The concept of the conventional coupling matrix is extended to include designs of dual- and triple-band filters. The multiband response is created by either placing transmission zeros within the bandwidth of a wideband filter or using higher order resonances. Realizable topologies both in planar and waveguide technologies can be imposed and associated coupling coefficients enforced during optimization. The design process is verified by measurements and comparison with results of commercially available field solvers

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Coupling-Matrix Design of Dual and Triple Passband Filters

The present invention provides an improved single antenna system that allows reception of RF energy at multiple frequencies. In one embodiment, the antenna is implemented as a multi-beam, multi-feed antenna having a primary reflector fitted with a dual mode feed tube and a switchable LNB that supports both Ka band and Ku band reception. In another embodiment, the antenna is implemented as a multi-beam, multi-feed antenna having a primary reflector fitted with a feed horn and a LNB that is capable of providing movement such that the feed horn with the LNB is at a focal point with the primary reflector for both Ka and Ku band reception. In another embodiment, the antennae is implemented as a multi-beam, multi-feed antenna having a primary reflected fitted with a feed horn assembly and a switchable LNB that supports both Ka band and Ku band reception.

Multi-band antenna system for satellite communications

Following a brief review of different types of multiplexer configurations, a systematic design approach has been outlined for the design of manifold-coupled multiplexers. The piecewise approach, optimizing parts of the multiplexer separately in repeated cycles while converging upon an optimal solution, has proved to be very effective for most practical applications. The technique is readily applicable to manifold multiplexers incorporating an arbitrary number of channels, regardless of their bandwidths and channel separations. There are no restrictions on the design and implementation of channel filters onto the manifold; they may be asymmetric, and may incorporate transmission zeros, group delay equalization zeros, or both. The manifold itself is a transmission line, be it a coaxial line or a rectangular waveguide or some other low-loss structure. The costly EM simulation is used economically on manifold junctions and channel filters through the use of space-mapping optimization techniques, where EM-based simulators are used to fine-model each multiplexer channel and coupling matrix representation is used to coarse-model the performance. Fine details such as tuning screws may be included in the design process. This design procedure takes into account the effects of dispersion and spurious modes and, as a result, the overall design and final tuning time can be significantly reduced.

Design of manifold-coupled multiplexers

Single-layer, wideband, and low-loss corporate-feed networks for slot antenna arrays are described. The antenna is built using ridge gap waveguide technology, formed between two parallel metal plates without the requirements of electrical contact between these plates. The corporate-feed network is realized by a texture of pins and a guiding ridge in the bottom plate, and the radiating slots are placed in the smooth top plate. The paper describes two test antennas: a 4 $\,\times\,$ 1 linear slot array and a 2 $\,\times\,$ 2 planar slot array. Both have been fabricated and tested at Ku- band. The linear array shows more than 20% bandwidth and the 2 $\,\times\,$ 2 array shows a bandwidth of 21% for 10-dB return loss. There are good agreements between measured and simulated patterns for both antennas. Measured gain for the planar array is found to be at least 12.2 dBi over 12–15 GHz band.

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Wide-Band Slot Antenna Arrays With Single-Layer Corporate-Feed Network in Ridge Gap Waveguide Technology

A new design for single-channel waveguide rotary joints for high-power applications is presented. In order to obtain correct signal phase conditions along the ring and, at the same time, reduce the diameter of the rotary joint, tapered ridged waveguide sections are introduced. Design guidelines with respect to general transmission characteristics, H-plane aperture couplers, and ridge waveguide analysis are presented. Measurements of a 9.05-GHz prototype show less than 1-dB insertion loss over a 250-MHz bandwidth and, hence, verify the design concept.

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Compact single-channel rotary joint using ridged waveguide sections for phase adjustment

This book delivers an in-depth examinations of the three basic field-theoretical methods used for the design aid of different waveguide components You'll find CAD algorithms, examples of their applications, and operational principles of various components used in antenna feed systems

Waveguide Components for Antenna Feed Systems: Theory and CAD

A fast and efficient radial mode-matching technique (RMMT) is applied to the analysis and design of components in circular ridge waveguide technology. Five different structures are investigated with respect to their performance as filters and polarizers. For fast computation, pie-shaped metal ridges and septa are assumed to better fit the cylindrical coordinate system. In practice, the pie-shaped structures are approximated by rectangular cross-section metal inserts. The validity of this approximation is investigated by comparing with measurements and finite-element analysis. It is found that for thin etchable inserts, the measured filter response is in excellent agreement with the theoretical prediction and that for polarizers, the axial ratio response is not particularly sensitive to the ridge shape. Differences between computed and measured results occur only at return loss and isolation levels beyond 25 dB. A central processing unit time comparison with HFSS (4.0) results in a 10-min versus 3-h advantage in favor of the RMMT.

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Analysis and design of circular ridged waveguide components

Impedance-matched ferrite-loaded waveguide nonreciprocal phase shifters are designed using the method of field expansion into eigenmodes, which includes higher order mode interaction between the step discontinuities. Computer-optimized Ku -band ferrite stepped design examples, of 45° and 90° nonreciprocal differential phase shifts, attain typically about 2° phase error and less than -25 dB input reflection within a bandwidth of about 5 percent. Compact designs are achieved by thicker uniform ferrite slabs with dielectric transformer sections at each end. The theory is verified by comparison with available results from measurements and other methods.

http://www.ece.uvic.ca/~jbornema/Journals/022-87mtt-uab.pdf

Field Theory Design of Ferrite-Loaded Waveguide Nonreciprocal Phase Shifters with Multisection Ferrite Or Dielectric Slab Impedance Transformers

An analysis and design concept for the dual-band orthomode junction is presented. The centerpiece of the design is a waveguide six-port cross junction. Its modal analysis is verified by measurements available in the literature. After introducing appropriate symmetry planes for the orthomode junction, a principal design approach is outlined. The entire procedure is demonstrated for a K/Ka-band design example. The final design is compared to results from the commercial software package HFSS and is found to be in good agreement.

Modal analysis and design of the dual-band orthomode junction

The paper presents an efficient CAD algorithm for the design of waveguide front-end diplexers. Three different types of junctions can be employed: E-plane T-junction, H-plane T-junction and E-plane bifurcation. Channel filter configurations currently include — but are not limited to — waveguide stub filters and inductive-iris filters. The diplexer design is performed in three basic steps: synthesis, analysis and optimization. In order to improve the computing efficiency of the design algorithm, highly accurate transmission line models are used in the initial component design and optimization stages. The final optimization and the analysis of the entire diplexer makes use of a full-wave mode-matching model, which can include waveguide transformers at all ports. The CAD routine is verified against measurments, and excellent agreement between predicted and measured results is obtained.

J. Uher

Papers

Waveguide Components for Antenna Feed Systems: Theory and CAD

Analysis and design of circular ridged waveguide components

Field Theory Design of Ferrite-Loaded Waveguide Nonreciprocal Phase Shifters with Multisection Ferrite Or Dielectric Slab Impedance Transformers

Modal analysis and design of the dual-band orthomode junction

Efficient full-wave CAD of waveguide diplexers