Dual-polarization Receiver Research Articles

A high-performance compact WR-4 orthomode transducer for wideband communications

Abstract This paper presents the design, fabrication and performance evaluation of a compact orthomode transducer (OMT) optimized for wideband communications. The OMT developed in this work features a circular waveguide as its common port, ensuring direct compatibility with receivers such as horn antennas, meanwhile enabling dual-polarization capabilities. The operational frequency spectrum of the OMT spans the entire WR-4 band (170 GHz-260 GHz), achieving reflection coefficients surpassing 20 dB and port isolation better than 60 dB, as validated through electromagnetic (EM) simulations. To evaluate performance of the fabricated OMT in a practical dual-polarization system, the OMT is utilized as the feed source for a horn antenna to realize a dual-polarized horn antenna system. The results demonstrate that the antenna incorporating the OMT exhibits superior performance, with average reflection coefficients better than 20 dB and port isolation exceeding 40 dB for overall operational band. These results indicate that the OMT developed in this work successfully meets the demanding requirements for polarization multiplexing in wideband dual-polarized receiver systems.

Advances in Adaptive Filtering for Coherent Dual-Polarization Optical Communication Systems and Their Integration in Dynamic Optical Networks

A thorough examination of current developments in adaptive filtering for coherent dualpolarization optical communication systems is provided in this work. The emphasis is on high-capacity networks made possible by dual-polarization, coherent detection, variable bit-rate transceivers. The review explores the effectiveness of different adaptive algorithms in coherent receivers, the importance of dual polarization, and the function of adaptive filters in reducing channel impairments. The research also sheds light on the tradeoffs and difficulties related to flexible bitrate optical transceivers. The paper comprises an extensive assessment of dynamic optical networks, categorized by network granularity and generation, in addition to the study of adaptive filtering. A comprehensive understanding of the developments in dynamic optical networking technologies is provided by the discussion of the evolution and traits of each generation. The poll also covers optical access networks, emphasizing the acceptance and advantages of optical access protocols as IEEE EPON and ITU-T GPON. The study also examines how digital filtering might be used to manage transmission constraints, highlighting the significance of segmenting digital filtering into distinct blocks. An overview of the types and applications of optical filters utilized in optical communication systems is included in the discussion. The study wraps up with a review of the literature that summarizes current research on optical communication systems, such as studies on adaptive algorithms' convergence properties, coherent dual-polarization receivers, and machine learning's use in optical fiber communication. The contributions of this paper include a thorough analysis of adaptive algorithm performance, a comparative study of dynamic optical networks, and a comprehensive overview of recent research in optical communication systems.

Design of a 240 GHz on-chip dual-polarization receiver for SIS mixer arrays

We report the design of a compact dual-polarization on-chip superconductor–insulator–superconductor receiver for array applications. The planar-circuit receiver chip is comprised of the entire radio frequency (RF) signal processing chain with three main circuit components alongside some auxiliary circuits: (1) a polarization splitting 4-probe orthomode transducer (OMT) that couples the RF and local oscillator signal from free space to the chip via a drilled feedhorn; (2) two hybrids that recombine the power of each polarization from the two sets of orthogonal OMT probes; and (3) twin-junction Nb/AlOx/Nb mixers that downconvert the recombined signals to the intermediate frequency. We ensure that the four side walls of each pixel are free from obscuration, using only the top and bottom of the pixel for various connections. Consequently, the design is extendable to a large format array. In this paper, we present the detailed design of the on-chip receiver, including extensive heterodyne simulations and its potential extension into a large format array.

On Antenna Polarization Axes in L-Band Aperture Synthesis Arrays With Dual Polarization Receivers for Earth Observation

On Antenna Polarization Axes in L-Band Aperture Synthesis Arrays With Dual Polarization Receivers for Earth Observation

A 1024-Element Ku-Band SATCOM Dual-Polarized Receiver With >10-dB/K G/T and Embedded Transmit Rejection Filter

This article presents a 1024-element dual-polarized Ku-band (10.7–12.7 GHz) satellite communication (SATCOM) receive (RX) phased array. The array consists of four 16 $\times16$ subarray tiles, each of which comprises 64 eight-channel beamformer chips, 256 dual-channel low-noise amplifiers (LNAs), and 256 dual-polarized antennas built on an affordable printed circuit board (PCB). The antennas spaced at $\lambda $ /2 spacing at 12.2 GHz in an equilateral triangular grid allow scanning up to x±70° in all planes while maintaining a cross-polarization level $ dB. The use of LNAs just after the antennas enables a low-noise operation with an antenna gain-to-noise temperature (G/T) of 10.5 dB/K ( $T_{\mathrm {ant}} =20$ K) at broadside while maintaining a directivity of 34 dB at 11.7 GHz. Also, a two-pole/two-zero filter is placed between the LNA and the beamformer chip to greatly attenuate any transmit leakage signal at 14–14.5 GHz. The lightweight, low-cost PCB with all silicon chips and a thickness of 3.4 mm presents a viable candidate for Ku-band SATCOM ground and Satcom-On-The-Move (SOTM) terminals.

A 26–32-GHz Dual-Polarization Receiver Front-End With Rapid-Response Mixed-Signal Polarization Alignment for Ultrareliable Low-Latency Communications

A 26–32-GHz Dual-Polarization Receiver Front-End With Rapid-Response Mixed-Signal Polarization Alignment for Ultrareliable Low-Latency Communications

Design, operation and performance of the PAON4 prototype transit interferometer

ABSTRACT PAON4 is an L-band (1250–1500 MHz) small interferometer operating in transit mode deployed at the Nançay observatory in France, designed as a prototype instrument for intensity mapping. It features four 5 m diameter dishes in a compact triangular configuration, with a total geometric collecting area of ${\sim} 75\, \mathrm{m^2}$, and is equipped with dual polarization receivers. A total of 36 visibilities are computed from the eight independent RF signals by the software correlator over the full 250 MHz RF band. The array operates in transit mode, with the dishes pointed toward a fixed declination, while the sky drifts across the instrument. Sky maps for each frequency channel are then reconstructed by combining the time-dependent visibilities from the different baselines observed at different declinations. This paper presents an overview of the PAON4 instrument design and goals, as a prototype for dish arrays to map the large-scale structure in radio, using intensity mapping of the atomic hydrogen 21 cm line. We operated PAON4 over several years and use data from observations at different periods to assess the array performance. We present a preliminary analysis of a large fraction of these data and discuss crucial issues for this type of instrument, such as the calibration strategy, instrument response stability and noise behaviour.

Design and Performance of a Sideband Separating SIS Mixer for 800–950 GHz

We present the design and results of characterization of a new sideband separating (2SB) mixer for 800–950 GHz, based on superconductor–insulator–superconductor (SIS) junctions. This is the first waveguide 2SB SIS mixer demonstrated at such a high frequency. The design is following the classical quadrature hybrid architecture, meanwhile additional attention was put on the reduction of reflections in the RF structure in order to minimize the RF imbalance, to achieve a high image rejection ratio (IRR). The RF waveguide block was manufactured by micromilling and populated by single-ended SIS mixers developed earlier for upgrade of the CHAMP+ high-band array on the APEX telescope. These SIS mixers have double-sideband (DSB) noise temperatures from 210 to 400 K. The assembled 2SB mixer yields a SSB noise temperature from 450 to 900 K, with an IRR above 15 dB in 95% of the band. Comparing the DSB and the SSB sensitivities, we find that the waveguide losses are as low as expected and do not exceed 0.6 dB. The presented mixer is a prototype for use in a 2SB dual polarization receiver planned for deployment on the APEX telescope.

DSA-10: a prototype array for localizing fast radio bursts

ABSTRACT The Deep Synoptic Array 10-dish prototype (DSA-10) is an instrument designed to detect and localize fast radio bursts with arcsecond accuracy in real time. Deployed at Owens Valley Radio Observatory, it consists of ten 4.5-m diameter dishes, equipped with a 250-MHz bandwidth dual polarization receiver, centred at 1.4 GHz. The 20 input signals are digitized and field programmable gate arrays are used to transform the data to the frequency domain and transmit it over ethernet. A series of computer servers buffer both raw data samples and perform a real time search for fast radio bursts on the incoherent sum of all inputs. If a pulse is detected, the raw data surrounding the pulse are written to disc for coherent processing and imaging. The prototype system was operational from 2017 June to 2018 February conducting a drift scan search. Giant pulses from the Crab Pulsar were used to test the detection and imaging pipelines. The 10-dish prototype system was brought online again in 2019 March, and will gradually be replaced with the new DSA-110, a 110-dish system, over the next 2 yr to improve sensitivity and localization accuracy.

1.25–1.57 THz Dual-Polarization Receiver Optics Based on Corrugated Horns

High-performance dual-polarization receiver optics is a key component of terahertz applications with stringent requirements, such as radio astronomy or planetary exploration. Usually, such optics use corrugated horns due to their excellent wideband performance. However, this kind of horns is difficult to fabricate for frequencies higher than 1 THz. Traditionally, the performance of optics at frequencies over 1 THz is thus limited by the choice of feed horn, usually a diagonal or smooth-wall horn. This choice limits the effective maximum aperture efficiency or bandwidth achievable, respectively. Recently, we successfully fabricated direct-machined terahertz corrugated horns with good beam characteristics and low cross polarization. Based on these horns, we have designed full receiver optics for a possible future ALMA band 11 (1.25–1.57 THz) receiver. The polarization separation is achieved by means of a wire grid. A prototype has been fabricated and tested on a near-field beam scanner. It shows aperture efficiency above 85% and polarization efficiency above 99.6% at all measured frequencies. This complies with the stringent requirements of the ALMA telescope for frequencies between 35 and 950 GHz. To our knowledge, these are the highest aperture and polarization efficiencies achieved over such a wide bandwidth at around 1.4 THz.

SEPIA – a new single pixel receiver at the APEX telescope

Context. We describe the new Swedish-ESO PI Instrument for APEX (SEPIA) receiver, which was designed and built by the Group for Advanced Receiver Development (GARD), at Onsala Space Observatory (OSO) in collaboration with ESO. It was installed and commissioned at the APEX telescope during 2015 with an ALMA Band 5 receiver channel and updated with a new frequency channel (ALMA Band 9) in February 2016. Aim. This manuscript aims to provide, for observers who use the SEPIA receiver, a reference in terms of the hardware description, optics and performance as well as the commissioning results. Methods. Out of three available receiver cartridge positions in SEPIA, the two current frequency channels, corresponding to ALMA Band 5, the RF band 158–211 GHz, and Band 9, the RF band 600–722 GHz, provide state-of-the-art dual polarization receivers. The Band 5 frequency channel uses 2SB SIS mixers with an average SSB noise temperature around 45 K with IF (intermediate frequency) band 4–8 GHz for each sideband providing total 4 × 4 GHz IF band. The Band 9 frequency channel uses DSB SIS mixers with a noise temperature of 75–125 K with IF band 4–12 GHz for each polarization. Results. Both current SEPIA receiver channels are available to all APEX observers.

Impact of Perturbations on Nonlinear Frequency-Division Multiplexing

Nonlinear frequency-division multiplexing (NFDM) is a communication scheme in which users’ signals are multiplexed in the nonlinear Fourier domain. The contributions of this paper are twofold. First, the achievable information rates (AIRs) of NFDM based on an integrable model of the optical fiber are summarized. For this ideal model, it is shown that the AIR of the NFDM is greater than the AIR of the wavelength-division multiplexing (WDM) for a given bandwidth and signal power, in a representative system with five users and one symbol per user. The improvement results from nonlinear signal multiplexing. Second, the impact of some of the main perturbations on NFDM are investigated, including the fiber loss, polarization effects, and the third-order dispersion. For a realistic nonideal model, it is shown that the WDM AIR with joint dual-polarization back-propagation and third-order dispersion compensation is approximately equal to the NFDM AIR with two independent single-polarization demodulations and without third-order dispersion compensation. Using a joint dual-polarization receiver and perturbations compensation is expected to increase the NFDM AIR.

Dual-Polarization Observations of Slowly Varying Solar Emissions from a Mobile X-Band Radar.

The radio noise that comes from the Sun has been reported in literature as a reference signal to check the quality of dual-polarization weather radar receivers for the S-band and C-band. In most cases, the focus was on relative calibration: horizontal and vertical polarizations were evaluated versus the reference signal mainly in terms of standard deviation of the difference. This means that the investigated radar receivers were able to reproduce the slowly varying component of the microwave signal emitted by the Sun. A novel method, aimed at the absolute calibration of dual-polarization receivers, has recently been presented and applied for the C-band. This method requires the antenna beam axis to be pointed towards the center of the Sun for less than a minute. Standard deviations of the difference as low as 0.1 dB have been found for the Swiss radars. As far as the absolute calibration is concerned, the average differences were of the order of −0.6 dB (after noise subtraction). The method has been implemented on a mobile, X-band radar, and this paper presents the successful results that were obtained during the 2016 field campaign in Payerne (Switzerland). Despite a relatively poor Sun-to-Noise ratio, the “small” (~0.4 dB) amplitude of the slowly varying emission was captured and reproduced; the standard deviation of the difference between the radar and the reference was ~0.2 dB. The absolute calibration of the vertical and horizontal receivers was satisfactory. After the noise subtraction and atmospheric correction a, the mean difference was close to 0 dB.

Calibration Accuracy of the Dual-Polarization Receivers of the C-Band Swiss Weather Radar Network

The electromagnetic power that comes from the Sun has been proved to be an effective reference for checking the quality of dual-polarization weather radar receiver. Operational monitoring methods have been developed and implemented for determining the electromagnetic antenna pointing, assessing the receiver stability, and the differential reflectivity offset. So far, the focus has been on relative calibration: horizontal and vertical polarization have been mutually compared and evaluated versus the reference mainly in terms of standard deviation of the error. Radar receivers have been able to capture and describe the monthly variability (slowly varying component) of the microwave signal emitted by the Sun. In this paper, we present results from a novel Sun-based method aiming at the absolute calibration of dual-polarization weather radar receivers. To obtain best results, the radar receiver has to be off-line for a few minutes during the tracking of the Sun in order to have the antenna beam axis pointing at the center of the Sun. Among the five polarimetric weather radar receivers of the Swiss network, radar “WEI” located at an altitude of 2850 m next to Davos shows the best absolute agreement with the Dominion Radio Astrophysical Observatory (DRAO) reference for both horizontal (H) and vertical (V) polarization. Albis radar, which is located at an altitude of 938 m near Zurich, shows the largest difference: the radar receiver is too low compared to the Sun reference by −1.62 (−1.25) dB for the H (V) channel. Interestingly, the standard deviation of the error is smaller than ±0.17 dB for all Swiss radar receivers. With a standard deviation of ±0.04 dB Albis radar shows the best relative agreement between H and V. These results are encouraging and MeteoSwiss is planning to repeat off-line Sun-tracking measurements in the future on a regular basis.

Field-scale remote sensing of soil moisture based on polarimetric characterization of microwave reflections

A field-scale remote soil moisture sensing technique that exploits polarization mode dispersion (PMD) associated with radio frequency (RF) signal propagation is considered in this paper. Microwave polarization responses from rough surface scattering are quantified using a dual-polarized receiver system to estimate PMD responses. Changes in PMD response are elicited by changes in the dielectric properties due to soil moisture changes. The ability of PMD characterizations to remotely detect changes in soil moisture, with responses that exhibit good correlation to ground probe measurements, is demonstrated using a prototype with widely separated transmitter/receiver system deployed at the MATERHORN field experiments conducted at the US Army Dugway Proving Ground, Utah.

A new 3 mm band receiver for the Onsala 20 m antenna

A new receiver for the Onsala 20 m antenna with the possibility of being equipped with 3 mm and 4 mm bands has been built and the 3 mm channel has been commissioned during the Spring 2014. For single-dish operation, the receiver uses an innovative on-source/off-source optical switch. In combination with additional optical components and within the same optical layout, the switch provides two calibration loads (for the 3 mm and 4 mm channels), sideband rejection measurement, and tuning possibilities. The optical layout of the receiver employs all cold (4 K) offset elliptical mirrors for both channels, whereas the on-off switch employs flat mirrors only. The 3 mm channel employs a sideband separation (2SB) dual polarization receiver with orthomode transducer (OMT), 4-8 GHz intermediate frequency (IF), x? 2pol x? upper and lower sidebands (USB? +? LSB). The cryostat has four optical windows made of high density polyethylene (HDPE) with anti-reflection corrugations, two for the signal and two for each frequency band cold load. The cryostat uses a two-stage cryocooler produced by Sumitomo HI? RDK? 408D2 with anti-vibration suspension of the cold-head to minimize impact of the vibrations on the receiver stability. The local oscillator (LO) system is based on a Gunn oscillator with aphase lock loop (PLL) and four mechanical tuners for broadband operation, providing independently tunable LO power for each polarization. This paper provides a technical description of the receiver and its technology and could be useful for instrumentation engineers and observers using the Onsala 20 m telescope.

The 1.3mm Full-Stokes Polarization System at CARMA

The CARMA 1.3[Formula: see text]mm polarization system consists of dual-polarization receivers that are sensitive to right- (R) and left-circular (L) polarization, and a spectral-line correlator that measures all four cross polarizations ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]) on each of the 105 baselines connecting the 15 telescopes. Each receiver comprises a single feed horn, a waveguide circular polarizer, an orthomode transducer (OMT), two heterodyne mixers, and two low-noise amplifiers (LNAs), all mounted in a cryogenically cooled dewar. Here we review the basics of polarization observations, describe the construction and performance of key receiver components (circular polarizer, OMT, and mixers — but not the correlator), and discuss in detail the calibration of the system, particularly the calibration of the R–L phase offsets and the polarization leakage corrections. The absolute accuracy of polarization position angle measurements was checked by mapping the radial polarization pattern across the disk of Mars. Transferring the Mars calibration to the well-known polarization calibrator 3C286, we find a polarization position angle of [Formula: see text] for 3C286 at 225[Formula: see text]GHz, consistent with other observations at millimeter wavelengths. Finally, we consider what limitations in accuracy are expected due to the signal-to-noise ratio, dynamic range, and primary beam polarization.

Polarization-beam-splitter-less integrated dual-polarization coherent receiver.

Conventional dual-polarization coherent receivers require polarization beam splitters for either the signal or the local oscillator path. This severely hinders monolithic integration, since integrated polarization splitting devices often exhibit stringent fabrication tolerances. Here we propose a dual-polarization monolithically integrated coherent receiver architecture that completely avoids the use of polarization splitting elements. Polarization management is instead achieved by adequately engineering the birefringence of the interconnecting waveguides. The resultant receiver is highly tolerant to fabrication deviations and thus offers a completely new route for monolithic integration of dual-polarization receivers without any type of active tuning.

Development of ALMA Band 4 (125–163 GHz) receiver

Abstract We have developed a dual-polarization receiver for Band 4 of the Atacama Large Millimeter/submillimeter Array (ALMA). Band 4, which covers the 125 to 163 GHz spectral window, is one of the ten bands that form the ALMA Front End. The Band 4 receiver consists of three elements: a warm optics, a cold cartridge assembly, and a warm cartridge assembly. The cold cartridge includes a feed horn, an orthomode transducer, sideband-separating (2SB) superconductor–insulator–superconductor mixers, cold intermediate frequency (IF) amplifiers, IF isolators, bias-protection circuit boards, and component interconnections. The IF bandwidth is 4–8 GHz. The first eight receivers manufactured as preproduction models have demonstrated excellent performance within the stringent ALMA requirements. Stable astronomical fringes and closure phase have been successfully achieved during field performance tests of the Band 4 receivers installed in the ALMA antennas. Our well-established Band 4 receivers will contribute to various fields of astronomical research, such as the detection of high-redshift galaxies, characterization of cold molecular medium in normal field galaxies, and astrochemistry including observations of deuterated species.

Development of the ALMA Band-3 and Band-6 Sideband-Separating SIS Mixers

As the Atacama Large Millimeter/submillimeter Array (ALMA) nears completion, 73 dual-polarization receivers have been delivered for each of Bands 3 (84-116 GHz) and 6 (211-275 GHz). The receivers use sideband-separating superconducting Nb/Al-AlOx/Nb tunnel-junction (SIS) mixers, developed for ALMA to suppress atmospheric noise in the image band. The mixers were designed taking into account dynamic range, input return loss, and signal-to-image conversion (which can be significant in SIS mixers). Typical SSB receiver noise temperatures in Bands 3 and 6 are 30 and 60 K, respectively, and the image rejection is typically 15 dB.