Richard J. Cameron
COM DEV International
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Featured researches published by Richard J. Cameron.
IEEE Transactions on Microwave Theory and Techniques | 1999
Richard J. Cameron
Methods are presented for the generation of the transfer polynomials, and then the direct synthesis of the corresponding canonical network coupling matrices for Chebyshev (i.e., prescribed-equiripple) filtering functions of the most general kind. A simple recursion technique is described for the generation of the polynomials for even- or odd-degree Chebyshev filtering functions with symmetrically or asymmetrically prescribed transmission zeros and/or group delay equalization zero pairs. The method for the synthesis of the coupling matrix for the corresponding single- or double-terminated network is then given. Finally, a novel direct technique, not involving optimization, for reconfiguring the matrix into a practical form suitable for realization with microwave resonator technology is introduced. These universal methods will be useful for the design of efficient high-performance microwave filters in a wide variety of technologies for application in space and terrestrial communication systems.
IEEE Transactions on Microwave Theory and Techniques | 1992
Chandra M. Kudsia; Richard J. Cameron; Wai-Cheung Tang
The evolution of microwave filters and multiplexers for space application is described. The many advances are described within the context of the design of the overall communication subsystem. Emphasis is placed on the multipaction and passive intermodulation (PIM) considerations in designing high-power multiplexers. The impact of microwave filter technology in the channel characterization of satellite systems is described. The future directions of research and development are briefly discussed. >
international microwave symposium | 2005
Richard J. Cameron; Ming Yu; Ying Wang
This paper presents new ideas for the design and implementation of microwave filters with single and dual stopbands. They can be realized with waveguide, coaxial, dielectric resonators, or in a planar technology. The new methods represent an advance over present methods in that the resonators are direct coupled, thus avoiding the need for transmission line phase lengths between resonator stubs that tend to degrade performance due to their dispersion and are difficult to adjust during tuning. Three bandstop (BS) configurations are presented. The first will accommodate even or odd characteristics and also asymmetric responses, although some negative or diagonal cross-couplings will be needed. The second resembles the cul-de-sac configuration for bandpass filters and needs no diagonal or negative couplings even for asymmetric characteristics. The third is an application of the cul-de-sac synthesis technique to dual-band bandstop (DBBS) filters. All these BS designs are very similar to regular bandpass filters in their design and realization. The design of a DBBS filter is presented and compared with an equivalent bandpass filter to demonstrate its advantages. Finally, the simulated and measured results of a fourth-degree BS filter design in the novel cul-de-sac configuration are presented.
IEEE Transactions on Microwave Theory and Techniques | 2003
Ming Yu; Wai-Cheung Tang; Alastair Malarky; Van Dokas; Richard J. Cameron; Ying Wang
This paper presents a novel adaptive predistortion technique for general cross-coupled microwave/RF filters with improved insertion loss and group-delay equalization. The method enables many potential applications of an almost abandoned technique, and permits a lower Q implementation technology to emulate the performance of a higher Q filter. 10-4-4 filters were built and tested at C- and Ku-band to verify the validity of the new method. The impact to satellite communication channels was also analyzed. Another novel concept of over-predistortion was proposed and evaluated and should lead to significant improvement for applications such as satellite transponder input multiplexers, where insertion loss can be traded off for in-band flatness, mass, volume, and even overall system performance.
international microwave symposium | 2005
Richard J. Cameron; Jean-Charles Faugère; Fabien Seyfert
In this paper a new approach to the synthesis of coupling matrices for microwave filters is presented. The new approach represents an advance on existing direct and optimization methods for coupling matrix synthesis in that it will exhaustively discover all possible coupling matrix solutions for a network if more than one exists. This enables a selection to be made of the set of coupling values, resonator frequency offsets, parasitic coupling tolerance etc that will be best suited to the technology it is intended to realize the microwave filter with. To demonstrate the use of the method, the case of the recently – introduced ‘extended box’ (EB) coupling matrix configuration is taken. The EB represents a new class of filter configuration featuring a number of important advantages, one of which is the existence of multiple coupling matrix solutions for each prototype filtering function, eg 16 for 8th degree cases. This case is taken as an example to demonstrate the use of the synthesis method – yielding one solution suitable for dual-mode realization and one where some couplings are small enough to neglec
international microwave symposium | 2007
S. Cogollos; Richard J. Cameron; Raafat R. Mansour; Ming Yu; V. E. Boria
The synthesis and design of filters with nonresonating nodes (NRN) is applied to a practical case of hard requirements, with the aim of demonstrating the practical limits of such technique. An eight pole full inductive waveguide filter for space applications has been designed using a distributed model with frequency dependent inverters. Furthermore, the filter has been slightly tapered to scatter spikes due to the NRN unwanted resonances following a minimum dispersion criterion and maximum bandstop free of spurious. This feature has been incorporated into the distributed model showing down-to-earth designs from the very beginning of the design process.
international microwave symposium | 2000
Apu Sivadas; Ming Yu; Richard J. Cameron
A method for computing the peak resonator voltages inside a bandpass filter and multiplexer is introduced based on the general cross-coupled lumped element prototype network of a filter. In this method, the resonator voltages are computed based on the circuit model and are shown to be related to the peak filter cavity voltages through an appropriate scale factor. Being circuit theoretical the method is simple and is considerably faster than techniques based on rigorous field theoretic tools. The proposed method is verified using direct calculation of voltages by commercial FEM software. This voltage estimation procedure would considerably simplify multipaction and power handling studies of critical filter based structures.
IEEE Transactions on Microwave Theory and Techniques | 2013
Hai Hu; Ke-Li Wu; Richard J. Cameron
A stepped circular waveguide dual-mode (SCWDM) filter is fully investigated in this paper, from its basic characteristic to design formula. As compared to a conventional circular waveguide dual-mode (CWDM) filter, it provides more freedoms for shifting and suppressing the spurious modes in a wide frequency band. This useful attribute can be used for a broadband waveguide contiguous output multiplexer (OMUX) in satellite payloads. The scaling factor for relating coupling value M to its corresponding impedance inverter K in a stepped cavity is derived for full-wave EM design. To validate the design technique, four design examples are presented. One challenging example is a wideband 17-channel Ku-band contiguous multiplexer with two SCWDM channel filters. A triplexer hardware covering the same included bandwidth is also designed and measured. The measurement results show excellent agreement with those of the theoretical EM designs, justifying the effectiveness of full-wave EM modal analysis. Comparing to the best possible design of conventional CWDM filters, at least 30% more spurious-free range in both Ku-band and C-band can be achieved by using SCWDM filters.
international microwave symposium | 2008
S. Cogollos; V. E. Boria; Richard J. Cameron; Raafat R. Mansour
A complete design procedure of microstrip filters with high electrical performance using non-resonating nodes (NRN) is proposed. Such design procedure, based on a distributed model with frequency dependent inverters, allows the flexible allocation of transmission zeros in order to obtain high selectivity filtering responses, as well as the reduction of their frequency sensitivity. We have successfully validated this novel strategy with the design of a high performance microstrip filter, making use of a low cost substrate (i.e. with a low dielectric constant) and considering losses effects.
international microwave symposium | 2005
Ming Yu; Richard J. Cameron; David R. Smith; Van Dokas; Ying Wang
This paper presents a symmetric realization for a predistorted bandpass filter using a general cross-coupled resonator structure. The new method enables much simpler conversion from an existing filter design without predistortion. Hence both design and tuning efforts are reduced. A 10-4-4 dielectric resonator filter was built to verify the validity of the new method. The filter, coupled with an input circulator and output isolator was tested over temperature to validate the suitability for practical applications such as satellite transponder input multiplexers. Index Terms — Predistortion, bandpass filters, filter synthesis, microwave filter.