Open Stubs Research Articles

Design and Simulation of Microstrip Hairpin Bandpass Filter with Open Stub and Defected Ground Structure (DGS) at X-Band Frequency

In this paper we have designed and simulated a Band Pass Filter (BPF) at X-band frequency. This filter is designed for X-band weather radar application with 9500 MHz center frequency and bandwidth -3 dB is 120 MHz. The filter design was performed using a hairpin microstrip combined with an open stub and defected ground structure (DGS). The substrate used is Rogers RT5880 with a dielectric constant of 2.2 and a thickness of 1.575 mm. Based on the simulation results, it is found that the filter works on frequency 9,44 - 9,56 GHz with insertion loss value at pass band is -1,57 dB.

High selectivity seventh‐order wideband bandpass filter using coupled lines and open/shorted stubs

A compact seventh-order wideband bandpass filter (BPF) with sharp roll-off skirts using coupled lines and open stubs (OSs)/shorted stubs (SSs) is proposed. Seven transmission poles in the passband and four deep transmission zeros from 0 to 2f 0 (f 0 denotes centre frequency of the passband) can be realised with the help of half-wavelength OSs and quarter-wavelength SSs. For demonstration, a wideband BPF prototype is designed, fabricated with a measured 3-dB fractional bandwidth of 78% (1.22–2.77 GHz) and transition band roll-off rates of over 175 dB/GHz. Good agreement between the simulations and measurements validates the design method.

Compact Band-Pass Filters Based on Parallel-Coupled Lines with Open Stubs

In this paper, two parallel coupled line band-pass filters are proposed. The proposed parallel coupled line band-pass filters are composed of the parallel coupled lines and open stubs. The equivalent circuit of the proposed parallel coupled line band-pass filter is proposed and analyzed. By using odd–even mode analytical method, the design equations are derived. The relation between the center resonant frequency of the proposed band-pass filters and the electrical length is analyzed. The relation between the fractional bandwidth and the impedances is discussed. Two proposed parallel coupled line band-pass filters are designed, fabricated and measured based on the calculated results. The spurious frequencies of the proposed filters are suppressed and the transmission zeros improve the filters’ selectivity. The measured results and the simulated results show good agreement with each other, which verifies the design theory.

Dual wide‐band miniaturized negative group delay circuit using open circuit stubs

AbstractIn this letter, dual band negative group delay circuit (DBNGDC) utilizing a couple of one quarter guided wave length ( ) open circuited stubs (OCSs) is presented. The centre frequencies ( ) are fully controlled with the stub lengths. On the other hand, the target negative group delay (NGD) is obtained using couple of resistors ( ) that connect each OCS to the main microstrip line. The designed DBNGDC accomplishes 52% size diminution compared with smallest size has ever been achieved before. Moreover, 0.2 and 0.4 GHz zero‐NGD bandwidths (BW) are achieved.

Reduced size of the λg/4 transmission line using immitance scaling for RF device applications

AbstractThis article presents the proposed reduced size of the λg/4 transmission line (TL) using immitance scaling. The proposed compact size of the TL is used for immitance scaling, which is composed of folded open stubs and series TL. It can be the design for distributed elements instead of lumped elements in a shunt capacitor, which is therefore called the folded open stubs. The proposed compact TL can be applied to a Wilkinson power divider (combiner), hybrid branch line coupler, and stub band‐pass filter in microwave applications.

A Novel Compact Wideband Power Divider with Ultra-wideband Harmonic Suppression

A compact wideband power divider based on the coupled lines and open stubs is presented in this paper. The proposed power divider has many advanced properties involving excellent input return loss, wide working band, high in-band isolation, ultra-wideband stopband, and outstanding harmonic suppression. The two sections of coupled lines are used to extend the passband while the open-circuit stubs are adopted to achieve ultra-wide stopband by introducing three transmission zeroes. Furthermore, high isolation within the operating band is realized with two resistors. The detailed design theories and procedures are provided in this paper. A power divider prototype with 10-dB bandwidth of 157.8% operating from 0.17 to 1.44 GHz and ultra-wide stopband from 2.04 to 5.07 GHz below − 30 dB is designed, fabricated, and measured for demonstration.

A Novel Wideband Filtering Power Divider With Embedding Three-Line Coupled Structures

This paper presents a novel wideband filtering power divider. Instead of the T-junction in the traditional power divider design, a three coupled-line structure is utilized to provide the equal power division to every outputs. Together with the quarter-wavelength coupled line in each way, a wideband filtering response can be obtained. In order to enhance the frequency selectivity, a pair of half-wavelength open stubs are loaded between the three-line coupled structure and parallel coupled lines to produce a pair of transmission zeros on both sides of the passband. To enhance the upper stopband rejection, two additional open stubs are installed at output ports. A new three-port equivalent network for the three-line coupled structure is proposed, and the circuit model for the filtering power divider can be developed for illustrating the working mechanism and the design process. Furthermore, the generalized Chebyshev function is applied to synthesize and analyze the whole structure systematically. For demonstration, a prototype of the wideband filtering power divider operating at 3 GHz is designed and fabricated. The measured results show a 16-dB bandwidth of 62%, an isolation better than 16.5 dB, and a 29-dB wide stopband from 4.39 to 7.73 GHz ( $1.1f_{0}$ ).

Bandwidth enhancement of a slot antenna with an open stub

AbstractA method to increase the bandwidth of a slot antenna is proposed. Slot antennas are not widely used in mobile terminals because they have narrower bandwidth than conventional inverted F antennas. To increase the bandwidth, in this letter, a stub with one end connected to ground is inserted into the slot. The stub resonance is combined with the existing slot resonance and widens the antenna bandwidth. It is important to impedance matching at resonant frequencies of both slot and stub when feeding the antenna. For this sake an inductor and a capacitor are connected in series with feed line. The bandwidth and efficiency of the proposed antenna are compared with those of the conventional antenna for the same slot size. The proposed antenna has an impedance bandwidth of 531 MHz, while the conventional antenna has a bandwidth of 165 MHz at 2.4 GHz for S11 < −10 dB. Moreover, the bandwidth more than 70% efficiency is 230 MHz (2.3 GHz–2.53 GHz) for the proposed antenna, while it is 510 MHz (2.3 GHz–2.81 GHz) for the proposed antenna.

Dual‐band bandpass filter using loop resonator with independently‐tunable passband

A dual-band microstrip bandpass filter using the rectangular loop resonator (RLR) is proposed. A microstrip open stub is implemented to perturb modes of the RLR, and the two modes form the low-frequency passband. The stepped impendence microstrip lines are adopted to excite the RLR and the lines also work as the resonant stubs, i.e. one is 3/4-wavelength resonance stub and another is full-wavelength resonance stub. As a result, the second passband is introduced. Furthermore, each passband can be tuned independently through the corresponding resonant paths (parameters), which are discussed in detail. Without the connection stub between stepped impendence microstrip lines and RLR, this dual-band bandpass filter will degenerate to a dual-mode single-band bandpass filter and the corresponding results are also obtained and demonstrated. The measured results agree with the simulated results well.

A Dual Band Frequency Reconfigurable Origami Magic Cube Antenna for Wireless Sensor Network Applications.

In this paper, a novel dual band frequency reconfigurable antenna using an origami magic cube is proposed for wireless sensor network (WSN) applications. The proposed origami antenna consists of a meandered monopole folded onto three sides of the magic cube. A microstrip open-ended stub is loaded on the meandered monopole. The proposed origami magic cube can be mechanically folded and unfolded. The proposed antenna operates at 1.57 GHZ and 2.4 GHz in the folded state. In the unfolded state, the proposed antenna operates at 900 MHz and 2.3 GHz. The resonant frequency of the second band can be tunable by varying the length and position of the open stub. The origami magic cube is built on paper. Its performance is numerically and experimentally demonstrated from S-parameters and radiation patterns. The measured 10 dB impedance bandwidth of the proposed origami antenna is 18% (900–1120 MHz) and 15% (2.1–2.45 GHz) for the unfolded state and 20% (1.3–1.6 GHz) and 14% (2.3–2.5 GHz) for the folded state. The measured peak gain at 900 MHz and 2.3 GHz are 1.1 dBi and 2.32 dBi, respectively, in the unfolded state. The measured peak gain at 1.5 GHz and 2.4 GHz are 3.28 dBi and 1.98 dBi, respectively, in the folded state.

Monitoring uniform and localised corrosion by a radiofrequency sensing method

A new method for atmospheric corrosion monitoring based on the variation of radiofrequency (RF) wave propagation in a resonator during its corrosion is presented. The ability of the proposed sensor to differentiate between uniform and localized corrosion mechanisms is demonstrated by considering two identical open stub microstrip resonators produced in zinc and aluminum materials, respectively. For that purpose, experimental characterization of electromagnetic wave propagation in the resonators and simulations are compared. The proposed sensitive resonator should therefore be considered as the key element of new corrosion mimetic sensors.

Low-Noise Amplifier Protection Switch Using p-i-n Diodes With Tunable Open Stubs for Solid-State Pulsed Radar

In this letter, a tunable protection switch device using open stubs for $X$ -band low-noise amplifiers (LNAs) is proposed. The protection switch is implemented using p-i-n diodes. As the parasitic inductance in the p-i-n diodes may degrade the protection performance, tunable open stubs are attached to these diodes to obtain a grounding effect. The performance is optimized for the desired frequency band by adjusting the lengths of the microstrip line open stubs. The designed LNA protection switch is fabricated and measured, and sufficient isolation is obtained for a 200 MHz operating band. The proposed protection switch is suitable for solid-state power amplifier radars in which the LNAs need to be protected from relatively long pulses.

High selective compact dual‐band filter using ring resonator with quarter‐wavelength stubs

A ring resonator loaded with five open stubs is proposed for the design of dual-band bandpass filters. To shrink the filter layout, a pair of loaded quarter-wavelength stubs is utilised to produce the first passband. On the other hand, the introduced coupling between the quarter-wavelength stubs and the ring resonator produced transmission zeros for enhancing the selectivity. Both bandwidth and central frequency ratio of the two passbands can be adjusted freely by the circuit parameters. Two coupling lines are added beside the resonator as feed-lines to construct a filter with high selectivity and compact size. A filter at 1.57/2.45 GHz is designed, fabricated and measured for verification.

Efficient feeding geometries for rectenna design at 2.45 GHz

Efficient feeding geometries for rectenna design at 2.45 GHz are described. The proposed rectenna consists of two layers low cost FR-4 substrates in which circular polarisation and harmonic rejection properties are embedded. A voltage doubler rectifier with open stub matching network and the radial stub is designed at the bottom substrate to transform the ac signals to a dc voltage. A right triangular slot is designed in the ground plane to suppress second and third harmonics which improves the rectenna conversion efficiency to 75.043% at an input power of 20 dBm. The proposed rectenna design has the advantages of providing circular polarisation and harmonic rejection with a compact size and low cost which makes it a good candidate for microwave power transmission applications.

Narrow-band Band-pass Filter With Harmonics Suppression

This paper presents a narrow-band band-pass filter with high selectivity and low insertion loss. The filter has a good characteristics of narrow-band filtering and harmonic suppression. Its harmonic suppression ability is realized by Transmission zeros which result from loading open stub coupling line. The center frequency and bandwidth is determined by the length of coupling line. Based on even-odd mode analysis and transmission line theory, the filter is analyzed and the formula is deduced. The central frequency of the filter is 6.63GHz, and its 3dB bandwidth is 290MHz. The minimum insertion loss in the pass-band is 0.44dB. The proposed filter has a suppression of -31dB in the two harmonic frequency points. In order to verify the theory and confirm the simulation results, the filter is fabricated and tested. And the measured results are in good agreement with the simulation results.

Balanced Tri-Band Bandpass Filter Design Using Octo-Section Stepped-Impedance Ring Resonator With Open Stubs

A balanced tri-band bandpass filter (BPF) is proposed based on octo-section stepped-impedance ring resonator (SIRR). The relation and design graphs between the differential-mode (DM) and common-mode (CM) characteristics with different physical parameters are analyzed. It reveals that the proposed SIRR has more degrees of freedom in controlling DM and CM characteristics for tri-band design with excellent out-of-band performances and high CM suppression. Moreover, the SIRR is loaded by open stubs with different lengths to further improve the CM suppression. Finally, a balanced tri-band BPF prototype is fabricated and measured. Good agreement between simulated and experimental results verifies this design method.

A Wideband Bandpass Filter With Reconfigurable Bandwidth Based on Cross-Shaped Resonator

A wideband bandpass filter (BPF) with reconfigurable bandwidth (BW) is proposed based on a parallel-coupled line structure and a cross-shaped resonator with open stubs. The p-i-n diodes are used as the tuning elements, which can implement three reconfigurable BW states. The prototype of the designed filter reports an absolute BW tuning range of 1.22 GHz, while the fractional BW is varied from 34.8% to 56.5% when centered at 5.7 GHz. The simulation and measured results are in good agreement. Comparing with previous works, the proposed reconfigurable BPF features wider BW tuning range with maximum number of tuning states.

A Novel Tri-Band Wilkinson Power Divider for Multiband Wireless Applications

This letter presents a novel and simple technique for the design of an arbitrary tri-band Wilkinson power divider. The proposed technique is based on the use of quarter-wave open stubs (QWOS) at the desired operation frequencies, placed at appropriate positions along the divider’s 50- $\Omega $ output transmission lines, to create the targeted tri-band response. These stubs present a high impedance at the frequencies of interest, while introducing transmission zeroes between the operation bands. For a compact design, slow-wave structure has been adopted to miniaturize the conventional divider’s arms. To validate the above concept, a power divider—intended to operate in the 1.5-, 1.9-, and 2.35-GHz frequency bands—is designed. The results of the fabricated circuit present low insertion loss of less than 0.45 dB while offering an isolation better than 15 dB in the three bands of operation. Compared to recently published results, the proposed divider exhibits the largest fractional bandwidth at each operation frequency. Furthermore, it can be easily extended to more bands by adding QWOS depending on the required number of bands.

RFIC 상에서 RF 필터 소형화에의 응용을 위한 마이크로스트립/코프레너 복합구조를 가지는 박막필름 Open stub의 RF 특성에 관한 연구

RFIC 상에서 RF 필터 소형화에의 응용을 위한 마이크로스트립/코프레너 복합구조를 가지는 박막필름 Open stub의 RF 특성에 관한 연구

A compact arbitrary power division coupler with nonstandard phase-difference

This paper presents a new coupler configuration which can be designed with both arbitrary power division and nonstandard phase difference at the output ports. The planar coupler ring is composed of four section microstrip lines and an open stub resulting in ease of fabrication. Its circuit parameters can be easily determined by the derived closed-form equations and the corresponding performance in terms of power division ratio, output phase difference, and the tunable parameters is mainly analyzed. Compared with the previous counterparts, its bandwidth and area have obvious superiority. For experimental verification, two prototypes, operating at 1 GHz, have been designed and implemented in microstrip process. One demonstrates a 45° phase difference with equal outputs and the other is designed for a 105° phase difference with 6.02 dB power division ratio. The design theory has been supported with good agreement between the simulated and measured responses.