High‐performance microstrip directional coupler for radio‐astronomical receivers at cryogenic temperature

Valente, G.; Montisci, Giorgio; Mariotti, Sergio

doi:10.1049/el.2014.0078

Cited by 20 publications

(18 citation statements)

References 3 publications

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“…This cable adds a further noise contribution of order 1-1.5 K to the receiver chain [19]. On the other hand, in our case, the OMT, the directional coupler (see [3]), and the LNA are all refrigerated at the same cryogenic temperature of 20 K, thus no cable providing thermal isolation is required between the directional coupler and the LNA. As a consequence, lowering the operating temperature of both the OMT and the directional coupler to 20 K not only reduces individually the noise temperature added by these two components, but also further reduces the whole system noise temperature compared to the receiver of [19] because no cable for thermal isolation is required.…”

Section: Introductionmentioning

confidence: 92%

“…In order to reduce the system noise temperature of the L-band receiver chain, some of the key components [OMT, directional couplers [3], and low-noise amplifiers (LNAs)] are thermalized at cryogenic temperatures and housed inside a compact cryostat. The cryogenic system consists of a two-stage cryo-cooler with nominal temperatures of 20 and 77 K. The design of the cryostat is constrained by the limited space available in the direction of the optical axis inside the focal cabin of the radio telescope, thus requiring a very compact design of all components of the receiver chain, including the OMT.…”

Section: Introductionmentioning

confidence: 99%

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A Compact L-Band Orthomode Transducer for Radio Astronomical Receivers at Cryogenic Temperature

Valente

Montisci

Pisanu

et al. 2015

IEEE Trans. Microwave Theory Techn.

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We describe the design, construction and\ud performance of a compact orthomode transducer (OMT) for the\ud L-band receiver (1.3 GHz - 1.8 GHz) of the Sardinia Radio\ud Telescope (SRT). The complete OMT consists of a cylindrical\ud orthomode junction (OMJ), which is presented in this paper, and\ud two identical 180° hybrid power combiners in double ridged\ud waveguide, which have been proposed in a previous work. The\ud OMT operates at the cryogenic temperature of 20 K to reduce its\ud thermal noise contribution to the noise of the receiving chain.\ud Therefore, particular care has been taken in the design of the\ud OMJ to minimize its dimension and insure a good thermalization.\ud The proposed OMT has been designed and optimized by using\ud CST Microwave studio, and then manufactured, tested at room\ud temperature, and installed on the L-band receiver of SRT. The\ud measured results fully comply with the design specifications. In\ud particular, the isolation between the OMT output ports is more\ud than 40 dB, and the cross polarization is less than -35 dB for both\ud polarization channels

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

A Compact L-Band Orthomode Transducer for Radio Astronomical Receivers at Cryogenic Temperature

Valente

Montisci

Pisanu

et al. 2015

IEEE Trans. Microwave Theory Techn.

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“…In full operational mode, the SRT is able to host up to 20 remotely controllable receivers and to observe the sky with high efficiency in the frequency range between 0.3-116 GHz [13]. In order to observe the signal sent from FTS and scattered by the debris, the coaxial dual-feed L-P band (0.305-0.410 GHz, 1.3-1.8 GHz) cryogenic receiver of SRT has been used ( Figure 1) [14][15][16][17]. The features of the transmitter and receiver antennas at 410 MHz are reported in Table 1.…”

Section: Bistatic Radar For Leo Trackingmentioning

confidence: 99%

Space Debris Detection in Low Earth Orbit with the Sardinia Radio Telescope

et al. 2017

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Space debris are orbiting objects that represent a major threat for space operations. The most used countermeasure to face this threat is, by far, collision avoidance, namely the set of maneuvers that allow to avoid a collision with the space debris. Since collision avoidance is tightly related to the knowledge of the debris state (position and speed), the observation of the orbital debris is the key of the problem. In this work a bistatic radar configuration named BIRALET (BIstatic RAdar for LEO Tracking) is used to detect a set of space debris at 410 MHz, using the Sardinia Radio Telescope as the receiver antenna. The signal-to-noise ratio, the Doppler shift and the frequency spectrum for each debris are reported.

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“…The most popular configuration of a directional coupler is the standard coupled-line directional coupler (SC) [2][3][4], which allows the realization of quite a compact coupler with good bandwidth. Moreover, the coupled port is DC isolated from the through line.…”

Section: Introductionmentioning

confidence: 99%

Design of a Low-Cost Microstrip Directional Coupler with High Coupling for a Motion Detection Sensor

Sanna

Montisci

Jin³

et al. 2018

Electronics

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Abstract:A coupled-line coupler based on the asymmetric cascade connection of two coupled line sections is used to achieve a high coupling factor using low-cost material and technology in the X frequency band, and its performance is compared with a standard quarter-wave, coupled-line coupler, showing an increase in the coupling factor of about 3 dB. The proposed coupler can be effectively used in a Doppler motion detection sensor, due to its strong coupling and relatively high isolation. The coupler is designed through a simple, yet rigorous, equivalent circuital model. Then, an optimization procedure was performed using the commercial software Ansys HFSS in order to compensate for losses and second order effects. A prototype of the designed coupler was realized, and the measured data show very good agreement with simulations.

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High‐performance microstrip directional coupler for radio‐astronomical receivers at cryogenic temperature

Cited by 20 publications

References 3 publications

A Compact L-Band Orthomode Transducer for Radio Astronomical Receivers at Cryogenic Temperature

A Compact L-Band Orthomode Transducer for Radio Astronomical Receivers at Cryogenic Temperature

Space Debris Detection in Low Earth Orbit with the Sardinia Radio Telescope

Design of a Low-Cost Microstrip Directional Coupler with High Coupling for a Motion Detection Sensor

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