Altan M. Ferendeci

Coupling parameters for a side-coupled ring resonator and a microstrip line

A ring resonator side coupled to a microstrip line shows two close but distinct resonance peaks. These are identified as due to even-mode (magnetic field) and odd-mode (electric field) coupling. Equivalent circuit models for both cases have been proposed and coupling parameters are calculated using piecewise, coupled-line approximations. The calculated coupling coefficients for the two cases are compared with the experimentally-measured coupling coefficients and show very good agreement with the models used.

Broadband slotted spiral antennas with thin dielectric substrates

New broadband two arm Archimedean slot spiral antennas were designed and fabricated on very thin dielectric substrates with bottom ground planes. The antennas were designed for a vertically interconnected monolithically processed multilayer microwave integrated circuit. Two narrow-slot spiral antennas were fabricated and tested on a PCB first with a substrate thickness of 0.073 /spl lambda/g and 0.0056 /spl lambda/g, respectively. An operation bandwidth of 5.22% and 4.13% was achieved with good axial ratio and radiation pattern. Using the same design guideline, a 3/sup rd/ spiral antenna was then monolithically fabricated on a 68 /spl mu/m polyimide substrate (0.0038 /spl lambda/g) with bottom ground plane. The return loss was below -10 dB from 5.96-15.10 GHz with the lowest value of -24.88 dB at 7.13 GHz. Both simulation and measurement results have shown that performance of the spiral antennas on very thin substrates was improved when the slot width became comparable to the substrate thickness.

Vertically interconnected 3D module for conformal phased array antennas

The development of a basic X-band 3D-IC/MEMS microwave transmit module is investigated for the possibility of conformal phased array technology. An innovative approach using microelectronics and MEMS processing technologies is implemented to develop 3D-IC processing technology. This allows us to investigate the technology development needed for minimum module depth to enable distribution on any arbitrary surface. For the initial phase, as a demonstration vehicle, a basic passive transmit module is designed, fabricated and characterized at microwave frequencies.

Design methodology of microstrip lines using dimensional analysis

Dimensional analysis has been used to develop a new methodology in microwave integrated circuit design using microstrip lines. The analysis reveals a complete set of dimensionless products for the microstrip line. The dependencies between these products are established using the Pi theorem. Using commercial simulation tools and numerical fitting techniques, design formulas can be established. These design formulas calculate the desired microwave parameters, such as characteristic impedance, effective dielectric constants, and their frequency dependencies.

Conformal wide bandwidth antennas and arrays

Various widebandwidth antennas and challenges using these antennas for conformal phase arrays are presented. Problems that arise depending on the physical separation of the antennas and corresponding separations in terms of wavelength are discussed. For conformal placement of an antennas either as an individual antenna or as in an array configuration on any arbitrary surface may require very thin antenna structures. They should be processed preferably on flexible substrates so that they will conform to the surfaces without changing the surface geometry. Archimedean slotted spiral antennas that satisfy these requirements will be used to demonstrate problems associated with UWB phased arrays.

Equivalent circuit parameter extraction of microstrip coupling lines using FDTD method

A new algorithm, in conjunction with FDTD simulation, was developed to perform direct extractions of the equivalent circuit parameters for the coupled microstrip lines. The unit-length capacitance and inductance were derived from the FDTD results. The frequency-dependent microwave parameters such as phase velocity and the characteristic impedance do not show anomalous oscillation. Incorporated with the even-odd analysis, the scattering parameters of the coupled microstrip lines with a flexible coupling length can be calculated. The calculation results were found in good agreement with the measured scattering parameter data.

Net-shape processing of single-domain YBa2Cu3Ox for a novel high-Q millimeter wave resonator

Abstract Large single domain YBa 2 Cu 3 O x materials have been successfully fabricated with superb RF properties by employing the seeded-melt growth (SMG) method. Based on a new design, a cavity resonator has been constructed using the single-domain YBa 2 Cu 3 O x processed by SMG. The cavity consists of a hollow cylindrical cup covered by a polished plate, which operates in the TM 010 mode. All cavity parts are made of single-domain YBa 2 Cu 3 O x without any dielectric materials. The measured Q has reached a high value of 10200 at 18.4 GHz. Our experimental data show great promise in the development of RF components using single domain high temperature superconductors.

Two-Tone Intermodulation Distortion in High Tc Superconducting Thin Films.

Two tone intermodulation distortion (IMD) in High Tc YBCO superconducting films on LaAl2O3 substrates are experimentally studied. Experiments performed on straight through microstrip transmission lines indicate highly non-linear signal transmission characteristics for these films. In addition to the third harmonic, higher order intermodulation products are also observed even without using any resonant structures. The observed intermodulation distortion shows a minimum as a function of temperature for a given input power level. Close to Tc, in addition to a large increase in IMD, higher order intermodulation products also become appreciable. SEM photographs are used to relate the surface topology of the films and the grain boundaries to the observed IMD. Thin films deposited by various techniques are investigated.

Vertically interconnected thin substrate broadband slotted spiral antenna for conformal phased arrays

A new broadband 2-arm Archimedean slotted spiral antenna was designed and monolithically fabricated as an integral part of a 3D MMIC (Multilayer Microwave Integrated Circuit) T/R module. The antenna was processed on a thin polyimide substrate (68 um thick, 0.0038 /spl lambda/g) with a bottom ground plane. A wideband stripline balun was vertically interconnected to the antenna. Return loss of less than -10 dB was measured from 6 to 14 GHz with a lowest value of -49 dB at 10.8 GHz. Uniform broadside radiation pattern was obtained across the X-band with a gain variation of -12 /spl sim/ -1 dB. Both simulation and measurement results showed that performance of the slotted spiral antenna on a thin substrate was improved when the slot width became comparable to the polyimide substrate thickness. Also, reactive near field power distribution was measured for PCB slotted spiral antennas with similar designs. The low profile of the 3D MMIC T/R module enables the realization of the conformal phased array antenna systems.

TE modes of an axially multiple-grooved rectangular waveguide

A method is developed to calculate the TE mode fields and cut-off frequencies of an axially multiple-grooved rectangular (AGR) waveguide. A low frequency AGR waveguide is used as a part of a microwave cavity and the cut-off frequencies are measured in order to verify the analytically derived results. Excellent agreement between the measured and calculated values provide the basis for the design of waveguides for millimeter wave applications. The method has also been extended to a waveguide with multiple grooves cut into two of its broad wall parallel surfaces. >