Volkan Akan

Analyses of elliptical coplanar coupled waveguides and coplanar coupled waveguides with finite ground width

In this paper, the quasi-TEM characteristic parameters of elliptical coplanar coupled waveguides and coupled coplanar waveguide with a finite ground width configuration are presented and analyzed. Computer-aided design (CAD)-oriented fast, simple, and accurate analytic formulas are derived by using conformal mapping techniques, which provide satisfactory accuracy at microwave frequencies and lead to closed-form analytical solutions suitable for CAD software packages. The results for the odd- and even-mode characteristic impedance, effective dielectric constant, and coupling coefficient have been computed by these formulas. Good agreement between the present results and published results is observed. For the planar case, simulations have also been undertaken with Sonnet electromagnetic-circuit solver software. The computed results agree well with those of the simulation ones.

Conductor loss calculation of elliptical, cylindrical coplanar waveguides and coplanar waveguides with finite conductor thickness

In this paper, new and fast analytical formulations have been presented for conductor loss calculations of elliptical (ECPW) and cylindrical coplanar waveguide (CCPW) with finite conductor thickness. These expressions are derived using conformal mapping techniques (CMT) and the validity of them is established by comparing the numerical results in the literature. These comparisons indicate that for the same conductor thickness the conductor losses of elliptical and cylindrical coplanar waveguide are higher than the conductor losses of coplanar waveguide presented in (1). Calculation method developed in this study is an extension of the approximate technique proposed by Ghione (1).

Quasi-static solutions of multilayer elliptical, cylindrical coplanar striplines and multilayer coplanar striplines with finite dielectric dimensions - asymmetrical case

In this paper, fast, accurate, and simple analytic closed-form expressions are presented in order to calculate the quasi-TEM parameters of multilayer elliptical coplanar stripline (CPS), multilayer cylindrical CPS, and multilayer CPS, with finite dielectric dimensions by using conformal mapping techniques. The obtained computer-aided-design-oriented expressions are quite accurate and easy to apply in designing microwave integrated circuits and antenna applications. The results have also been compared with the ones of another conformal mapping method available in the literature and also confirmed analytically.

Communication subsystem of RASAT

RASAT will be the first satellite designed and manufactured in Turkey and it is planned to be launched in 2011. RASAT is a Low Earth Orbit (LEO) observation microsatellite with a mass of around 100 kg. The main purpose of this mission is remote sensing with use of a high resolution optical imager. The communication subsystem is one of the primary systems for Earth observation satellites. It is used for telecommand/telemetry signaling besides downlink data transfer. In RASATs communication subsystem, there are mainly five modules. For commissioning phase and as back-up of the downlink/uplink operations, Ultra High Frequency (UHF) / Very High Frequency (VHF) modules are used. The primary uplink is provided by the S-Band receivers and the primary downlink is provided by the S-Band transmitters on-board. X-Band transmitter module, which is designed and developed by engineers at TUBITAK-UZAY, is the experimental payload of RASAT communication subsystem.

Analysis of the relation between printed strip monopole and dielectric coated thin cylindrical monopole

Recently, printed type antennas are used widely in communication systems since they are low cost and produced easily. Firstly Hallen exposed the relation between thin cylindrical and strip monopole. Then this equivalent radius concept was applied to printed monopole antenna. In this paper relation between printed strip monopole and dielectric coated thin cylindrical monopole has been analyzed analytically and supported numerically.

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

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.

DESIGNS AND ANALYSES OF SOME RF/MICROWAVE PASSIVE ELEMENTS ON CYLINDRICAL CPWS

DESIGNS AND ANALYSES OF SOME RF/MICROWAVEPASSIVE ELEMENTS ON CYLINDRICAL CPWSV. AkanCommunication System GroupTUBITAK Space Technologies Research InstituteODTU KampusuInonu Bulvari, TR-06531, Ankara, TurkiyeM. DuyarRepublic of Turkiye Ministry of Industry and TradeAnkara, TurkiyeE. YazganDepartment of Electrical and Electronics EngineeringHacettepe UniversityTR-06800, Ankara TurkiyeM. BayrakFaculty of EngineeringDepartment of Electrical and Electronics EngineeringSelcuk UniversityKonya, TurkiyeAbstract—In this article, designs and analyses of several CCPW(Cylindrical CPW) discontinuities have been realized as microwavereactive elements. The quasi-TEM characteristic parametersof CCPWs have been obtained by CMT (Conformal MappingTechniques) which provide satisfactory accuracy at microwavefrequencies and lead to closed-form analytical solutions suitablefor CAD software packages. Then these discontinuities have beensimulated in CST Microwave Studio 2006 in order to obtaininductance, capacitance and also input impedance versus frequencyand physical dimensionsof the elements. The results show that CCPW

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

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.

Complex permittivity measurements of dielectrics for space antenna radome and substrates in X-band

A variety of material measurement systems based on transmission/reflection line method are available to characterize the dielectric properties of materials by extracting the S-parameters using a Vector Network Analyzer (VNA). A waveguide material measurement facility based on transmission/reflection line method has been developed in-house in order to accurately deduct relative dielectric permittivity and tangent loss values of dielectric materials used for manufacturing antenna radome and substrate. In this paper, the experimental measurements of VESPEL, PTFE (Teflon), and RO5880 have been realized in X-band (8–12 GHz) with a very low standard deviation.

A compact filter using substrate integrated waveguide technology

This paper presents a bandpass filter structure using substrate integrated waveguide technology, which is considered as a reliable and cost-effective solution to replace bulky waveguide component in microwave and millimeter wave systems. The substrate integrated waveguide is synthesized by using two rows of conducting cylinders embedded in a dielectric substrate that electrically connect two parallel metal plates. The additional inductive posts provide reactive loading to implement bandpass characteristics. According to the full EM simulation results, the bandpass filter exhibits an insertion loss of about 1.4 dB in the 7.3 GHz-7.7 GHz band.