Compact size and low insertion loss Chebyshev-function bandpassfilters using dual-mode patch resonators

A compact Chebyshev-function bandpass filter using dual-mode patch resonators is proposed. The filter presents 75% size reduction compared with the conventional Chebyshev bandpass filter using two square patch resonators. Because of inset feeding and only one coupling gap being required, the new filters can achieve a low insertion loss of 1.1 dB and reduce the fabrication uncertainties     

UMTS diplexer design using dual-mode stripline ring resonators

A novel design for a UMTS diplexer using dual-mode rectangular stripline-ring resonators is proposed. The diplexer comprises two parallel-oriented rectangular stripline-rings and a connecting line between them. The degenerate-mode resonance is used to form the diplexer's Tx and Rx-bands, and a method to improve the isolation is also proposed in this circuit design.     

Compact microstrip lowpass filter with very sharp roll-off using meandered line resonators

In this paper, a new compact size microstrip lowpass filter (LPF) with a very sharp roll-off is presented to apply in the modern wireless networks. The proposed LPF is designed using the series main resonators with meandered lines based on inductor-capacitor (LC) equivalent circuit analysis. The main goal is to achieve maximum-sharp roll-off by maintaining a wide stopband bandwidth and high return loss (RL). The main resonator of the proposed filter is consisted of two meandered line hairpin resonators (MLHR), and a meandered line T-shaped resonator (MLTR). The designed suppressor is composed of two coupled radial stubs to create a wide stopband. Low return loss in the passband, which has been created by the main resonator, is resolved by the suppressor structure with high return loss. The measured results show a ??3 dB cut-off frequency of 1.93 GHz. The very sharp transition band starts at 1.93 to 1.97 GHz (from ??3 to ??20 dB). The stopband is from 1.97 to 19.9 GHz (with the suppression level of ??20 dB). Also, the total size of the proposed LPF is only 13.3?×?10.1 mm².

     

Compact microstrip low-pass filter with sharp rejection

This letter presents a compact multisection sharp-rejection microstrip low-pass filter. Each section consists of a microstrip line section and an interdigital capacitor. The analysis for optimizing the attenuation poles by adjusting the finger number, and the width and length of the microstrip line section, is presented. The cascaded four-section low-pass filter has a return loss of better than 17 dB and an insertion loss of less than 0.7 dB from DC to 1.6 GHz. The rejection is better than 20 dB from 2.1 to 7.5 GHz.     

Compact lowpass filters with very sharp transition bands based on open complementary split ring resonators

It is shown that open complementary split ring resonators (OCSRRs) are useful particles for the design of lowpass filters with very narrow transition bands in microstrip technology. Owing to the small electrical size of OCSRRs, the filters are also very small. These filters are implemented by cascading several OCSRR stages in a microstrip line. The OCSRR stages can be modelled as parallel resonators in series configuration, thus providing a transmission zero at their resonance frequency. By designing the OCSRRs with small inductance and high capacitance, very sharp cutoffs are achieved. To illustrate the possibilities of the approach, a prototype device example is provided. It consists on a five-stage periodic microstrip lowpass filter with 3 dB insertion losses at 1.33 GHz and 40 dB rejection at 1.45 GHz. To improve out-of-band rejection, four additional OCSRR stages tuned at the spurious frequency band have been cascaded. Filter dimensions are 39 x 7.4 mm (i.e. 0.46l x 0.087l, where l is the guided wavelength at the cutoff frequency). These filters are of interest in applications where small size and severe cutoff requirements are required.     

High-selectivity single-ended and balanced bandpass filters using ring resonators and coupled lines loaded with multiple stubs

High-selectivity single-ended and balanced bandpass filters (BPFs) using dual-mode ring resonators and coupled lines loaded with multiple stubs are proposed in this paper. With the help of the loaded short-circuited and open-circuited stubs, six deep transmission zeros (TZs) from 0 to 2f₀ (f₀: center frequency of the passband) can be realized in both of single-ended and balanced BPFs to improve the stopband suppressions. The functions of the loaded short/open stubs and calculated analysis of TZs’ positions have been presented. For further demonstration, two examples of single-ended BPF and balanced BPF with high common-mode suppression are designed and fabricated, whose center frequencies are both at 2.1 GHz. Their measured 3-dB fractional bandwidths are 23.7% and 24.7% (differential-mode), respectively. The simulated results and measurements of these two filters are in good agreement.     

Compact microstrip low pass filter with flat group-delay using triangle-shaped resonators

In this paper, a compact microstrip lowpass filter (LPF) using triangle-shaped resonators is presented. The designed LPF includes three symmetric triangle-shaped resonators to provide a suitable passband and sharp response. A suppressing unit composed of several suppressing cells is designed to obtain a wide rejection band and low insertion loss in the passband. The fabricated LPF has been measured and indicts that it has −3 dB cut off frequency at 5.15 GHz. The rejection band has been expended from 5.51 GHz to 43.2 GHz with maximally flat return loss in this region nearby to 0 dB. Also, simulation and experimental results show that the proposed filter has a very flat group delay in the passband, which is the minimum value in comparison with the published works since 2017.     

Dual-mode quasi-elliptic-function bandpass filters using ringresonators with enhanced-coupling tuning stubs

A novel microwave dual-mode quasi-elliptic-function bandpass filter structure has been designed and fabricated. The filter uses L-shaped coupling arms for enhanced coupling and dual-mode excitation. The effects of varying the length of tuning stubs and gap size between tuning stubs and ring resonator have been studied. Filters using multiple cascaded ring resonators with high rejection band are presented. The new filters have been verified by simulation and measurement with good agreement     

Compact eight-channel wavelength demultiplexer using modified photonic crystal ring resonators for CWDM applications

An eight-channel wavelength demultiplexer by cascading of ring resonators (RRs) in photonic crystal (PhC) structure is proposed in this paper. In designing of this demultiplexer, we used eight square-shaped PhC RRs with different refractive index (RI) of defect rods to generate a distinctive resonance wavelength. Each PhC RR has a specific resonance wavelength with tuning a variety of design parameters such as RI of a whole, defect and inner rods and radius of defect rods. In operating wavelength of λ₀?=?1497 nm, the transmission power and quality factor (Q) of single RR are discovered as 96% and 1000, respectively. The average power transmission, channel spacing, crosstalk and full width at half maximum are found by finite difference time domain method to be about 96?±?1%, 2.25 nm, ??35 dB and 1.5 nm, respectively. Simulation outcomes demonstrate that the designed demultiplexer has a proper operation. The footprint of the designed device is about?~?115 μm², which makes this device a promising for future photonic integrated circuits.

     

Optical-fibre tap with low insertion loss

We report a fibre-tapping element which uses part of the insertion loss of a fibre connector or splice as useful optical signal power. A tapping fraction of up to 70% has been measured with a total insertion loss of 0.22 dB.     

Compact frequency and bandwidth tunable stopband filters using split ring resonators and varactors coupled transmission line

Two highly compact tunable stopband filters using microstrip transmission lines coupled with split ring resonators (SRRs) and varactor diodes are presented. Frequency or bandwidth tuning capability of each device is demonstrated. The frequency tunable filter, realized by a single stage, shows a wide tuning range of 19.8% with a maximum bandwidth of 5% and an insertion loss of approximately 20 dB at 4 GHz. The bandwidth tunable filter, realized by double stages, shows a 10-dB bandwidth of 19–34% with a biasing voltage of 0–10 V. The implemented frequency tuning and bandwidth tuning devices show a significant area reduction of 60.1% and 53.5%, respectively, in comparison with a similar frequency or bandwidth tunable structure presented by others. Equivalent circuit models are presented. The measured S-parameters are in good agreement with simulated ones.     

Compact microstrip-line-fed ring monopole antenna with tuning strip for 5 GHz WLAN operation

A novel compact and simple microstrip monopole antenna for 5 GHz wireless local area network (WLAN) operation is proposed. To excite a resonant mode in the operating band, a tuning strip is added to the antenna, which consists of a rectangular ring microstrip and a top loaded vertical strip, and is fed by a 50 /spl Omega/ microstrip line. The effects of the added strip to the impedance matching have been studied. A constructed prototype of the proposed antenna has been tested and bandwidth of about 930 MHz ranging from 5.03 to 5.96 GHz, monopole-like radiation pattern, and average gain of greater than 2.6 dBi over the operating band have been obtained.     

High-Q channel-dropping filters using ring resonators with integrated SOAs

The filter response of single-ring resonators with integrated semiconductor optical amplifiers based on GaInAsP-InP is presented. The devices with free spectral ranges of 25 and 50 GHz have the form of a racetrack. An on-off ratio of 20 dB, a full-width at half-maximum of 12 and 24 pm, a finesse of 17, and a Q factor of 130,000 and 65,000, respectively, have been achieved. The tuning to a specific wavelength is performed by using integrated Pt-resistors.     

低插入损耗多通道介质膜型光波分复用器

介绍了一种采用新型多级均衡方案的介质膜型光波分复用器。该波分复用器具有低插入损耗和插入损耗均匀性好的特性。在与阵列波导光栅(AWG)型器件的竞争中具有更多的优势,从而使介质膜型器件可以成为目前光通信系统中制作密集波分复用(DWDM)器件的主流技术。     

Compact dual-mode elliptic-function bandpass filter using a singlering resonator with one coupling gap

A novel microwave dual-mode elliptic-function bandpass filter with one coupling gap structure is proposed. This filter has a 4.7% bandwidth at 1.805 GHz with 1.73 dB insertion loss. The filter provides less field perturbation of the ring resonator than conventional filters. Without the output coupling gap between the feed line and the ring resonator, a low insertion loss has been obtained. This compact, high performance filter is useful for mobile and personal communication systems     

Very low insertion loss arrayed-waveguide grating with verticallytapered waveguides

We propose and demonstrate a very low insertion loss silica-based arrayed-waveguide grating (AWG) achieved using a novel structure, which has vertically tapered waveguides between arrayed-waveguides to reduce the slab-to-arrayed-waveguide transition loss. A spot-size converter is also incorporated in the AWG to reduce the fiber-to-waveguide coupling loss. The structure can be formed by a process involving the conventional photolithography and reactive ion etching. The structure provided a loss reduction of 1.5 dB. Moreover, we have successfully obtained a minimum insertion loss of 0.75 dB with a crosstalk of -40 dB and polarization-independent operation     

Asymmetric Fabry-Perot device arrays with low insertion loss andhigh uniformity

The authors report on arrays of normally on asymmetric Fabry-Perot modulator (AFPM) devices which exhibit a high degree of uniformity between devices, with a thickness variation across an array of 0.07%. The devices in one array have a mean insertion loss of 1.8 dB and have off reflectivities of less than 3%, giving a mean contrast ratio of 22:1. These characteristics are measured at a single operating wavelength of 857 nm. The spatial light modulators show promise for the use of AFPM devices in optical processing     

Compact microstrip lowpass filter with wide stopband and sharp roll-off using tapered resonator

In this article, a novel microstrip lowpass filter (LPF) with specifications such as sharp cut-off, wide stopband, low insertion loss and high return loss using tapered resonator is presented. The LPF has cut-off frequency of 1.11 GHz, where unwanted harmonics are suppressed by novel tapered cells. The bandwidth is enhanced, and the size is reduced as compared to the conventional tapered filter. The transition band is approximately 0.29 GHz from 1.11 to 1.4 GHz with corresponding attenuation levels of –3 and –20 dB, respectively. The stopband with greater than –20 dB rejection is from 1.4 to 8.9 GHz, insertion loss in the passband is less than 0.1 dB, return loss is less than –18 dB and the overall size of the filter is 0.12 × 0.073 λ_g. The proposed filter is fabricated and measured. The simulation and measurement results are in good agreement. This LPF is designed for microwave communication applications, especially wireless video transmitters.     

Ultra wideband bandpass filter with dual-notched bands using stub-loaded rectangular ring multi-mode resonator

This paper presents a new ultra wideband (UWB) bandpass filter (BPF) with dual-notched bands (at 5.2/5.7 GHz) using the stub-loaded rectangular ring multi-mode resonator (MMR). The proposed resonator consists of the dual embedded open-circuited stubs for introducing the dual notch bands and connected with a stub-loaded rectangular ring structure for controlling the two transmission zeros (at 3/11 GHz) at both sides of the UWB passband edge. This study mainly provides a simple method to design a UWB bandpass filter with high passband selectivity and dual-notched bands for satisfying the Federal Communications Commission (FCC-defined) indoor UWB specification. Experimental verification is provided and good agreement has been found between simulation and measurement.