Microstrip Lowpass Filter Research Articles

Compact microstrip lowpass filter with wide stopband and sharp transition band using radial stub resonator

This study introduces a compact microstrip lowpass filter that offers a wide stopband and a low transition band. The couple radial stubs are designed for having sharp roll-off. The filter has a −3 dB cut off frequency of 1.6 GHz, with a transition band ranging from 1.6 to 1.7 GHz with attenuation levels of −3 dB and −20 dB, respectively. To ensure a wide stopband, the filter utilizes bended transmission lines with stepped impedance suppressing cells, resulting in a stopband attenuation of 20 dB from 1.7 to 28 GHz. The insertion loss in the passband is less than 0.1 dB, and the overall size of the filter is 0.127 × 0.087 λg2.

Design of a Microwave Quadrature Hybrid Coupler with Harmonic Suppression Using Artificial Neural Networks

In this paper, a compact and simple structure of an elliptic microstrip lowpass filter (LPF) is designed for harmonic suppression in microwave quadrature hybrid coupler (QHC) applications. A radial resonator and a rectangular resonator are used to produce an elliptic LPF. The proposed LPF is used on the outer sides of the branch line coupler, which has improved the coupler harmonic suppression. Furthermore, artificial neural networks (ANNs) are incorporated to improve the LPF design process. The LPF best structure is obtained using the proposed ANN model. The proposed LPF has a compact size, which only occupies 16.4 mm × 7.3 mm equals to 0.164 λg × 0.073 λg, has a cut frequency of 2.2 GHz, and shows a sharp transmission band with a roll-off rate of 158.3 dB/GHz. Finally, the deigned QHC operates correctly at 1 GHz, which shows high harmonic suppression ability. The proposed QHC provides wide suppression band from 2.25 GHz up to more than 14 GHz, which can effectively suppress 3rd, to 14th harmonics. The proposed coupler features desirable parameters of S11, S21, S31, and S41, with magnitude of −21 dB, −3.4 dB, −3.3 dB, and −22.5 dB, at the operating frequency. The proposed approach mitigates the complexity of the circuit fabrication, compared with the previous methods while achieved desirable performances for the proposed QHC.

Analysis of microstrip low pass filter at terahertz frequency range in finite difference time domain method for radar applications

Analysis of microstrip low pass filter at terahertz frequency range in finite difference time domain method for radar applications

Compact lowpass filter with vast out-of-band rejection utilizing DGS

A unique low-profile microstrip lowpass filter (LPF) is introduced. It features a broad range of stopband and sharp roll-off. The suggested LPF is built utilizig a T-shaped configuration which includes a stub for resonance and utilizes open stubs as attenuator cells. To further improve the stopband, a double circular ring is engraved into the ground plane. The developed filter features a cut-off frequency of 3 dB at 3.4 GHz, a roll-off rate of 108 dB/GHz, and a stopband range from 3.7 to 22.8 GHz. The attenuation is less than −20 dB. The prospective LPF is designed using a lumped LC circuit model and validated using Keysight Advanced Design System (ADS) simulation and theory. The final design is realized using RT/Duroid 4003C, which boasts a small footprint of 12.4mm×8.69mm×0.8mm. The modelling findings and measurements of the suggested LPF are in fairly good agreement.

An intelligent digital twinning approach for complex circuits

The digital twinning process is essential for transferring real-world objects to the Metaverse by creating accurate digital versions, known as digital twins. However, complex systems pose challenges in this process. With the increasing utilization of microwave components and circuits in telecommunication systems such as IoT, 5 G, and 6 G, the need for digital twins of these components arises. Nevertheless, high-frequency components exhibit intricate behavior, requiring advanced modeling techniques. Artificial intelligence (AI) provides a powerful tool for enhancing the reliability and accuracy of estimated models in such cases. In this study, a microstrip lowpass filter (LPF) is designed, fabricated, and measured as the physical twin. An intelligent digital twinning approach is employed using a machine learning method based on an adaptive neuro-fuzzy inference system (ANFIS), trained by a subtractive clustering algorithm. The resulting digital twin of the LPF proves valuable for communication networks and IoT applications. Moreover, this research showcases the applicability and accessibility of machine learning in creating digital twins of electromagnetic components for communication cyber-physical systems (CPSs) and the Metaverse. Furthermore, the proposed method exhibits adaptability to various passive and active electrical or electronic circuits. By harnessing the potential of AI and digital twinning, this study presents a robust and accurate approach for modeling and analyzing complex circuits, specifically in the context of communication systems and their integration into the Metaverse. The findings highlight the advantages of an intelligent digital twinning approach and its potential for advancing various domains involving complex circuitry.

Passive Electrical and Optical Methods of Ultra-Short Pulse Expansion for Event Timer-Based TDC in PPM Receiver

The energy efficiency of a communication system using pulse position modulation (PPM) can be increased by reducing the duration of the pulses transmitted over the communication channel to several tens of picoseconds. The employment of an event timer device as a time-to-digital converter (TDC) for demodulation allows the use of PPM with many pulse positions and achieves competitive data transfer speeds. However, along with several-picosecond accuracy of modern event timers, they require a pulse duration of several hundred picoseconds for precise detection. This research is devoted to developing passive techniques for precise pulse expansion from tens of picoseconds to hundreds of picoseconds. We propose two methods: the electrical method, which employs a microstrip low-pass filter (LPF), and the optical method, which uses fiber Bragg grating (FBG). This research offers a detailed analysis of distortion-free pulse expansion requirements, the design of prototypes meeting these requirements, and experimental design verification. Theoretical background, mathematical models, and results of experimental validation of the proposed pulse expansion methods within the laboratory transmitted reference pulse-position modulation (TR-PPM) communication system are provided.

A Self-Assembled 3D-Shaped Microstrip Microwave Device Inspired by the Origami Structure

An innovative design method inspired by origami is proposed for the 3D-shaped microstrip microwave device in this paper. A self-assembled microstrip low-pass filter inspired by the origami structure is designed, fabricated, and measured. The experimental results of the prepared prototype demonstrate the validity of the origami-based design method for stereoscopic microstrip microwave devices. This work provides a simple method to fabricate thin stereoscopic metal structures of microstrip microwave devices.

Low Complexity Compact Lowpass Filter Using T-Shaped Resonator Loaded With a Stub

A novel miniaturized microstrip low pass filter (LPF) with a wide stopband and sharp roll-off is presented. The designed filter is developed by realizing a T-shaped structure loaded with a stub as a resonator and open-stubs as suppressor cells to achieve a simple structure for ease of fabrication process. The new filter with a symmetrical structure has a 3 dB cut-off frequency of 2.15 GHz, the transition band is 123 dB/GHz from -3 dB to -40 dB, a stopband with an attenuation level better than -20 dB from 2.4 up to 22.1 GHz with a compact size of 0.0132λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>g</i></sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The insertion loss in the passband is less than 0.3 dB and return loss is lower than -20 dB. The filter is fabricated, and the results show agreement between the simulation and measurement.

Design of Modified Jacobi Microstrip Lowpass Filter for L-Band Application

In this brief, a design of microstrip lowpass filter with the 1 GHz cutoff frequency is revisited, where a class of modified Jacobi polynomials is used for the filter design. The optimization procedure for these filters includes the passband return loss minimization and the roll-off factor enhancement using the magnitude correction of the transmission coefficient. Mentioned correction is performed by introducing the multiple transmission zeros such that LC ladder prototype filter can be realized symmetrically. Three seventh degree filters for L-band applications are realized and simulated: allpole, with a single and double transmission zeros. It is shown that, among these three stepped impedance lowpass filters realizations, the filter with simple transmission zeros offers the best performance.

Compact low-pass filter (LPF) with wide harmonic suppression using interdigital capacitor

Abstract In this article, a compact microstrip low-pass filter (LPF) with low in-band insertion loss and a wide attenuation band is recommended. The structure is modeled using two rectangular-shaped open resonators (ORs) loaded with multiple sections of the interdigital capacitor. The proposed LPF has a cut-off frequency of 1.5 GHz, a passband insertion loss of 0.35 dB, and an electrical circuit size of 0.02 λ g 2. In the ground plane, two dissimilar defected ground structures (DGSs) are introduced to generate additional attenuation poles for enriching the stopband performance of the LPF. The harmonics suppression is achieved up to 15 GHz with tenth harmonic suppression and relative stopband rejection of almost 165%. The EM simulated results show a well-matched behavior with the experimental ones. The proposed LPF can be used for global positioning systems (1500 MHz), telecommunications (1600 MHz), and audio broadcasting (1400 MHz) applications.

Design and implementation of a bioinspired leaf shaped hybrid rectenna as a green energy manufacturing concept

In this communication, the novel low cost hybrid energy harvester combining rectifying antenna with the solar cell for feeding the low power energy systems are reported. The bioinspired leaf shaped monopole antenna is designed to work in the most used communication frequency bands such as GSM-1800, UMTS-2100, WIFI-2.45 and LTE-2.65 GHz for the energy harvesting purposes and microstrip low pass filter is also added on the feeding line for the second harmonic rejection for increasing the efficiency of the harvester. The solar cell is placed on the ground plane of the designed leaf shaped antenna for using volumetric space efficiently and obtain a more compact system. The implemented prototype harvester generate 76 mV, 120 mV and 90 mV when the same type receiver antenna feed from the 25 dBm power from the RF source located at a distance of 1 m which satisfies the far field condition of the antenna without solar cell at the 2.15 GHz, 2.45 GHz and 2.65 GHz frequency bands, respectively. After the illumination of its solar cell component with 165 lux, the total harvested voltages are measured as 150 mV, 170 mV and 190 mV at the same frequency bands, respectively.

Design and Fabrication of Compact Microstrip Low-pass Filter with Thin Film Technique for Wideband Applications

This paper introduces a compact microstrip low-pass filter (LPF) with a very sharp rejection. The proposed LPF is designed to be used for electronic warfare in defense industry. It has 62 dB/GHz attenuation rate, 10 GHz of stopband width and 48.6 dB of stopband attenuation. Moreover, it also has a wide passband and has a high cut-off frequency (f_c) of 6 GHz. The designed filter has been fabricated using alumina (Al2O3) substrate and titanium-gold (Ti-Au) coating on top of that with thin film technique in a clean room. The experimental measurements of the proposed LPF show great agreement with the simulation results, which validates that the presented filter is convenient to be used for applications up to C-band in electronic warfare systems.

A lowpass filter implementation with an ultra sharp transition band and extended stopband bandwidth based on even-mode and odd-mode analysis of lumped circuits

In this paper, a microstrip lowpass filter employing a T-shaped resonator and high-impedance curved bend transmission lines loaded by rectangular patches operating at 2.4 GHz is presented. To improve the transition band slope, the above-mentioned cells have been coupled. Next, four attenuators composed of L-shaped and radial patches are placed symmetrically at both sides of the coupled resonators to broaden the stopband with an acceptable suppression level. By exploiting the even-mode and odd-mode analysis of the equivalent lumped circuit of each resonator and their combination, the relations of the transmission coefficient, reflection coefficient and the transmission zeros of them have been derived, independently. Studying these equations can clarify the roll of each lumped element and consequently its corresponding microstrip structure in the scattering parameters of the utilized cells. Employing the main resonators and the introduced suppressors results in a very steep roll-off rate (860.46 dB/GHz) and an acceptable relative stopband bandwidth (1.73) with the suppression factor of 2.53. From DC to 2.389 GHz, the insertion loss and return loss are better than 0.178 dB and 16.95 dB, respectively. Furthermore, the occupation area of this lowpass filter is 10.8 mm × 14.65 mm. Eventually, the designed filter has a high figure of merit equal to 110308.34.

Design of Microstrip Filter by Modeling with Reduced Data

Many design optimization problems have high-scale problems that require the use of a fast, efficient, accurate, and reliable model. Recently, artificial-intelligence-based models have been used in the field of microwave engineering to model complex microwave stages. Here, an eight-layer symmetrical microstrip low-pass filter (LPF) is modeled using a multi-layer perceptron (MLP) with reduced data with Latin hypercube sampling. It is used to obtain target−-test relationships in the MLP model along the frequency band whose electrical length in each layer determines the performance of the microstrip filter. Electrical length lower and upper limits were preferred in the widest range. The study presents the design and analysis of a non-uniform symmetrical microstrip LPF with a cutoff frequency of 2.4 GHz. Next, different network models are compared to find the variation of the non-uniform microstrip LPF around 2.4 GHz along the specified frequency band S1111 and S2222 (dB) for different electrical lengths. It has been observed that the network models of the microstrip LPF are both more computationally efficient and as accurate and reliable as the electromagnetic simulator.

A compact simple microstrip lowpass filter based on elliptical analyzed resonator

Abstract In this article, a compact microstrip lowpass filter (LPF) using elliptical shaped resonators with ultra-wide stopband is rendered. In this respect, LC equal structures of the elliptical shaped resonators are calculated based on the formula of circumference. In addition, to calculate transmission zeros of the presented elliptical shaped resonator, the LC equal structure and its output to input ratio are employed. The proposed LPF has a −3 dB cut-off frequency at 1.50 GHz and the stopband bandwidth of the designed filter is about 13fc, which refers to its ultra-wide stopband. The occupied circuit size of the presented filter is 0.151λ g × 0.044λ g (λ g is the guided wavelength at 1.50 GHz). The designed filter is fabricated on RT/Duroid 5880 substrate. The results of the fabricated and designed filter have clearly demonstrated that not only has the proposed LPF shown a suitable agreement between measured and simulated S-parameters, but also an appropriate stopband bandwidth.

A Microstrip Low-Pass Filter Design Using a Modified Radial Resonator in the Application of Aircraft Distance Measurement Equipment

In this paper, the application of microstrip technology is investigated in low-pass filters. A cascade microstrip low-pass filter with a sharp frequency response and a good cut-off bandwidth is presented using a modified radial resonator. The advantages of this proposed filter include minor losses in the transit band as well as the desired return. This filter design shows consistency when compared with the results of simulation and model performance. A comparison between the parameter values of this filter and previous structures indicates that it is desirable. The proposed filter can be used in modern communication systems such as aircraft distance measurement equipment (DME) antenna.

Investigations on Three-Pole Microstrip Low-Pass Filters Incorporated with DGS and Fractals for Selectivity Improvement

In this paper, an investigation on compact microstrip low-pass filters (MLPFs) with extremely perfect low-pass characteristics and improved out-band suppression has been carried out for the improvement of the selectivity parameter ([Formula: see text]). For this purpose, two different defected ground structures (DGSs) based on Moore fractals and Meander line have been designed and experimentally validated. The proposed third-order low-pass filter (LPF) configurations are designed and simulated using the High-Frequency Structure Simulator (HFSS). To validate the simulation models, the prototypes of the suggested low-pass filters are fabricated using Teflon (TM) substrate having a relative permittivity of 2.65 and a loss tangent of 0.001, and measured using the Vector Network Analyzer. The simulation and measurement results are in good agreement. The proposed filters occupy a compact size of [Formula: see text]. The selectivity parameter values for the proposed Moore fractals- and Meander line-modeled DGS-based LPFs are 425[Formula: see text]dB/GHz and 850[Formula: see text]dB/GHz, respectively. The proposed microstrip low-pass filters offer a significant improvement in the selectivity parameter, offering a maximum value of 850[Formula: see text]dB/GHz. The proposed filters exhibit a very high figure of merit (FOM), reporting 71,335 for Moore fractals-based LPF and 118,354 for the Meander line-based LPF. These proposed filters are suitable for advanced mobile phone services, [Formula: see text]-band radar, Global Positioning System, mobile, paging services, Wi-Fi, Bluetooth and wireless LAN.

Design of Microstrip Low-pass and Band-pass Filters using Artificial Neural Networks

Usually the design of microstrip filters is done using simulators and classical approximation methods as Butterworth and Chebyshev, these techniques takes a lot of time to run for designing filters. In this paper we develop a faster artificial neural network model for designing a microstrip low-pass and band-pass filters for all rang of operating frequency , when the input are the dimensions of filter, operating frequency, the features of substrate, and the output are the transmission and reflection coefficients. The database uses for training this model is generated by a linear simulator based on circuits model. Two filters designed by the developed model are a stepped impedance low-pass filter with a cut-off frequency of 1 GHz and a parallel coupled-line band-pass filter with fractional bandwidth of 25 % and a central frequency of 2.45 GHz. The results of simulation are compared with desired results and the effectiveness of this method has been proven.

Design and analysis simple microstrip low-pass filter for wireless application

In this article, high-performance compact defective ground technique based microstrip low-pass filter with and without dumble -shaped structure is proposed. By etching of dumble geometry on to ground plane, the presented filter gives a wideband operating frequency and sharp cut at stop band with high attenuation. The presented geometry is designed on software. The simulated outcomes shows that the presented low pass filter has very significant advantages in term of wide band stop band from 2.5 GHz to 6.6 GHz with the S21 much better than −35 dB and the presented LPF can meet the requirements of wireless communication systems and microwave applications with its stated efficiency.

Ku/Ka band diplexer based on thin-film technology for small ground-segment user terminals

AbstractThis paper describes the outcome of the “Small user TErminal multi band DIplexer” project where the goal is the validation of novel SMD-compliant planar diplexer. The real application scenario concerns an integrated multi-band radio terminal for ground-segment satellite links. The advantageous and novel approach involves the simultaneous use of three different well-established concepts: a microstrip low-pass filter, a substrate integrated waveguide high-pass filter, and the thin-film technology as manufacturing process. The proposed topology applied to a planar alumina-based design guarantees a 15 × 11.1 mm2 footprint and the best integration with surface mountable soldering process over standard PCB technology. Achieved performance and resilience to environmental toughness are suitable for consumer-oriented satellite links or man-pack applications. The designed component targets the Ku 10.7–12.75 (RX) and Ka 27.5–30 (TX) GHz bands but the layout can be easily tuned across the spectrum. The described solution has been manufactured and validated. Thermal cycling and mechanical tests have been carried out to prove the high technology readiness level of the proposed device.