The overall field theory designs of two types of quasi-planar millimeter-wave multiplexers utilizing low-cost, low-insertion-loss printed metallic E-plane filters are described Very compact components are achieved by using E-plane filters printed on a common metal sheet which is directly integrated in the septate sections of an E-plane n-furcated split-block waveguide housing The second configuration proposed extends the useful principle of waveguide H-plane slit-coupled manifold multiplexers to the case of millimeter-wave printed metallic E-plane filters Based on the model scattering matrix description of suitable key building blocks, the rigorous simulation technique used comprises the complete multiplexer structure including the E-plane transformer or iris elements, the waveguide E- or H-plane junctions, and the filter sections >

Rigorous field theory design of millimeter-wave E-plane integrated circuit multiplexers

The rigorous field-theory-based design of a class of rectangular waveguide slit-coupled H-plane T-junction diplexers utilizing E-plane metal-insert filters is described. The filter elements allow low-cost manufacturing by accurate and inexpensive metal-etching techniques. The design method is based on a field expansion in suitably normalized eigenmodes which yields the modal scattering matrices of the three key building blocks used: the E-plane metal-insert section, the H-plane iris discontinuity, and the H-plane T. The theory includes the finite thickness of the diaphragms as well as the higher order mode interaction of all discontinuities within the complete diplexer structure. Computer-optimized design data for diplexer examples in Ku-band (12-18 GHz) and E-band (60-90 GHz), designed for more than 23-dB common port return losses, are given. The theory is verified by measured results for a five-resonator Ku-band diplexer. >

Computer-aided design of slit-coupled H-plane T-junction diplexers with E-plane metal-insert filters

The feasibility of building high-temperature superconducting (HTS) hybrid-coupled multiplexers and diplexers employing filters with asymmetrical frequency characteristics is demonstrated. The design of pseudo-interdigital filters with improved skirt performance is discussed. Experimental and theoretical results are presented for superconducting filters, hybrids, and a fully integrated C-band diplexer. It is noted that the extra coupling which exists between nonadjacent resonators in pseudo-interdigital filters may be used to improve the rejection performance on the high-frequency skirt. Filters with such rejection performance are suitable for use in the design of HTS hybrid-coupled multiplexers and diplexers. The experimental results reported here for superconducting filters, hybrids and the fully integrated C-band diplexer demonstrate the possibility of building such components with no tuning elements. >

Design of hybrid-coupled multiplexers and diplexers using asymmetrical superconducting filters

A novel design of W-band (75-110 GHz) noncontiguous diplexers is described. The common port of the diplexer is fed by suspended probe transitions which are suitable for wide-band applications. The circuit is printed on a single substrate and easily assembled in a split-block housing. The measured insertion loss at the passbands is about 1 dB. The calculated frequency response of a diplexer is in good agreement with the measurement.

Millimeter-Wave Diplexers with Printed Circuit Elements

A waveguide diplexer is introduced where optimised low-insertion-loss metal insert filters are directly integrated in the E-planes of the T-junction arms. The filters are designed by the exact method of field expansion into suitable eigenmodes which takes the influences of higher-order-mode interaction and finite thickness of the inserts into account. Computer optimised design data are given which provide a metaletching technique for reliable low-cost production. Measured minimum passband insertion losses of an R120-waveguide diplexer prototype are about 0.8 dB at 10.4 GHz, and 0.5 dB at 11.2 GHz. The stopband attenuation at 10.8 GHz is about 48 dB.

Waveguide E-plane integrated-circuit diplexer

Work with millimeter-wave components using printed-circuit techniques has led to the successful development of multiplexers that are compatible with low-cost fabrication and packaging techniques. This paper will describe a 26 to 42-GHz multiplexer exhibiting 1.2 to 2.8 -dB insertion loss over a 4-GHz channel passband and a 45-dB rejection bandwidth of less than 8 GHz. This multiplexer uses a channel-dropping filter technique that splits the band into 4-GHz subbands (channels). Each channel-dropping filter consists of dual band-pass filters separated by a pair of 3-dB directional couplers. Fabrication costs are kept low by using chemically-milled broadwall couplers and E-plane filter resonators. A series of normalized filter design nomograph's have been generated. Measured multiplexer performance will be presented.

K.D. Breuer

Papers

A Low Cost Multiplexer for Channelized Receiver Front Ends at Millimeter Waves