T. W.Nuteson, "Electromagnetic Modeling of Quasi-optical Power Combiners." PhD Dissertation, December 1996.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....radar) millimeter wave LANs (60 GHz) cellular radio base stations, active missile seekers (94 GHz) and millimeter wave imaging (100 GHz) Work by Polarizer Input Output Polarizer Array Lens Array Oscillator Amplifier Lens Figure 1.2: Quasi optic power combining system. Nuteson et al. [1] resulted in an advanced method of moments approach combining spatial domain and spectral domain techniques to model quasi optical systems was formulated. Now with the addition of the geometry interface, user drawn structures can also be analysed. The moment method implementation was developed in ....

....the grid amplifier system in the quasi optical system. Once the appropriate Green s function is developed using the appropriate boundary conditions the MoM is simply evaluation of the integral equation (2.1) by e#cient numerical techniques. As an example we look at the work done by Heron et al. [1, 2] in developing a Green s function for the cavity resonator and the grid amplifier system by Nuteson et al. [3, 4, 6, 12,13] in the quasi optical system discussed above, this is important in terms of viewing how hierarchical modelling of a system is developed. A Dyadic Green s function for the ....

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T. W.Nuteson, "Electromagnetic Modeling of Quasi-optical Power Combiners." PhD Dissertation, December 1996.

....horn. The input and output are isolated by the polarizers. Simulation of such a system requires a tool that can model a physical structure, analyze complicated electromagnetic profile and produce data for use in a non linear circuit simulator. The Method of Moment simulator developed by Nuteson [5] can analyze the passive electromagnetic behavior of quasi optical systems. However the tool did not provide su#cient flexibility to model and simulate large structures. An addition of a graphical user interface was necessary for an integrated tools that can model a structure without making ....

....discretization. Method of moments (MoM) techniques solve an electric field integral equation for the unknown currents on the surfaces of the radiating elements. For a grid type structure the analysis involves use of mixed spectral and spatial domain techniques and appropriate Green s functions [5]. This improves the performance of the method when the basic cells are closely distributed in a system. Each MoM entry describes the reaction of one cell(the test) with another(the source) cell. In a planar structure the entries are identified for equal sized testing and observation cells, and ....

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T. W. Nuteson, Electromagnetic Modeling of Quasi-Optical Power Combiners,Ph.D. Dissertation, North Carolina State University, 1996.

....consequently the driving point impedances for all unit cells will not be the same as predicted by the unit cell approach. A full wave analysis of the whole structure is thus essential. Pioneering work was done here at North Carolina State University to model open cavity resonators and grid arrays [45 51]. Heron [46] developed a Green s function for the open cavity resonator. This Green s function is composed of two parts: resonant and nonresonant terms. The fields were represented using Hermite Gaussian wave beams. Nuteson [51] implemented the previously developed Green s function using the ....

....State University to model open cavity resonators and grid arrays [45 51] Heron [46] developed a Green s function for the open cavity resonator. This Green s function is composed of two parts: resonant and nonresonant terms. The fields were represented using Hermite Gaussian wave beams. Nuteson [51], implemented the previously developed Green s function using the method of moments. He also developed a dyadic Green s function for a lens system consisting of two lenses and an array of active devices as that shown in Fig. 2.11. The Green s function was derived by separately considering the ....

T. W. Nuteson, Electromagnetic Modeling of Quasi-Optical Power Combiners, Ph.D. Dissertation, North Carolina State University, 1996.

....R 1 is usually chosen as positive and R 2 is chosen as negative. An example for both addding a resistive augmentation circuit and phase shifting is seen in Figure 3.4 and 3.5. The frequency domain y 11 parameter of the cavity oscillator shown in Figure 3. 3 (obtained from a code written by Nuteson [35]) was transformed into time domain using IFFT command in MATLAB. Before the transformation, it was made sure that the frequency domain function was bandlimited. The procedure described above was applied to achieve this. Resistor values for the augmentation circuit were chosen as 50# and 30# for ....

T. W. Nuteson, Electromagnetic Modeling of Quasi-Optical Power Combiners,Ph.DDis- sertation, Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina, U.S.A., 1996.

....the antenna, the dielectric around the antenna and the structure of the carrier. Since the structure of the dielectric slab and the carrier are unchanged in the system, optimizing the size of the tapered antenna is the only option. By iteratively using the MoM method simulator developed by Nuteson [110], the tapered antenna is selected as 11 mm wide and 23 mm long, and the gap between tapers is selected about 50 m to have an input impedance close to 50# at the driving point. For a tapered antenna with this size, the simulated and measured S 11 is shown in Fig. 6.7 for the antenna sitting in air. ....

T. W. Nuteson, Electromagnetic Modeling of Quasi-Optical Power Combining, Ph.D. Dissertation, North Carolina State University, 1996. 126

....quasi optics are still not a reality. The lack of computer aided engineering tools has hindered the progress of the field. Further progress will require an increase in fundamental understanding as well as the ability to perform what if studies. A Method of Moment simulator was created by Nuteson [21] which generates a multi port impedance model of the passive section of a grid structure. The passive structure however needs to be linked to a nonlinear circuit solver to include the e#ect of the active devices in the grid system. It is also necessary to include excitation by impinging fields. ....

....models. The task of characterizing the structures has proved to be di#cult because the systems are usually several wavelengths in dimension. Some significant work has been done in the area of planar grid structures. Early models [6, 7] assumed the grid was infinitely large, but recent developments [21], have removed this assumption from the model. The literature review discusses modeling techniques for quasi optical grid amplifiers and oscillators. 2.2 Modeling of Quasi Optical Systems The grid oscillator presented in [6, 7, 9] was one of the early demonstrations of quasi optical power ....

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T. W. Nuteson, Electromagnetic Modeling of Quasi-Optical Power Combiners,Ph.D. Dissertation, North Carolina State University, 1996.

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