Antipodal Finline Research Articles

Polymer electro-optic devices for integrated optics

Recent advances in polymer electro-optic polymers and in fabrication techniques have made possible advances in polymer optical guided wave devices which bring them much closer to system ready. The processing of a new thermal set FTC polymer and its incorporation into a high-frequency, low- V π optical amplitude modulator are reviewed. The design and fabrication of 100 GHz modulators and their integration with rectangular metal waveguides using an anti-podal finline transition with a flexible Mylar substrate is discussed. High-speed polymer modulators with balanced outputs and the in situ trimming of the output coupler is described. More complex guided wave devices using polymers are demonstrated by the photonic rf phase shifter. Techniques for integrating both passive and active polymers into the same optical circuit without the need for mode matching is presented and demonstrated. To reduce the V π of a polymer amplitude modulator to 1 V or under, a technique of constant-bias voltage is demonstrated. Finally, a technique to directly laser write electro-optic polymer devices is reviewed.

Broadband 230 GHz finline mixer for astronomical imaging arrays

The authors report the successful operation of an antipodal finline quasi-particle SIS mixer at 230 GHz. The mixer is fed by a waveguide diagonal horn and uses planar circuit technology and integrated tuning. The mixer is tested over the frequency range 213–265 GHz and a receiver noise temperature of ~60 K DSB over the whole of this range is obtained. This work has shown that superconducting finline mixers have low noise and are easy to manufacture, and are therefore suitable for large-format imaging arrays.

Attenuation and propagation in various finline structures

The theory and numerical results of the asymmetric single and coupled bilateral and unilateral finlines and arbitrary antipodal finline considering the attenuation of the substrate are presented. Results are given to the complex propagation constant. The full wave analysis of the Transverse Transmission Line — TTL method is used in the FTD. Applying the moment method the complex propagation constant, including the attenuation constant and the phase constant, are obtained. The effective dielectric constant, ɛeff,, and the characteristic impedance are also calculated. The results are compared with the references, and news results are presented for these parameters.

A WH/GSMT-based full-wave analysis for planar transmission lines embedded in multilayered dielectric substrates

A new full-wave analysis method, referred to as the WH/GSMT, is developed to solve multilayered planar transmission line problems. First, the scattering of an obliquely incident parallel plate mode (PPM) by a PEC half plane embedded in a multilayered isotropic dielectric substrate within a PEC parallel plate region is analyzed via the Wiener-Hopf (WH) technique. The solution is then incorporated into the generalized scattering matrix technique (GSMT) to find the (complex) propagation constant and characteristic impedance of the planar transmission lines. The lateral power leakage is taken into account rigorously in the WH/GSMT. Numerical results including the microstrip line, conductor-backed slotline, coupled microstrip lines, and antipodal finlines are presented along with a discussion of the advantages/disadvantages of this method. >

Parametric interactions in high-Tc superconducting step edge junctions at X-band

We have fabricated and tested both single junctions and series arrays of YBCO step edge junctions for four photon parametric effects at X band as a first step in developing a parametric amplifier at 60 GHz. The series array of 25 junctions at 10.3 Ghz shows a 10 dB increase in reflected signal power as the pump power is increased, while the single junction at 12.2 GHz indicates a 2 dB change. The reflected power at the characteristic idler frequency of 2ω p-ω s is evidence of true Josephson junction parametric interaction. We are currently investigating the use of thallium based films at 60 GHz which offer a broader range of operating temperatures than does YBCO. Our design for a parametric amplifier at V band is a combination of microstrip based series arrays of junctions and an antipodal finline transition.

Analysis of waveguide‐to‐microstrip transition

AbstractThe analysis method for the antipodal finline waveguide‐to‐micro‐strip transition is presented in the article. The revised empirical expressions for the transition from nonoverlapped antipodal finline to overlapped one are given. We design a Ka‐band broadband waveguide‐to‐microstrip transition using this method. The experimental results have a good agreement with the theoretical ones.

Analysis of fin-line tapers and transitions

A design method for tapered transitions between arbitrary types of fin line (unilateral, bilateral, antipodal fin lines and, as special case, rectangular waveguide) is presented which optimises the profile of the slot width itself. The procedure, which can easily be implemented on a desk-top computer, is based only on the knowledge of the propagation constant of the fundamental mode. Results are presented for tapers between various fin lines.

An Accurate, Unified Solution to Various Fin-Line Structures, of Phase Constant, Characteristic Impedance, and Attenuation

The analysis of several fin-line configurations (unilateral fin-line, bilateral fin-line, antipodal fin-line, and coupled fin-lines) has been completed accurately. In this unified method, propagation constant is achieved via the generalized spectral domain technique where the basis functions for the bounded and unbounded fields are chosen to be trigonometric functions and Legendre polynomials, respectively. The conduction loss and dielectric loss solution for the first time are found through a perturbation method. The conductor loss so derived is believed to be sufficiently accurate for practical purposes. Characteristic impedances of these transmission lines using tentative definitions have been presented. The CPU time on an IBM 360/65 for calculation of the mentioned parameters does not exceed five seconds if the fourth-order solution in the spectral analysis gives the required accuracy. The programs are also capable of detection of higher order modes.

Closed-form approximations for fin-line eigenmodes

The characteristic equations for bilateral, unilateral and antipodal fin lines are formulated in a convenient form for an approximate evaluation. It is shown that the eigenvalues for all higher-order modes can be calculated from closed-form expressions provided that the two lowest eigenvalues are known. Dispersion relations are developed which are equivalent to those for rectangular waveguides. The analysis also comprehends a simple evaluation of the field configurations of all hybrid eigenmodes. The approximate formulas are checked against exact numerical calculations, the agreement being excellent.

Broadband RF-coupling to thin-film Josephson and SIS devices

The fabrication of a planar fin-line circuit for rf-coupling to Josephson tunnel junctions and SIS devices is reported. E-field coupling is achieved by means of tapered transitions from a rectangular waveguide to a fin-line and from this line to the active device. Its low impedance can be matched by an antipodal fin-line with a fin-separation in the μm-range. Circuit parameters have been determined for Nb-Pb-devices mounted in a split Ka-band waveguide. Measurements were performed in the frequency range from 33 GHz and 38 GHz. Mismatches as low as 10 dB have been observed.

Fin-line dispersion

The dispersion of different fin-line geometries is calculated by applying Galerkin's method to the electric fields in the slot interface. The antipodal fin line is shown to be of high interest, since its wave impedance can easily be varied from very low to high values.