A Novel Compact Low Loss Waveguide Image Rejection Filter Based on a Backward Coupler with Band Pass Filters for 100 GHz Band

Asayama, Shin’ichiro; Mizuno, Akira; Ogawa, Hideo; Onishi, Toshikazu

doi:10.1007/s10762-015-0148-6

Cited by 11 publications

(7 citation statements)

References 17 publications

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“…The hybrid-coupled multiplexer can be made by cascade connections of diplexers (Asayama et al 2015, Hasegawa et al 2017) that consist of branch-line coupler (BLC) and band-pass filter (BPF). These multiplexers were designed to separate a fractional bandwidth of about 30 % (between minimum frequency and maximum frequency) in the RF band into 3 or 4 bands (Kojima et al 2017, Nakajima et al 2020 to achieve the simultaneous observations of molecular lines.…”

Section: Introduction To the Waveguide Multiplexer Systemmentioning

confidence: 99%

Development of a new wideband heterodyne receiver system for the Osaka 1.85-m mm-submm telescope -- Receiver development & the first light of simultaneous observation in 230GHz and 345GHz bands with an SIS-mixer with 4-21GHz IF output

Masui,

Yamasaki,

Ogawa

et al. 2021

Preprint

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We have developed a wideband receiver system for simultaneous observations in CO lines of J = 2-1 and J = 3-2 transitions using the Osaka 1.85-m mm-submm telescope. As a frequency separation system, we developed multiplexers that connect three types of diplexers, each consisting of branch-line couplers and high-pass filters. The radio frequency (RF) signal is eventually distributed into four frequency bands, each of which is fed to a superconductorinsulator-superconductor (SIS) mixer. The RF signal from the horn is divided into two frequency bands by a wideband diplexer with a fractional bandwidth of 56 %, and then each frequency band is further divided into two bands by each diplexer. The developed multiplexers 1 were designed, fabricated, and characterized using a vector network analyzer. The measurement results showed good agreement with the simulation. The receiver noise temperature was measured by connecting the SIS-mixers, one of which has a wideband 4-21 GHz intermediate frequency (IF) output. The receiver noise temperatures were measured to be ∼70 K in the 220 GHz band, ∼100 K in the 230 GHz band, 110-175 K in the 330 GHz band, and 150-250 K in the 345 GHz band. This receiver system has been installed on the 1.85-m telescope at the Nobeyama Radio Observatory. We succeeded in the simultaneous observations of six CO isotopologue lines with the transitions of J = 2-1 and J = 3-2 toward the Orion KL as well as the on-the-fly (OTF) mappings toward the Orion KL and W 51.

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Section: Introduction To the Waveguide Multiplexer Systemmentioning

confidence: 99%

Development of a new wideband heterodyne receiver system for the Osaka 1.85-m mm-submm telescope -- Receiver development & the first light of simultaneous observation in 230GHz and 345GHz bands with an SIS-mixer with 4-21GHz IF output

Masui,

Yamasaki,

Ogawa

et al. 2021

Preprint

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“…Furthermore, this structure is less producing a standing wave between the input and reflected signal due to its directional property of the out-of-band reflection and in-band transmission of the BPFs. This mechanism was described by Asayama et al (2015) [23] and Hasegawa et al (2017) [27]. In particular, the applicability of the wave-guide type hybrid-coupled multiplexer at the sub-millimeter band was demonstrated by Kojima et al (2017).…”

Section: Receiver Configurationsmentioning

confidence: 99%

“…A multiorder BPF with symmetric walls was designed, which is referred to as an iriscoupled filter (e.g., [28]). The scaled sizes of the IRF by Asayama et al (2015) were set as the initial input of a parametric model optimization analysis using HFSS software. The resultant dimensions of the waveguide are shown in Figure 4, and specific values are listed in Table 2.…”

Section: Waveguide Component Designmentioning

confidence: 99%

“…[8]). In this case, an image rejection filter (IRF), which consists of a branch-line quadrature hybrid coupler and two band pass filters (BPFs) based on the waveguide technique [23], was implemented in the spectroradiometers in the 100 GHz band at Hokkaido, Japan and Río Gallegos, Argentina. As a result, Ohyama et al (2016) confirmed the stable operation and reliability of this IRF for long-term monitoring of the ozone variation in the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

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Waveguide-Type Multiplexer for Multiline Observation of Atmospheric Molecules using Millimeter-Wave Spectroradiometer

Nakajima,

Haratani,

Mizuno

et al. 2020

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In order to better understand the variation mechanism of ozone abundance in the middle atmosphere, the simultaneous monitoring of ozone and other minor molecular species, which are related to ozone depletion, is the most fundamental and critical method. A waveguide-type multiplexer was developed for the expansion of the observation frequency range of a millimeter-wave spectroradiometer, for the simultaneous observation of multiple molecular spectral lines. The proposed multiplexer contains a cascaded four-stage sideband-separating filter circuit. The waveguide circuit was designed based on electromagnetic analysis, and the pass frequency bands of Stages 1-4 were [243][244][245][246][247][248][249][250][251][227][228][229][230][231][232][233][234][235][197][198][199][200][201][202][203][204][205][181][182][183][184][185][186][187][188][189] GHz. The insertion and return losses of the multiplexer were measured using vector network analyzers, each observation band was well-defined, and the bandwidths were appropriately specified. Moreover, the receiver noise temperature and the image rejection ratio (IRR) using the superconducting mixer at 4 K were measured. As a result, the increase in receiver noise due to the multiplexer compared with that of only the mixer can be attributed to the transmission loss of the waveguide circuit in the multiplexer. The IRRs were higher than 25 dB at the center of each observation band. This indicates that a high and stable IRR performance can be achieved by the waveguide-type multiplexer for the separation of sideband signals.

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“…This system converts the input signal emitted by the atmospheric ozone molecules in their rotational transitions (~ 110,836 GHz) into the lower intermediate frequency (IF~6 GHz). The mixer operates in single side band (SSB) using a wave guide to filter the image band (Asayama et al, 2015) and it is cooled at 4K to reach the superconductive state. This operational temperature improves the signal to noise ratio to obtain a high temporal resolution (~1 hour).…”

Section: Millimeter Wave Radiometermentioning

confidence: 99%

Analysis of an event of short term ozone variation using a Millimiter-Wave Radiometer installed in subpolar region

Orte

Wolfram

Salvador

et al. 2019

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Abstract. Subpolar regions in the southern hemisphere are influenced by the Antarctic polar vortex during austral spring, which induces high and short term ozone variability at different altitudes mainly into the stratosphere. This variation may affect considerably the total ozone column changing the harmful UV radiation that reaches the surface. With the aim to study ozone with high time resolution at different altitudes in subpolar regions, a Millimeter Wave Radiometer (MWR) was installed at the Observatorio Atmosférico de la Patagonia Austral (OAPA), Río Gallegos, Argentina, (51.6° S; 69.3° W) by 2011. This instrument provides ozone profiles with time resolution of ~ 1 hour which enables studies of short term ozone mixing ratio variability from 25 to 70 km in altitude. This work presents the MWR ozone observations between October 2014 and 2015 focusing on an atypical event of polar vortex and ozone hole influence over Río Gallegos detected from the MWR measurements at 27 and 37 km during November of 2014. The advected potential vorticity (APV) calculated from the high-resolution advection model MIMOSA (Modélisation Isentrope du transport Méso-échelle de l'Ozone Stratosphérique par Advection) was also analysed at 675 and 950 K to understand and explain the dynamic at both altitudes and correlate the ozone rapid variation during the event with the passage of the polar vortex. In addition, the MWR dataset were compared for first time with measurements obtained from Microwave Limb Sounder (MLS) at individual altitude levels (27 km, 37 km and 65 km) and with the Differential Absorption Lidar (DIAL) installed in OAPA to analyse the correspondence between the MWR and independent instruments. The MWR-MLS comparison presents reasonable correlation with a mean bias error of +5 %, −11 % and −7 % at 27 km, 37 km and 65 km, respectively. The MWR-DIAL comparison at 27 km presents also good agreement with a mean bias error of −1 %.

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A Novel Compact Low Loss Waveguide Image Rejection Filter Based on a Backward Coupler with Band Pass Filters for 100 GHz Band

Cited by 11 publications

References 17 publications

Development of a new wideband heterodyne receiver system for the Osaka 1.85-m mm-submm telescope -- Receiver development & the first light of simultaneous observation in 230GHz and 345GHz bands with an SIS-mixer with 4-21GHz IF output

Development of a new wideband heterodyne receiver system for the Osaka 1.85-m mm-submm telescope -- Receiver development & the first light of simultaneous observation in 230GHz and 345GHz bands with an SIS-mixer with 4-21GHz IF output

Waveguide-Type Multiplexer for Multiline Observation of Atmospheric Molecules using Millimeter-Wave Spectroradiometer

Analysis of an event of short term ozone variation using a Millimiter-Wave Radiometer installed in subpolar region

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