microwave photonic bandpass filter is presented.It is based on applying frequency conversion to the RF signal before and after high-resolution bandpass filtering. Experimental results are presented, which demonstrate the continuously tuning of a high-resolution microwave photonic bandpass filter. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2584-2587, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27142 [ABSTRACT FROM AUTHOR]

This article presents the design of ultra-wideband (UWB) true-time-delay lines (TTDLs) operating in microwave frequency.The design is inspired by the use of composite right/left-handed transmission line (CRLH TL) unit cells as the true-time-delay elements to obtain large time delay. A rotated version of the CRLH TL unit cell is used to achieve UWB operation. A periodic microstrip line (PML) employing a sawtooth-shaped periodic pattern is used to further increase the time delay. For comparison, TTDLs using the conventional CRLH TL unit cells, the PML and the right-handed transmission line (RH TL) are also designed, optimized and fabricated. Simulation and measurement results show that, for a same length of 60 mm, our proposed TTDL has an ultrawide operating bandwidth and much larger time delay than those of the PML and RH TL ones. Moreover, it has the advantages of high return loss and low insertion loss. Finally, for easily fitting to practical circuits which normally occupy rather even widths and lengths on the printed circuit boards, the proposed straight UWB TTDL is bent to form different shapes such as circular, rectangular and meander. Results show that the performance of the TTDL is not degraded by bending into these shapes. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26228 [ABSTRACT FROM AUTHOR]

In this article, a frequency-tunable 150W harmonic-tuned power oscillator is presented. The harmonic-tuned power amplifier of the oscillator was designed for improving drain efficiency with a single laterally diffused metal oxide semiconductor transistor using a nonlinear harmonic balance simulation code. The oscillation frequency was tuned by a mechanical phase shifter in the delay-line feedback loop circuit. Experimental results show that the output power and the drain efficiency of the oscillator were almost same as in the power amplifier with the same transistor and operating in the same frequency range. The measured output power and drain efficiency of the fabricated oscillator were 51.8 ± 0.6 dBm and better than 55.9%, respectively, across the 902-928 MHz band. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1459-1462, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25970 [ABSTRACT FROM AUTHOR]

A highly efficient and linear inverted Doherty power amplifier (IDPA) with unsymmetrical delay path is presented. To compensate the phase difference between carrier and peaking cells, an additional offset line is inserted at the input path of the carrier cell. For verification, the IDPA with unsymmetrical delay path is implemented using two 50-W Si LDMOSFETs and tested using a continuous wave (CW) and a one-carrier wideband code division multiple access (WCDMA) signals at 2.6 GHz. From the measured results, the proposed IDPA shows not only an increase in the gain and the power-added efficiency, but also superior adjacent channel leakage ratios improvement. After the digital predistortion linearization, the proposed IDPA shows better improved linearity than conventional IDPA, and also meet the linearity requirement of the WCDMA signal without decreasing efficiency. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1302-1305, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25962 [ABSTRACT FROM AUTHOR]

A wideband correlator, with 45% relative bandwidth is proposed at the frequency range of 3.0–5.1 GHz. The structures of the correlator components such as the delay line and the Wilkinson power divider are designed to be realized in transmission line using the Agilent's Advanced Design System. The correlator made by using three unique wideband 3-dB couplers, rat-race coupler, and one 3-dB Wilkinson power divider to reach the required bandwidth. The insertion loss, amplitude imbalance, and phase imbalance between ports are presented. The proposed correlator makes compact size better than correlator of conventional structure. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1771–1774, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25305 [ABSTRACT FROM AUTHOR]

Time delay lines based on periodic microstrip lines (PMLs) and composite right/left-handed transmission lines (CRLH-TLs) are proposed. Compared with ordinary microstrip lines, PMLs are more suitable to realize tiny time delays because of their slow-wave characteristics. Meanwhile, CRLH-TLs are chosen to realize large time delays due to their large and easy designable phase constant. Finally, a 9-bit time delay module is designed and fabricated as an example. It is shown that the present time delay module possesses the advantages of compactness, low-loss, precise, and easy fabrication. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1679–1682, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24409 [ABSTRACT FROM AUTHOR]

In this article, propagation delay matched CMOS frequency doubler for L-band application is proposed. Schmitt trigger and voltage controlled delay line compensates duty cycle error and propagation delay mismatching that are induced as the frequency of operation is increased. As a consequence, unwanted harmonic components suppression is greatly improved for higher frequency of operation. CMOS frequency doubler is designed at the input fundamental frequency (f0) of 1.15 GHz and fabricated with TSMC 0.18 μm CMOS process. Measured output power at the doubled frequency (2f0) is 2.67 dBm for the input power of 0 dBm. The amount of harmonic suppression for f0, 3f0, and 4f0 are 43.65, 38.65, and 35.59 dB, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1729–1732, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24420 [ABSTRACT FROM AUTHOR]

This paper presents the design, simulation, fabrication, and characterization of a transmission delay line-based RFID tag. The ID generating circuit is designed based on the transmission delay line concept. A compact, inset-fed triangular patch antenna resonant at 915 MHz frequency is developed for integration with the tag application. The layout of the tag has been realized using conventional photolithography. Tags with a 5- and 10-ns delay ID generation circuits have been tested using input signals of 10-ns width. An OOK (On-Off Keying) modulation technique is employed for characterization of the tag. The received output consists of delayed signal from the tag added to the direct signal from the transmitter. Transmission delay line-based RFID technology can be exploited for low-end commercial applications that has a large market. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1900–1904, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22599 [ABSTRACT FROM AUTHOR]

Delay lines based on the left-handed transmission line (LH-TL) structure are designed and fabricated. Comparisons of the simulation and experimental results demonstrate validity of the present design. It can be found that the LH-TL time delay lines possess higher delay efficiency and more compactness than the traditional ones consisting of the right-handed transmission line (RH-TL). © 2006 Wiley Periodicals, Inc. Micorwave Opt Technol Lett 48: 1998–2001, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21836 [ABSTRACT FROM AUTHOR]

Because of the low crosstalk of the CrossPoint switch, multiple recirculations are possible. This facilitates simplified time-slot interchange configurations that depend on less fiber-delay lines, and single time-slot granularity to enable a short total-delay time. Error-free time-slot interchange is demonstrated with a 10-Gb/s payload. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 897–900, 2006; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21511 [ABSTRACT FROM AUTHOR]

Most adaptive linearization circuits for the nonlinear amplifier have a feedback loop that returns the output signal of the amplifier to the linearizer. The loop delay of the linearizer must be controlled precisely so that the convergence of the linearizer should be assured. In this Letter a delay control circuit is presented. It is a delay lock loop (DLL) with a modified early–late gate and can be easily applied to a DSP implementation. The proposed DLL circuit is applied to an adaptive linearizer with the use of a polynomial predistorter, and the simulation for a 16-QAM signal is performed. The simulation results show that the proposed DLL eliminates the delay between the reference input signal and the delayed feedback signal of the linearizing circuit perfectly, so that the predistorter polynomial coefficients converge into the optimum value and a high degree of linearization is achieved. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 117–121, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10391 [ABSTRACT FROM AUTHOR]

When the center frequency of a microwave pulse is tuned across the spectral range of a photonic bandgap (PBG) structure implemented in microstrip technology, the group delay introduced varies widely from high values to strikingly small values that give rise to superluminal propagation effects. In this paper, we explore this phenomenon, showing that the same behavior as for optical PBG devices is achieved. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 346–349, 1999. [ABSTRACT FROM AUTHOR]

We report on design, computer modeling, and experimental evaluation of delay lines fabricated with Nb, NbN, and YBCO superconducting thin films. Constrains resulting from the need to achieve long delays on small substrates and the unavailability of some directly applicable models for simulations will he addressed. [ABSTRACT FROM AUTHOR]

The use of optical fibers as the delay line element in radio frequency memory loops, promises light weight and small size devices with long time delays. This paper presents the experimental results and performance analysis of a 2-6 GHz fiber optic recirculating delay line. [ABSTRACT FROM AUTHOR]

Long delay lines can improve the performance and flexibility of radar test sets. Using a 2.25-km-long fiber optic link, we demonstrated generation of an ideal target for a radar repeater test set and measurement of phase noise closer than 100 Hz to a 9.6-GHz radar carrier signal using a delay line discriminator phase-noise test set. [ABSTRACT FROM AUTHOR]

ABSTRACT A switched delay line reconfigurable filter with high out-of-band suppression using double-behavior resonator (DBR) is presented. The novel filter has features of higher stopband rejection and easy processing compared to the conventional one. The DBR resonator can produce transmission zeros, which obviously improves the out-of-band suppression. The prototype of the filter operating at 1G/1.3G/1.6G with 50-dB suppression is designed and fabricated. The simulated and measured results show good agreement. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2438-2440, 2013 [ABSTRACT FROM AUTHOR]

An all-optical photonic bandpass filter which achieves a very high-Q performance while simultaneously exhibiting low noise operation, is presented. It can generate a large number of taps without the problem of lasing thus enabling the realisation of high-resolution bandpass filtering. Experimental results for a photonic filter demonstrate a Q factor of 407, together with low noise and a stopband rejection of 50 dB. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1284-1286, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26011 [ABSTRACT FROM AUTHOR]

This article presents a novel programmable high precision delay generator with adjustable digital control for ultra-wideband and time-domain RF applications.Ring oscillator based phase locked loop (PLL) is embedded to achieve desired propagation delay in the delay cell against process, temperature, and power supply variations. A replica inverter delay line parallel to the PLL offers a separate delay path for input clock. Sub-nanosecond delay step with high accuracy can be obtained by shaping the input clock slope and keeping a careful matching between the replica delay line and the delay cell in PLL. The prototype of the delay generator is implemented on a 0.18-μm CMOS process. The measurement results show relative delay error of 0.8%. The circuit consumes 9.5 mA from a 1.8-V power supply. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:390-392, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25732 [ABSTRACT FROM AUTHOR]

The article presents a Doherty power amplifier (DPA) with both high efficiency and good linearity for GSM base station using LDMOS transistors. Prepositive delay line structure (PDL) is proposed to satisfy the performances, both higher efficiency and better linearity are achieved. The test results show the proposed DPA reached an efficiency of 43.2% and an IMD3 of -47 dBc at 6 dB back-off power, which is about 19% and 6.5 dBc improvement, respectively than the class AB amplifier, and the improvement is about 4% and 12 dBc, respectively compared with the DPA without PDL structure. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 493–495, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24917 [ABSTRACT FROM AUTHOR]

In this paper, we study the benefits of using multiple fibers per link in optical packet-switched networks. The node architecture is presented and various contention resolution schemes are evaluated. Comparisons are made between the multifiber switch with a small number of wavelengths per fiber and the traditional single-fiber switch with a large number of wavelengths per fiber. The analytical and simulation results show that although the multifiber switch cannot easily perform as well as a switch with full wavelength conversion, compared to the traditional switch, it significantly reduces the number of wavelength converters and fiber delay lines while achieving a lower packet-loss rate. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 376–378, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20474 [ABSTRACT FROM AUTHOR]

We propose a novel optical packet synchronizer for use in telecommunication networks at a 1.5 μm wavelength. An experimental setup shows the feasibility of the system using an acousto-optic deflector and a single-mode fiber delay line array. The proposed system achieves an optical transparency to the data bit rate, and is suitable for nonregenerative application within an optical network. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 394–396, 2000. [ABSTRACT FROM AUTHOR]

The effect of row withdrawal in surface acoustic wave reflective dot array dispersive delay lines has been investigated, and the simulated multifrequency; constant fractional chirp bandwidth operation of such a device has been experimentally validated. Utilizing appropriate input / output interdigital transducers, the approach enables higher frequency and increased time-bandwidth product operation of reflective array devices, with relaxed mask-making and lithography constraints. [ABSTRACT FROM AUTHOR]

The first demonstration of a new S-shaped single-mode fiber loop resonator is presented. The S-shaped fiber loop resonator is made with a nonplanar 3 x 3 fiber directional coupler and two fiber delay lines. Expressions for the circulating (resonant) fields and the transmitted and reflected output fields are derived. Theoretical and experimental results show that this fiber loop resonator may have potential applications as a spectral filter and a closely spaced two-channel wavelength division multi-demultiplexer. [ABSTRACT FROM AUTHOR]

Theoretical results on a double serial amplified recirculating delay line are presented. Its application as filter is emphasized, showing a wide flexibility of design by appropriate choices of its main parameters: loop length, gain, and coupling ratio of the couplers. [ABSTRACT FROM AUTHOR]

A novel 90° hybrid at the V-band using surface micromachining technology is designed and measured. It employs a uniplanar structure which is composed of parallel coupled microstrip lines and delay lines. Compared with the conventional hybrids, cascaded parallel coupled lines with delay lines can make the coupling tighter as the number of coupled lines grows. The measured insertion loss is less than 2 dB and the phase imbalance is less than ±5° at 60 GHz. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 770–771, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21470 [ABSTRACT FROM AUTHOR]