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A New and Simple Approach on Multi-Resonator Circuit Based Chipless RFID Tags for IoT Applications
(IEEE, 2020) Dogan, Engin; Gorur, Ali Kursad; Karpuz, Ceyhun; Gorur, Adnan
In this paper, a novel multi-resonator circuit as a chipless RFID tag is proposed for internet of things (IoT) applications. For this purpose, a simple geometrical transition between a dual-mode square loop resonator (DMSLR) and an open loop resonator (OLR) is introduced by means of a small patch. Two frequency codes can be obtained from a DMSLR, since it has two resonance frequencies. On the other hand, while an OLR is utilized, only one frequency code can be obtained. Thus, totally 3 frequency codes can be achieved from one resonator in a very simple way and 3(N) codes can be achieved by using N resonators. For demonstration, two circuits including 4 resonators were fabricated and tested.
A Novel Compact Microstrip Diplexer with Closely Spaced Channels
(IEEE, 2020) Gorur, Ali Kursad; Turkeli, Alper; Dogan, Engin; Karpuz, Ceyhun; Gorur, Adnan
A novel microstrip diplexer with closely spaced channels is introduced by using stub loaded dual-mode square loop resonators (DMSLRs). The proposed resonator is constructed by locating open-circuited stubs with narrow slits to the midpoints of a conventional DMSLR to achieve size reduction. By changing the number of narrow slits, resonant frequencies of the proposed resonator can be controlled. In order to design a diplexer with low channel frequency ratio, two stub loaded DMSLRs having different number of narrow slits are coupled to input and output ports by thin film capacitors. The designed diplexer was also fabricated and measured with a channel frequency ratio of 1.10. The channels were measured at 1.78 GHz and 1.96 GHz with the fractional bandwidths (FBW) of 5.4% and 5.3%, respectively. The measured insertion losses of the channels are 1.99 dB and 1.78 dB. Isolation between the output ports was obtained as better than 28 dB.
A Novel Compact Quad-Band Microstrip Bandstop Filter Design Using Open-Circuited Stubs
(IEEE, 2013) Karpuz, Ceyhun; Gorur, Adnan; Gorur, Ali Kursad; Ozek, Ahmet
A novel compact quad-band microstrip bandstop filter design is presented. Input and output ports of the filter are connected with a high impedance transmission line. Proposed filter is designed by using open-circuited stubs attached to the input and output ports. Thus, based on the f(r) - 3f(r) harmonic property of the stub-loaded resonators, four stopbands at 1.15-2.22, 2.94-4.56, 4.95-6.98 and 8.26-8.96 GHz are obtained. Insertion losses of all stopbands are better than 15 dB inside the stopbands. Under the even and odd mode excitations, resonance conditions of the structure are also investigated. For the experimental verification of the simulated results, proposed filter has been fabricated. Simulated and measured results are in a good agreement.
A Novel Compact Wideband Bandstop Filter Design Using a Dual-Mode Square Loop Resonator
(IEEE, 2016) Sahin, Elif Gunturkun; Gorur, Ali Kursad; Karpuz, Ceyhun; Gorur, Adnan
In this paper, a novel compact wideband microstrip bandstop filter is presented by using a dual-mode square loop resonator having stepped impedance sections located at the lateral arms. The proposed resonator is directly connected to Input/Output (I/O) ports to obtain a wide stopband and loading elements are also employed to control the zeros and poles. The transmission-line model is used to explain the design methodology clearly. Simulated and measured responses show an excellent agreement.
A Novel Dual-Wideband Four-Port MIMO Filtenna for Sub-6 GHz 5G Communication Systems
(IEEE, 2023) Turkeli, Alper; Gorur, Ali Kursad; Altuncu, Yasemin
In this study, a new dual-wideband four-port multi-input multi-output (MIMO) filtenna structure is presented for sub-6 GHz 5G communication systems. Each filtenna element on the MIMO structure is constructed by coupling a dual-wideband filter to the feeding line of a conventional broadband monopole antenna. Four identical filtenna elements are arranged perpendicular to each other for the sake of high isolation and polarization diversity. Furthermore, a new isolation performance improvement approach is introduced by locating a patch decoupling element on the ground plane. The designed four-port MIMO filtenna was fabricated and measured in a very good agreement. The frequency bands were measured at the center frequencies of 3.3 and 5.75 GHz with the fractional bandwidths of 42.4 and 22.6 %, respectively.
An alternative application to tune the center frequency of a microstrip balun bandpass filter
(Institute of Electrical and Electronics Engineers Inc., 2019) Ozdemir, Pinar Ozturk; Ozturk, Ali; Gorur, Ali Kursad; Karpuz, Ceyhun; Gorur, Adnan
In this paper, a novel microstrip balun bandpass filter with tunable center frequency is presented. The proposed structure is constructed by open loop resonators having varactor diodes. The varactor diodes are used to tune the resonant frequency of the resonators. By virtue of coupled open loop resonators with varactor diodes, two bandpass filters in different filtering characteristics are designed at same center frequencies. Those filters can also operate in a range of 1.8-2.2 GHz depending on the changes in the capacitances of varactor diodes. The proposed balun bandpass filter is carried out using the presented filters. For demonstration, the proposed circuit was fabricated and tested. Experimental results exhibit an acceptable agreement with the estimated results. © 2019 EuMCE.
Asymmetric Response Dual-Mode Dual-Band Bandstop Filters Having Simple and Understandable Topology
(IEEE, 2009) Karpuz, Ceyhun; Gorur, Adnan; Gunturkun, Elif; Gorur, Ali Kursad
A novel simple and understandable topology is proposed for dual-mode dual-band bandstop filters with asymmetric frequency response. Two microstrip square loop resonators are used to obtain the dual-band filter characteristic. Each resonator uses a perturbation element to excite dual-modes. Distinct characteristics of new filters are investigated using full-wave electromagnetic simulations. It is also found that there are five reflection zeros. Three of them are inherently associated with the proposed topology, whereas the other reflection zeros near stopbands are associated with the perturbation. They may be easily adjusted by changing the size of the perturbation element. Four dual-band filters using dual-mode resonators are demonstrated with different asymmetric responses, which result from different locations of adjustable reflection zeros. Both simulated and measured results are presented and exhibit dual-mode dual-band bandstop responses with high sharpness.
Compact Wilkinson Power Dividers Based on Narrow Slits Loaded Transmission Lines
(IEEE Computer Society, 2023) Karpuz, Ceyhun; Gorur, Ali Kursad; Cakir, Mehmet; Cengiz, Alperen; Gorur, Adnan
In this paper, a new approach based on the utilization of narrow slits to improve the return loss and isolation levels of the Wilkinson power dividers is proposed. 2-, 4- and 8-way power dividers are designed by using narrow slits on the quarter wavelength transmission lines. The proposed circuits are designed at the center frequencies of 2, 2.1 and 2.05 GHz. The fractional bandwidths (FBWs) for the return loss of better than 15 dB and isolation levels of better than 20 dB are 19.7%, 28%, 28.2 % for 2-, 4-, and 8-way power dividers, respectively. The proposed method can also reduce the circuit size about 25 % and more in the 2-way and 4-way (8-way) circuits, respectively. Three circuits have been fabricated and measured in a very good agreement with the simulated results. © 2023 IEEE.
Design of a Compact Dual-Band Microstrip Bandstop Filter with High Rejection Levels
(Institute of Electrical and Electronics Engineers Inc., 2021) Sahin, Kursat Oguzhan; Gorur, Ali Kursad; Gorur, Adnan
In this paper, a novel compact dual-band microstrip bandstop filter with third order Chebyshev filtering function is presented. Meandered open-circuited stubs and meandered transmission lines are used to design the proposed filter within a compact circuit size. Both stopbands can be independently controlled with respect to the changes in the open-circuited stubs. The designed filter with the center frequencies of 1.13 and 3.47 GHz with the 3-dB fractional bandwidths of 46.4 % and 15.3 % was fabricated and measured to validate the proposed model. The measured results exhibit an excellent agreement with the simulated ones. Rejection levels at both stopbands have been measured as better than 29 dB. © 2021 Chamber of Turkish Electrical Engineers.
Design of a compact microstrip quadruplexer with closely spaced switchable and tunable channels based on asymmetrical dual-mode loop resonators
(Elsevier Gmbh, 2020) Gorur, Ali Kursad; Turkeli, Alper; Karpuz, Ceyhun; Gorur, Adnan
In this letter, a switchable microstrip quadruplexer based on asymmetrical dual-mode loop resonators (ADMLRs) is presented. Four ADMLRs at different electrical lengths for creating four channels are coupled to input/output (I/O) ports by means of thin film capacitors. Each resonator has two patch elements behaving as reference capacitors that are needed for switching process. In order to achieve the switching ability, varactor diodes are employed to provide variable capacitances at each resonator. Thus, all channels can be independently switched on/off by changing the capacitances of the varactor diodes. Moreover, all channels have fine bandwidth tuning mechanism depending on the capacitance changes. The designed quadruplexer was fabricated and the measurements were observed in a good agreement with the predicted results. Center frequencies of the proposed quadruplexer are adjusted to 1.8, 2.1, 2.4, and 2.7 GHz with the frequency ratios between the adjacent channels of 1.17, 1.14, and 1.13. Isolations between the outputs have been observed as better than 28 dB.
Design of a Novel Dual-Wideband Filtenna
(IEEE, 2022) Turkeli, Alper; Gorur, Ali Kursad; Altuncu, Yasemin
In this paper, a novel microstrip-fed filter-antenna (filtenna) exhibiting dual-wideband response is introduced. In this direction, a dual-wideband bandpass filter is designed first and then it is integrated into the feed line of a wideband monopole microstrip antenna. The dual-wideband bandpass filter is constructed by stub loaded multi-mode resonators. Two types of stub-loaded multi-mode resonators are coupled to the feeding lines from the filter's input and output ports. The proposed topology allows controlling both bandwidths independently. The designed filtenna was fabricated for the experimental verification. Measurements of the fabricated filtenna show a good agreement with the simulated results. Center frequencies of the proposed filtenna are 3.23 and 5.65 GHz with the fractional bandwidths (FBWs) of 46 % and 21.6 %.
Design of Dual-Mode Dual-Band Bandpass Filter with Independently Tunable Bandwidths and Reconfigurable Filtering Characteristics
(IEEE, 2017) Gorur, Ali Kursad; Karpuz, Ceyhun; Gorur, Adnan
In this paper, design of a tunable dual-mode dual-band microstrip bandpass filter is presented. The designed filter is constructed by using two nested dual-mode resonators (DMRs) having two patch capacitances located at the lateral arms of the resonators as reference elements. Varactor diodes are used instead of perturbation elements in order to excite the degenerate modes. Linear phase and quasi elliptical filtering characteristics can be independently obtained in each passband and the bandwidths can also be tuned at both filtering characteristics. For the experimental verification of the designed structure, a dual-mode dual-band microstrip bandpass filter was fabricated and measured. Center frequencies of the passbands were adjusted to 1.78 - 2.65 GHz and 1.83-2.7 GHz for linear phase and quasi elliptical filtering characteristics, respectively. Insertion losses in each passband were observed as better than 3 dB in measurements.
Design of dual-mode dual-band bandpass filter with independently tunable bandwidths and reconfigurable filtering characteristics
(Institute of Electrical and Electronics Engineers Inc., 2017) Gorur, Ali Kursad; Karpuz, Ceyhun; Gorur, Adnan
In this paper, design of a tunable dual-mode dualband microstrip bandpass filter is presented. The designed filter is constructed by using two nested dual-mode resonators (DMRs) having two patch capacitances located at the lateral arms of the resonators as reference elements. Varactor diodes are used instead of perturbation elements in order to excite the degenerate modes. Linear phase and quasi elliptical filtering characteristics can be independently obtained in each passband and the band-widths can also be tuned at both filtering characteristics. For the experimental verification of the designed structure, a dual-mode dual-band microstrip bandpass filter was fabricated and measured. Center frequencies of the passbands were adjusted to 1.78-2.65 GHz and 1.83-2.7 GHz for linear phase and quasi elliptical filtering characteristics, respectively. Insertion losses in each passband were observed as better than 3 dB in measurements. © 2017 IEEE.
Design of Microstrip Bandstop Filter with Adjustable Wide Passband Using Folded Open-Circuited Stub Resonators
(IEEE, 2009) Gorur, Adnan; Karpuz, Ceyhun; Gunturkun, Elif; Urhan, Mehmet; Gorur, Ali Kursad
This paper presents a new class of microstrip bandstop resonator filters. The folded open-circuited stub resonator located into microstrip loop structure is investigated using full-wave electromagnetic simulations. The utilization of the novel stub resonator allows a compact bandstop filter configuration to be realized. The proposed filter not only has a compact size, but also has a wider upper passband. Both simulated and measured results are presented to demonstrate the proposed filter.
Design of N-Way Wilkinson Power Dividers with New Input/Output Arrangements for Power-Halving Operations
(Mdpi, 2023) Karpuz, Ceyhun; Cakir, Mehmet; Gorur, Ali Kursad; Gorur, Adnan
In this paper, new single/double-layer N-way Wilkinson power dividers (WPDs) were designed by using slow-wave structures such as narrow-slit-loaded and meandered transmission lines. For size reduction, the slit-loaded and meandered lines were used instead of the quarter-wavelength transmission lines of a conventional WPD. Based on the proposed approaches, two-, four-, and eight-way power dividers were designed, simulated, and fabricated. The fabricated 2-, 4-, and 8-way circuits were measured at the center frequencies of 2.03, 1.77, and 1.73 GHz, which are in excellent agreement with the predicted ones. The meandered transmission lines were also used to design WPD types with novel input/output port arrangements. For this purpose, two three-way WPDs were located on both sides of the same board to have different power-splitting ratios at different inputs and outputs in order to provide alternative solutions for antenna arrays. Furthermore, a five-way dual-layer WPD was introduced by locating the meandered transmission lines into two layers. The most important advantage of the proposed 3- and 5-way WPDs is that they allowed the input power at the next output port to be halved, in the order of P/2, P/4, P/8, P/16, and P/16. All the designed power-halving WPDs were simulated, fabricated, and successfully tested.
Design of Quad-Band Bandpass Filter Using Nested Dual-Mode Square Loop Resonators
(IEEE, 2014) Karpuz, Ceyhun; Gorur, Ali Kursad; Ozek, Ahmet; Karaca, Zuhra
In this letter, design of a quad-band microstrip bandpass filter is presented by using nested placed four dual-mode square loop resonators (DMSLR) having different electrical lengths. Arms of the square loop resonators (SLR) are formed with low/high impedance parts, in order to obtain a maximum miniaturization by nesting DMSLRs and perturbation effects by changing the lengths of low impedance parts for the excitation of degenerate modes. Thus, the proposed configuration allows the control of mode frequencies, bandwidths and transmission zeros for each passband individually. Resonators are coupled to input/output (I/O) ports by feedlines having open-circuited stubs which suppress the harmonics. A dual-mode quad-band bandpass filter has been designed with an electrical length of 0.25 lambda(g) x 0.25 lambda(g) and fabricated, where lambda(g) is the guided wavelength at 1.79 GHz (the lowest resonance frequency). Measured and simulated results are in a good agreement.
Design of Tunable Microstrip Bandstop Filter
(IEEE, 2016) Gorur, Ali Kursad; Karpuz, Ceyhun; Gorur, Adnan; Dogan, Engin; Uysal, Baris
In this paper, a novel microstrip bandstop filter with tunable center frequency and bandwidth is introduced. A dual-mode square loop resonator and three varactor diodes are used to achieve the tunability operation. The dual-mode square loop resonator is coupled to a straight transmission line that connects input and output ports. One of the varactors is used as a perturbation element on the symmetrical axis of the resonator and even mode resonance frequency can be tuned by changing the capacitance of its. Remaining two varactors are located at the lateral arms of the resonator as reference elements and they have task on the tunability of the odd mode resonance frequency. Depending on the capacitance changes of the varactors, both of center frequency and bandwidth of the stopband can be tuned. The designed filter was also fabricated and measured for the experimental verification of the predicted results.
Design of tunable microstrip diplexer with reconfigurable filtering characteristics based on dual-mode square loop resonators
(Wiley, 2020) Gorur, Ali Kursad; Dogan, Engin; Karpuz, Ceyhun; Gorur, Adnan
A novel compact microstrip diplexer with tunable centre frequencies and reconfigurable filtering characteristics at both channels is presented. The designed diplexer is constructed by coupling two dual-mode square loop resonators (DMSLRs) having different electrical lengths. The DMSLRs are investigated by virtue of the coupled line analysis to evaluate the resonance frequencies, transmission zeros and out-band insertion loss level more conveniently. Centre frequencies of both channels can be independently tuned by the varactor diodes utilised instead of perturbation and reference capacitances. Depending on the specialised values of perturbation and reference capacitances, filtering characteristics of both channels can be reconfigured in terms of transmission zeros. The designed diplexer was fabricated and tested for the experimental studies and the measurements were obtained in a good agreement with the predicted results. Tuning ranges of the measured centre frequency in the first channel are between 1.23 and 1.43 and 1.35 and 1.64 GHz for the filtering characteristics with right- and left-side transmission zeros, respectively. In the second channel, they are 2.07-2.31 and 2.14-2.51 GHz for the filtering characteristics with real- and imaginary-axis transmission zeros, respectively. Isolation between two channels has been obtained better than 22 dB.
Design of UWB microstrip bandpass filter using stub-loaded quintuple-mode resonator
(WILEY, 2016) Sahin, Elif Gunturkun; Gorur, Ali Kursad; Karpuz, Ceyhun; Gorur, Adnan
Design of a novel ultra-wideband (UWB) microstrip bandpass filter is presented by using a square loop quintuple-mode resonator (QMR) having open-circuited stubs. The proposed resonator has five resonant modes in UWB band range and is coupled to Input/Output (IO) ports by parallel-coupled feed lines. The first three resonance modes are resulted from the stub loaded square loop resonator, whereas the remaining two modes can be formed by means of the coupling between the open-circuited stubs and the resonator. The designed UWB filter has totally seven poles including two poles resulting from the nature of the coupling sections and five poles from the QMR. Theoretical analysis of the resonator is realized by defining the equivalent circuit model. Coupling scheme and coupling matrix of the designed filter are also extracted to clarify the filter topology. In addition, two patch perturbation elements are used to control the in-band return loss levels. A seven pole UWB bandpass filter is designed, analyzed, and fabricated. Measurement results show a good agreement with the predicted results. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:662-666, 2016
Dual-mode dual-band microstrip bandstop filter design with independently tunable center frequencies
(Wiley, 2017) Gorur, Ali Kursad; Filiz, Ayse Nihan Basmaci; Dogan, Engin; Karpuz, Ceyhun; Gorur, Adnan
In this article, a novel dual-mode dual-band bandstop filter design with independently tunable center frequencies is presented by using dual-mode square loop resonators. Tuning operation can be achieved with a constant fractional bandwidth. Varactor diodes are used instead of perturbation and reference elements. Two dual-mode square loop resonators in different electrical lengths are coupled to a transmission line connecting input and output ports. Center frequencies of both stopbands can be independently tuned by changing the capacitances of varactor diodes of both perturbation and reference elements. While the perturbation and reference varactors tune even mode resonance frequency together, odd mode resonance frequency can only be tuned by reference varactors. The designed filter was also fabricated for the experimental studies and it exhibits acceptable tunability operations in measurements. Center frequencies of the first and second stopbands can be tuned between 2.2 and 2.54 GHz and between 3 and 3.38 GHz, respectively. Rejection levels for both stopbands were obtained as better than -13 dB in the whole tuning range.

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