A 10-way power divider based on a transducer and a radial junction operating in the circular TM01 mode

This work presents a 10-way Ku-band power divider using a mode transducer and a radial junction connected by an overmoded circular waveguide operating in the TM 01 mode. The circular symmetry of this mode has been exploited to obtain a power divider with the rectangular output ports radially distributed along the broad wall of the waveguides in H-plane configuration. This topology provides the same amplitude and phase for all the output ports. At the same time, a compact profile has been obtained, introducing a simple manufacturing for the two components of the divider. The first component is a mode transducer converting the TE 10 mode in the rectangular waveguide to the TM 01 mode in the circular waveguide. It is based on a novel topology providing a very high purity in the mode conversion with an attenuation for the other propagating mode, the TE 11c , higher than 60 dB. The second component is a 10-way radial junction that must work under the excitation of the TM 01 , whose special features, since this mode is not the fundamental one of the circular waveguide, will be highlighted. The final design has been validated with an experimental prototype, proposing a manufacturing based on four simple parts. This has been the key to obtain an experimental prototype with specifications in the state-of-the-art. The measured efficiency is better than 96.5% in a 16.7% relative frequency bandwidth from 11 GHz to 13 GHz, with return losses better than 25 dB in the common port. The measured difference between the signals at the output ports of the prototype is ±0.3 dB for the amplitudes and ±0.45° for the phases. A comparison of the obtained results with another divider based on the TE 01 mode shows the potential of the presented design for becoming an alternative to the more extended TE 01 -based power dividersThis work was supported by the Spanish Government through the Agencia Estatal de Investigacion, Fondo Europeo de Desarrollo Regional (AEI/FEDER, UE), under Grant TEC2016-76070-C3-1/2-R (ADDMATE

Design of a Ku-Band High-Purity Transducer for the TM01 Circular Waveguide Mode by Means of T-Type Junctions

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksA new mode transducer for converting the TE10 rectangular waveguide mode to the TM01 circular waveguide mode is presented. The novel topology is based on two T type junctions with in-phaseexcitation at their input rectangular ports. The first one is an H-plane T-junction in rectangular waveguide. The second one differs from the standard E-plane T-junction in the excitation, which is carried out by modes excited with fields having the same in-phase polarization at the input rectangular ports, and has the output port in circular waveguide. This configuration exploits the symmetry of the modes under consideration to achieve a high-purity conversion, controlling the propagating circular waveguide TE11 mode to a maximum level of -42 dB in the whole operation band. The design bandwidth is 2 GHz centered at 12 GHz with a return loss level higher than 28 dB. In addition, the transducer can be divided in a main body plus a cover for easing the manufacturing. In order to verify the proposed geometry, a back-to-back arrangement has been measured connecting two similar aluminum transducers with four different angles between their rectangular ports (0◦, 45◦, 90◦, and 180◦). The excellent experimental results validate the novel transducer with a measured converting efficiency higher than 98.2% in a 16.7% relative frequency bandwidthThis work was supported by the Spanish Government (Agencia Estatal de Investigación) under Grant (ADDMATE) TEC2016-76070-C3-1/2-R (AEI/FEDER/UE

Jäähdytetty 90 GHz:n VLBI-vastaanottimen etupää

A cooled 90 GHz VLBI-receiver front end is discussed in this thesis. Very Long Baseline Interferometry (VLBI) is a method in which the signals received by several radiotelescopes, located even on different continents, measuring the same object are combined in order to achieve a higher angular resolution and imaging capability. The focus of this work is on the design of passive waveguide components. A corrugated feed horn, a polariser, a directional coupler, a power divider and a band-pass filter were designed. Their simulated properties are presented, and from the part of the power divider and the band-pass filter, the prototypes of which were available before the writing of this thesis, a comparison to actual devices is carried out. The prototypes were measured at room temperature. The heart of the front end is two lownoise preamplifiers provided by DA-Design Ltd. They are based on indium-phosphide high electron mobility transistors (InP HEMTs), the structure and operating principle of which are reviewed. A measurement procedure for obtaining the gain and noise characteristics at room and cryogenic temperatures is described, and the measurement results are presented from the part of one amplifier. A 20 percent operating bandwidth was set as a goal. Expect for the polariser, the simulated performance of all the components was satisfactory for such a bandwidth. Axial ratio and isolation requirements of 0.5 dB and 30 dB limited the relative bandwidth of the polariser to about 13 percent. The properties of the prototype power divider followed the simulations closely, the power split being equal and the return loss better than 18 dB. Even though the width of the pass-band of the prototype filter was the desired one, the pass-band had shifted about 1 GHz towards lower frequencies. The average insertion loss was 0.8 dB. The average noise temperature and gain of the low-noise preamplifier were 60 K and 53 dB at a temperature of 20 K.Tässä työssä käsitellään 90 GHz:n VLBI-vastaanottimen jäähdytettyä etupäätä. Pitkäkanta interferometria, eli Very Long Baseline Interferometry (VLBI), on menetelmä, jossa useiden, jopa eri mantereilla sijaitsevien, samaa kohdetta havaitsevien radioteleskooppien mittaustulokset yhdistetään suuremman erotuskyvyn ja kuvantamisominaisuuden saavuttamiseksi. Työn painopiste on passiivisten aaltoputkikomponenttien suunnittelussa. Suunniteltuja komponentteja ovat korrugoitu syöttötorvi, polarisaattori, suuntakytkin, tehonjakaja ja kaistanpäästösuodatin. Komponenttien simuloidut ominaisuudet esitetään, ja koska tehonjakajasta ja suodattimesta ehdittiin teettää prototyypit ennen työn valmistumista, niistä saatuja mittaustuloksia verrataan simuloituihin. Prototyypit mitattiin huoneenlämpötilassa. Kaksi DA-Design Oy:n toimittamaa vähäkohinaista esivahvistinta muodostaa etupään ytimen. Ne perustuvat korkean elektroniliikkuvuuden transistoreihin, joiden substraattina on käytetty indium-fosfidia (indium-phosphide high electron mobility transistor, InP HEMT). Transistorien rakenne ja toimintaperiaate käydään pääpiireittäin läpi, ja mittausmenetelmä sekä huoneenlämpötilassa olevan että 20 kelviniin jäähdytetyn vahvistimen kohinalämpötilan ja vahvistuksen selvittämiseksi kuvataan. Mittaustulokset esitetään toisen vahvistimen osalta. Kahdenkymmenen prosentin toimintakaista asetettiin tavoitteeksi. Simuloinnit osoittivat kaikkien komponenttien täyttävän tavoitteen polarisaattoria lukuun ottamatta. Sen toimintakaista rajoittui noin 13 prosenttiin 0.5 dB:n akselisuhde- ja 30 dB:n isolaatiovaatimuksen takia. Prototyyppitehonjakajan mitatut ominaisuudet vastasivat varsin hyvin simuloituja: teho jakaantui tasan ja paluuvaimennus oli enemmän kuin 18 dB:ä. Vaikka prototyyppisuodattimen mitattu kaistanleveys oli haluttu, päästökaista oli siirtynyt noin 1 GHz:n verran alemmille taajuuksille. Keskimääräinen väliinkytkemisvaimennus oli 0.8 dB. Jäähdytetyn esivahvistimen keskimääräiseksi kohinalämpötilaksi mitattiin 60 K:iä ja vahvistukseksi 53 dB:ä

Analysis and Measurement of Horn Antennas for CMB Experiments

In this thesis the author's work on the computational modelling and the experimental measurement of millimetre and sub-millimetre wave horn antennas for Cosmic Microwave Background (CMB) experiments is presented. This computational work particularly concerns the analysis of the multimode channels of the High Frequency Instrument (HFI) of the European Space Agency (ESA) Planck satellite using mode matching techniques to model their farfield beam patterns. To undertake this analysis the existing in-house software was upgraded to address issues associated with the stability of the simulations and to introduce additional functionality through the application of Single Value Decomposition in order to recover the true hybrid eigenfields for complex corrugated waveguide and horn structures. The farfield beam patterns of the two highest frequency channels of HFI (857 GHz and 545 GHz) were computed at a large number of spot frequencies across their operational bands in order to extract the broadband beams. The attributes of the multimode nature of these channels are discussed including the number of propagating modes as a function of frequency. A detailed analysis of the possible effects of manufacturing tolerances of the long corrugated triple horn structures on the farfield beam patterns of the 857 GHz horn antennas is described in the context of the higher than expected sidelobe levels detected in some of the 857 GHz channels during flight. Additionally the pre-flight measurements of the flight horns and qualification horn are analysed in detail which verifies the multimode nature of the horns. This computational work is complemented by a novel approach to the measurement of millimetre-wave antennas using digital holographic techniques particularly with the location of their phase centres in mind. The measurement at 100 GHz of a horn antenna specially designed for future CMB polarisation experiments is presented. Finally some additional applications of millimetre-wave holography are discussed

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Satellite Communications

This study is motivated by the need to give the reader a broad view of the developments, key concepts, and technologies related to information society evolution, with a focus on the wireless communications and geoinformation technologies and their role in the environment. Giving perspective, it aims at assisting people active in the industry, the public sector, and Earth science fields as well, by providing a base for their continued work and thinking