Orcun Kiris

Bio: Orcun Kiris is an academic researcher from Scientific and Technological Research Council of Turkey. The author has contributed to research in topics: Power dividers and directional couplers & Antenna (radio). The author has an hindex of 4, co-authored 9 publications receiving 19 citations. Previous affiliations of Orcun Kiris include Middle East Technical University.

A Reflectarray Antenna Using Hexagonal Lattice With Enhanced Beam Steering Capability

Abstract: This paper presents a novel reflectarray antenna with enhanced beam steering capability. The reflectarray antenna is based on the hexagonal distribution of the unit cells on the antenna surface. The hexagonal topology changes the angle between the principal axes of the unit cell distribution, preventing the formation of the grating lobe, and improving the beam steering capability of the reflectarray antenna. To verify the proposed idea, two different sets of reflectarray antennas, which includes square and hexagonal lattice topologies with inter-element spacings of 0.52λ and 0.6λ, have been designed, fabricated, and measured at 8.23 GHz. The measurements of the all fabricated reflectarray antennas are in very good agreement with the simulations, and the comparison of the square and hexagonal topologies show that the beam steering capability can be improved by 50% for 0.6λ inter-element spacing by using a hexagonal topology. This improvement shows that a simple modification in the array configuration can be a viable solution for satellite and 5G communication applications that require increased beam steering capability.

Parametric analysis of double-split ring resonator as a reflectarray unit cell

Abstract: This work presents a parametric analysis of double split ring resonator (DSRR) for linear polarized X-band reflectarray antennas. We performed the parametric analysis on the unit cell of the reflectarray antenna, where we investigate the effects of the outer radius, ring width, ring gap, periodicity, and polarization on the resonance frequency and phase of reflected signal. Using the results of the parametric analysis, we designed two unit cells that operate at 8 and 12.5 GHz, respectively. The simulation results show that the designed unit cells provide 360° phase difference range by using element rotation technique. To the best of our knowledge, this is the first study that investigates the performance of DSRR structures as linearly polarized reflectarray elements.

Implementation of three-way power divider based on substrate integrated waveguide

Abstract: This paper presents the design, fabrication, and measurement results of an X-band 1×3 substrate integrated waveguide (SIW) power divider. The 1×3 SIW power divider provides equal amplitude with uniform phase distribution at each output port. These features are demonstrated by measurements experimentally. The amounts of measured power at the output ports are quite close to ideal power equality factor (4.77 dB) for three-way power division. Operating bandwidth of the fabricated divider is nearly 17.5% and reflection coefficient is better than −18.75 dB at the design frequency of 10 GHz as shown in both simulation and measurement results.

Three-way substrate integrated waveguide (SIW) power divider design

Abstract: In this paper, an X-band 1×3 substrate integrated waveguide (SIW) power divider design is presented. The designed SIW power divider provides equal amplitude with uniform phase distribution at the each output port. It has also a satisfactory operating bandwidth and low insertion loss. Moreover, the return loss is approximately 25 dB at the design frequency as shown in the EM simulation results.

A Dielectric Measurement-Based Design Approach for X-Band Applications on FR4 Substrate

Abstract: This paper presents a design approach based on the dielectric measurement of the FR4 substrate material at X-band. The approach mainly aims to increase the design accuracy by measuring the frequency depended dielectric constant and tangent loss values of the substrate material to be used in the fabrication, and including the obtained data as input to the design. In accordance with this purpose, FR4 is measured by using waveguide method and its electrical characteristics are obtained at X-band frequencies. To minimize the effect of design complexity, a microstrip line is designed, fabricated and measured utilizing ordinary simulation and PCB tools. The same design is re-simulated with the approach proposed in this paper and comparisons of all results validate the accuracy improvement of the proposed approach.

An Array Antenna for Both Long- and Medium-Range 77 GHz Automotive Radar Applications

Abstract: A novel array antenna with a flat-shoulder shaped radiation pattern is proposed as the transmitting antenna for 77 GHz automotive radar application. When it is used in an automotive radar comprising one transmitter and multiple identical receivers, it can meet the demands of both long-range and medium-range detections without switching the operation mode back and forth between the long-range radar scenario and the medium-range radar scenario. The proposed antenna concept is fully introduced to explain its mechanism. An unconventional array was synthesized to achieve the desired flat-shoulder shaped radiation pattern. Prototype of the proposed array antenna was also designed according to the array synthesis result, which consists of several linear series-fed patch arrays and a substrate-integrated waveguide power and phase distributing network. Fabrication and measurement of the prototype array antenna were completed, showing a good agreement between the measured data and the synthesized as well as the simulation results, thereby validating the design.

Generation of Millimeter-Wave Nondiffracting Airy OAM Beam Using a Single-Layer Hexagonal Lattice Reflectarray

Abstract: In this letter, a millimeter-wave (mm-wave) nondiffracting Airy orbital angular momentum (OAM) beam is experimentally demonstrated by using a single-layer hexagonal lattice reflectarray based on an Airy-OAM-phase modulation method. To reduce the design time, a near-field synthesis technique is used to theoretically analyze the nondiffracting characteristics of the Airy OAM beam. A hexagonal dual-resonance element, composed of a hexagon ring around a square patch, is employed in the reflectarray to provide a linear phase range of 360 $^{\circ }$ . The proposed reflectarray with a diameter of 45 cm is designed at 47 GHz, which can reshape the incident wave according to the superposition phase of the desired Airy beam and OAM beam. To validate our design, a prototype is fabricated and measured. The measured results agree well with the theoretical and simulated ones. The experimental results show that an Airy OAM beam with the mode of $+$ 1 is successfully generated from 44 to 49 GHz. The nondiffracting propagation distance is greater than 2.5 m (392 $\lambda _0$ ). Moreover, the measured results validate the autofocusing and self-healing properties of the Airy OAM beam.

Substrate-Integrated-Waveguide Power Dividers: An Overview of the Current Technology

Abstract: Power dividers are important components of microwave/millimeter wave (mm-wave) circuit design. This article provides a comprehensive review of the state-of-the-art substrate-integrated-waveguide (SIW) power dividers/combiners. SIW technology converts waveguide-like structures into planar form, compensates for the drawbacks of microstrip structures at higher-frequency circuit designs, and minimizes production complexity and costs compared to conventional waveguide structures. An overview of how traditional dividers have progressive adopted the SIW technique is presented and a comparative performance analysis of the divider types and practical paradigm show the future potential of SIW technology.

Triangular and Rectangular Lattices for Cosecant-Squared-Shaped Beam Reflectarrays

Abstract: In this letter, we design, analyze, simulate, fabricate, and measure the performance of reflectarrays capable of forming cosecant-squared beam shape. Due to their unique pattern and abrupt change, achieving a cosecant-squared beam is challenging. In our effort, we evaluate the efficacy of a commonly used rectangular lattice and compare it, for the first time, to a triangular lattice. Two linearly polarized reflectarrays, each with 20 λ 0 diameter in size, are fabricated and tested at 20 GHz. Through statistical methods, we quantify the gain agreement between the desired cosecant-squared mask and the measured beam patterns for both rectangular and triangular lattices. We have found that the rectangular lattice conforms better to the cosecant-squared mask at the design frequency of 20 GHz with a root-mean-square error of 6.27 dB. The triangular lattice conforms less, however, it does allow for an increase in gain bandwidth of 6.2% as compared to 4.5% for the rectangular lattice. Measured and simulated patterns are in a good agreement.

Compact SIW Power Divider with CSRRs for WLAN Application

Abstract: In this paper, the development of compact substrate-integrated-waveguide (SIW) power divider with complimentary-split-ring-resonators (CSRRs) is presented. The proposed SIW power divider is designed to work at S-band frequency for wireless local area network (WLAN) application. Two reversely arranged CSRRs incorporated into the SIW surface are intended to produce filtering effect of power divider useful for suppressing unwanted signals. Some parametric studies upon the physical parameters are carried out through simulation to obtain the compact design of power divider. Based on parametric studies, the proposed SIW power divider with CSRRs is then deployed on a 1.6 mm thick FR4 epoxy dielectric substrate with the size of $40\ \text{mm}\times 30\ \text{mm}$ . From the characterization, the proposed SIW power divider shows capability to work at the frequency of 2.4 GHz with the rejection rate more than 20 dB at the stopband area which is suitable for the desired application.