Compact full ku-band triplexer with improved e-plane power divider

An improved E-plane power divider for compact waveguide triplexers with large separation between channels is presented. The configuration of the divider aims to exploit the different behavior of the device for frequency bands with large separation, leading to a very asymmetric E-plane junction. H-plane filters with inductive windows are used for each channel, in order to obtain reduced insertion losses and lower sensitivity than in metal-insert E-plane filters. The resultant triplexer configuration is very compact, and its design is analyzed and optimized by Mode-Matching. The experimental results of a full Ku-band prototype for communications satellite systems show a very good agreement with the expected simulated response

Experimental verification of extraordinary transmission without surface plasmons

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.This letter provides an experimental demonstration of extraordinary transmission in a closed waveguide system loaded with an electrically small diaphragm. This is a situation where the standard surface plasmon polariton SPP theory does not apply. The theoretical explanation is then based on the concept of impedance matching. This concept has previously been applied by some of the authors to account for enhanced transmission in situations where surface plasmon theory can be used: periodic arrays of small holes or slits in flat metal screens. The experiment in this letter supports the impedance matching model, valid for when SPPs are present or not. © 2009 American Institute of PhysicsThe authors would like to acknowledge the support of this research by the Spanish Ministry of Science and Innovation and European Union Feder Funds Grant Nos. TEC2007-65376 and Consolider Ingenio 2010 CSD2008- 00066 and by the Spanish Junta de Andalucía Project No. TIC-25

Experimental verification of extraordinary transmission without surface plasmons

This letter provides an experimental demonstration of extraordinary transmission in a closed waveguide system loaded with an electrically small diaphragm. This is a situation where the standard surface plasmon polariton (SPP) theory does not apply. The theoretical explanation is then based on the concept of impedance matching. This concept has previously been applied by some of the authors to account for enhanced transmission in situations where surface plasmon theory can be used: periodic arrays of small holes or slits in flat metal screens. The experiment in this letter supports the impedance matching model, valid for when SPPs are present or not.Ministerio de Ciencia e Innovación TEC2007-65376, CSD2008- 00066Junta de Andalucía TIC-25

Diseño de filtros de canal elípticos y autoEcualizados en banda Ka implementados en guía rectangular plano H

En esta comunicación se presenta un proceso sistemático de diseño de filtros de canal elípticos y autoecualizados en guía de onda rectangular y configuración plano-H en banda Ka. Se pretende desarrollar una alternativa a la configuración clásica dual-mode en guía de onda circular, con el objetivo de abaratar el coste y simplificar el proceso de producción. Para validar la metodología presentada se ha diseñado, fabricado y medido un filtro de orden seis con dos ceros de transmisión a frecuencias finitas para mejorar el rechazo y dos ceros de ecualización para el retardo de grupo. Los resultados experimentales validan el método propuesto

Compact duplexing for a 680-GHz radar using a waveguide orthomode transducer

A compact 680-GHz waveguide orthomode transducer (OMT) and circular horn combination has been designed, tested, and characterized in a radar transceiver's duplexer. The duplexing capability is implemented by a hybrid waveguide quasi optical solution, combining a linear polarization OMT and an external grating polarizer. Isolation between the OMT's orthogonal ports' flanges was measured with a vector network analyzer to exceed 33 dB over a >10% bandwidth between 630 and 710 GHz. Calibrated Y-factor measurements using a mixer attached to the OMT ports reveal losses through the transmit and receive paths that sum to an average of 4.7 dB of two-way loss over 660-690 GHz. This is consistent with radar sensitivity measurements comparing the new OMT/horn with a quasi-optical wire grid beam splitter. Moreover, the radar performance assessment validates the OMT as a suitable compact substitute of the wire grid for the JPL's short-range 680-GHz imaging radar

Waveguide Bandpass Filters for Millimeter-Wave Radiometers

A fundamental requirement for most mm-wave heterodyne receivers is the rejection of the input image signal which is located close to the local oscillator frequency. For this purpose we use a bandpass filter, which for heterodyne receivers is also called an image rejection filter. In this paper we present a systematic approach to the design of a waveguide bandpass filter with a passband from 100 to 110 GHz and upper rejection bandwidth in the range from 113 to 145 GHz. We consider two non-tunable filter configurations: the first one is relatively selective with 11 sections (poles) whereas the second one is simpler with 5 sections. We used established design equations to propose an initial guess for the geometries of the filters, optimized the geometries, constructed the filters using two different milling methods, measured their transmission and reflection characteristics, and compared the measurements with numerical simulations. Measurements of both filters agree well with simulations in frequency response and rejection bandwidth. The insertion loss of the 11-pole filter is better than 10 dB and that of the 5-pole filter is better than 5 dB. The 11-pole filter has a sharper attenuation roll-off compared with the 5-pole filter. The upper out-of-band rejection is better than 40 dB up to 145 GHz for the 11-pole filter and up to 155 GHz for the 5-pole filter

Development of low loss waveguide filters for radio-astronomy applications

In this paper the modeling, fabrication and experimental characterization of a wideband band-pass filter operating in W-band (75-110 GHz) is presented. This new high-performance waveguide filter can have several potential applications and will particularly be relevant in radio-astronomy receivers. The classical direct coupled cavity-based synthesis is first used. Then, an efficient full-wave analysis based on the mode matching technique is carried out, leading to a tenth order all-pole filter design. Two different prototypes were fabricated using an accurate electroforming machining technique. A good agreement between simulation and measurements is obtained with negligible frequency shift and 15 dB return loss level. One should note the low level of insertion loss reported of about 0.4 dB within the band-pass, which is a critical parameter for low-noise receivers. © 2013 Elsevier B.V. All rights reserved

A micromachined dual-band orthomode transducer

In this paper, an orthomode transducer (OMT) for dual-band operation and optimized for stacked micromachined layers implementation is presented. The proposed design avoids the use of septums, irises, pins, or small features and minimizes the number of equal-thickness micromachined layers required. In this way, the micromachining fabrication is simplified, making the proposed design a very attractive candidate for high frequency applications and for low-cost batch production. A W-band dual-band design (one different polarization in each frequency band) with more than 10% fractional bandwidth for each band and 30% separation between bands is presented. In addition, proper routing and layered bends are designed for an optimum standard interfacing with the same orientation of the input/output ports. Two OMTs in a back-to-back configuration are fabricated using a thick SU-8 photo-resist micromachining process. A total of six stacked SU-8 layers, all of them with the same thickness of 635 μm, are used. The experimental results are coherent with the tolerance and misalignment of the process, validating the proposed novel OMT design

Waveguide manufacturing technologies for next-generation millimeter-wave antennas

International audienceSome recent waveguide-based antennas are presented in this paper, designed for the next generation of communication systems operating at the millimeter-wave band. The presented prototypes have been conceived to be manufactured using different state-of-the-art techniques, involving subtractive and additive approaches. All the designs have used the latest developments in the field of manufacturing to guarantee the required accuracy for operation at millimeter-wave frequencies, where tolerances are extremely tight. Different designs will be presented, including a monopulse antenna combining a comparator network, a mode converter, and a spline profile horn; a tunable phase shifter that is integrated into an array to implement reconfigurability of the main lobe direction; and a conformal array antenna. These prototypes were manufactured by diverse approaches taking into account the waveguide configuration, combining parts with high-precision milling, electrical discharge machining, direct metal laser sintering, or stereolithography with spray metallization, showing very competitive performances at the millimeter-wave band till 40 GHz. © 2021 by the authors. Licensee MDPI, Basel, Switzerland