An X-band low noise amplifier (LNA) using the 70 nm GaAs metamorphic high electron mobility transistors (mHEMT) process available from OMMIC has been reported. The foundry model-based simulated response, on-wafer measurements of the fabricated monolithic microwave integrated circuit (MMIC) LNA and measured data of packaged LNA at room temperature and 100 K have been shown. At room temperature, the packaged LNA exhibits a flat gain more than 26 dB from 7 to 11 GHz with less than 1 dB noise figure at room temperature. The input and output return losses are better than -20 and -10 dB, respectively, between 7.5 and 8.5 GHz. It exhibits linear response with output 1 dB compression point of 1 dBm. MMIC dimension has been limited to 1.5 mm x 1 mm. Off-chip inductance in the form of a modelled bondwire has been used to attain the improved input return loss and noise matching. Two figure-of-merits have been proposed and justified, and a comparative study of the overall performances of X-band LNAs with emerging technologies has been made. At 100 K, the LNA shows major improvement of the input and output return losses.

We present the calibration and scientific performance parameters of the Planck Low Frequency Instrument (LFI) measured during the ground cryogenic test campaign. These parameters characterise the instrument response and constitute our optimal pre-launch knowledge of the LFI scientific performance. The LFI shows excellent 1/f stability and rejection of instrumental systematic effects; its measured noise performance shows that LFI is the most sensitive instrument of its kind. The calibration parameters will be updated during flight operations until the end of the mission.

A bandpass filter using symmetrical Left-Handed (LH) transmission line (TL) Zeroth-Order Resonators (ZOR) is proposed. The symmetrical LH TL is first characterized by the dispersion characteristics of the unit cell and its left handedness is verified by the transmission characteristics of 15 cells cascaded LH TL. A symmetrical LH TL open circuited on both sides, acting as a ZOR with shunt resonance, is used as a resonating element in the microstrip end coupled resonator bandpass filter. The open circuited ZOR is characterized by susceptance slope parameter, and bandpass filter is designed using microstrip series gaps as the admittance inverters. Size independent resonance property of the ZOR combined with homogeneity condition of the LH TL unit cell is utilized in the size reduction of bandpass filter. The full wave simulated transmission characteristics of the designed bandpass filter are experimentally verified. They show that size of the filter is greatly reduced (approximately 64%) when compared to a conventional half wavelength coupled bandpass filter.

The Low Frequency Instrument (LFI) on-board the ESA Planck satellite carries eleven radiometer subsystems, called radiometer chain assemblies (RCAs), each composed of a pair of pseudo-correlation receivers. We describe the on-ground calibration campaign performed to qualify the flight model RCAs and to measure their pre-launch performances. Each RCA was calibrated in a dedicated flight-like cryogenic environment with the radiometer front-end cooled to 20 K and the back-end at 300 K, and with an external input load cooled to 4 K. A matched load simulating a blackbody at different temperatures was placed in front of the sky horn to derive basic radiometer properties such as noise temperature, gain, and noise performance, e. g. 1/f noise. The spectral response of each detector was measured as was their susceptibility to thermal variation. All eleven LFI RCAs were calibrated. Instrumental parameters measured in these tests, such as noise temperature, bandwidth, radiometer isolation, and linearity, provide essential inputs to the Planck-LFI data analysis.

In this paper we present the Low Frequency Instrument (LFI), designed and developed as part of the Planck space mission, the ESA program dedicated to precision imaging of the cosmic microwave background (CMB). Planck-LFI will observe the full sky in intensity and polarisation in three frequency bands centred at 30, 44 and 70 GHz, while higher frequencies (100-850 GHz) will be covered by the HFI instrument. The LFI is an array of microwave radiometers based on state-of-the-art Indium Phosphide cryogenic HEMT amplifiers implemented in a differential system using blackbody loads as reference signals. The front-end is cooled to 20K for optimal sensitivity and the reference loads are cooled to 4K to minimise low frequency noise. We provide an overview of the LFI, discuss the leading scientific requirements and describe the design solutions adopted for the various hardware subsystems. The main drivers of the radiometric, optical and thermal design are discussed, including the stringent requirements on sensitivity, stability, and rejection of systematic effects. Further details on the key instrument units and the results of ground calibration are provided in a set of companion papers.

The Planck Low Frequency Instrument (LFI) radiometers have been tested extensively during several dedicated campaigns. The present paper reports the principal noise properties of the LFI radiometers. A brief description of the LFI radiometers is given along with details of the test campaigns relevant to determination of noise properties. Current estimates of flight sensitivities, 1/f parameters, and noise effective bandwidths are presented. The LFI receivers exhibit exceptional 1/f noise, and their white noise performance is sufficient for the science goals of Planck.

This paper summarizes the approach of the implementation of a differential input and single-ended output low noise amplifier for the square kilometer array development system. A new procedure to test such LNAs has also been proposed here. As a part of the initial approach for this design idea two MIC LNAs have been designed to be tested in the proposed method. Avago Technology's ATF33143 pHEMT transistors have used to develop the designs. LNA1 has a flat gain of more than 30 dB with noise figure of around 0.6 dB. The return losses are also good over the band. The LNA2 displays gain over 28 dB and noise figure less than 0.7 dB almost all across the band. The true differential mixed mode S-parameter response of both the LNAs has been presented here. With success these design and testing procedures would be implemented on future MMIC LNAs to be developed for the SKA.

A novel via-free microstrip Left Handed (LH) Transmission Line (TL) utilizing Radial Stubs (RS) is proposed. The microstrip RS is approximated by a series combination of inductance and capacitance. The electrical equivalent circuit of LH TL unit cell including the equivalent inductance and capacitance of radial stub is discussed. The balanced and unbalanced LH TL is implemented in microstrip technology and backward waves are confirmed by both full wave simulations and experiments. Additionally an open-circuited Zeroth Order Resonators (ZOR) with their resonating properties in balanced and unbalanced left handed transmission lines are also verified by full wave simulations and experiments.

This paper describes the impact of the Planck Low Frequency Instrument front end physical temperature fluctuations on the output signal. The origin of thermal instabilities in the instrument are discussed, and an analytical model of their propagation and impact on the receivers signal is described. The experimental test setup dedicated to evaluate these effects during the instrument ground calibration is reported together with data analysis methods. Finally, main results obtained are discussed and compared to the requirements.

The Low Frequency Instrument on board the PLANCK satellite is designed to give the most accurate map ever of the CMB anisotropy of the whole sky over a broad frequency band spanning 27 to 77 GHz. It is made of an array of 22 pseudo-correlation radiometers, composed of 11 actively cooled (20 K) Front End Modules (FEMs), and 11 Back End Modules (BEMs) at 300K, each FEM and BEM set comprising two radiometers. The connection between the two parts is made with rectangular Wave Guides (WGs). Considerations of very different nature (thermal, electromagnetic and mechanical), imposed stringent requirements on the WGs characteristics and drove their design. From the thermal point of view, the WG should guarantee good insulation between the FEM and the BEM sections to avoid overloading the cryocooler. On the other hand it is essential that the signals do not undergo excessive attenuation through the WG. Finally, given the different positions of the FEM modules behind the focal surface and the mechanical constraints given by the surrounding structures, different mechanical designs were necessary. A composite configuration of Stainless Steel and Copper was selected to satisfy all the requirements described. Given the complex shape and the considerable length (about 1.5-2 m) of the LFI WGs, manufacturing and testing the WGs was a challenge. 1Corresponding author. 2Present address: R&D Technology Development, Numoyx Italy s.r.l., via C. Olivetti 2, 20041 Agrate Brianza (Mi),

The Low Frequency Instrument (LFI) is a radiometer array covering the 30-70 GHz spectral range on-board the ESA Planck satellite, launched on May 14th, 2009 to observe the cosmic microwave background (CMB) with unprecedented precision.In this paper we describe the development and validation of a software model of the LFI pseudo-correlation receivers which enables to reproduce and predict all the main system parameters of interest as measured at each of the 44 LFI detectors. These include system total gain, noise temperature, band-pass response, non-linear response. The LFI Advanced RF Model (LARFM) has been constructed by using commercial software tools and data of each radiometer component as measured at single unit level.The LARFM has been successfully used to reproduce the LFI behavior observed during the LFI ground-test campaign. The model is an essential element in the database of LFI data processing center and will be available for any detailed study of radiometer behaviour during the survey.

A hybrid EBG structure is realized by etching rectangular slots and circular patterns in the ground plane of the microstrip line. A method is proposed by which the ripples in the passband of the rectangular slots are minimized, without degradation of the stopband rejection, by introducing a circular pattern between the rectangular slots. This novel hybrid EBG structure has been designed, fabricated and measured in order to verify the present approach. The simulated and measured results of this hybrid EBG structure have good agreement.

In this paper we discuss the linearity response of the Planck-LFI receivers, with particular reference to signal compression measured on the 30 and 44 GHz channels. In the article we discuss the various sources of compression and present a model that accurately describes data measured during tests performed with individual radiomeric chains. After discussing test results we present the best parameter set representing the receiver response and discuss the impact of non linearity on in-flight calibration, which is shown to be negligible.

We give a description of the design, construction and testing of the 30 and 44 GHz Front End Modules (FEMs) for the Low Frequency Instrument (LFI) of the Planck mission to be launched in 2009. The scientific requirements of the mission determine the performance parameters to be met by the FEMs, including their linear polarization characteristics. The FEM design is that of a differential pseudo-correlation radiometer in which the signal from the sky is compared with a 4-K blackbody load. The Low Noise Amplifier (LNA) at the heart of the FEM is based on indium phosphide High Electron Mobility Transistors (HEMTs). The radiometer incorporates a novel phase-switch design which gives excellent amplitude and phase match across the band. The noise temperature requirements are met within the measurement errors at the two frequencies. For the most sensitive LNAs, the noise temperature at the band centre is 3 and 5 times the quantum limit at 30 and 44 GHz respectively. For some of the FEMs, the noise temperature is still falling as the ambient temperature is reduced to 20 K. Stability tests of the FEMs, including a measurement of the 1/f knee frequency, also meet mission requirements. The 30 and 44 GHz FEMs have met or bettered the mission requirements in all critical aspects. The most sensitive LNAs have reached new limits of noise temperature for HEMTs at their band centres. The FEMs have well-defined linear polarization characteristcs.

The 30 and 44GHz Back End Modules (BEM) for the Planck Low Frequency Instrument are broadband receivers (20% relative bandwidth) working at room temperature. The signals coming from the Front End Module are amplified, band pass filtered and finally converted to DC by a detector diode. Each receiver has two identical branches following the differential scheme of the Planck radiometers. The BEM design is based on MMIC Low Noise Amplifiers using GaAs P-HEMT devices, microstrip filters and Schottky diode detectors. Their manufacturing development has included elegant breadboard prototypes and finally qualification and flight model units. Electrical, mechanical and environmental tests were carried out for the characterization and verification of the manufactured BEMs. A description of the 30 and 44GHz Back End Modules of Planck-LFI radiometers is given, with details of the tests done to determine their electrical and environmental performances. The electrical performances of the 30 and 44GHz Back End Modules: frequency response, effective bandwidth, equivalent noise temperature, 1/f noise and linearity are presented.

The SKADS Benchmark Scenario is an overall SKA concept which aims to meet as many as possible of the SKA requirements presented in the SKA reference design. The key element of the system design is the use of aperture array technology on all baselines below a frequency of 1 GHz which gives a field of view of 250 square degrees in the key mid-frequency band. At higher frequencies comparatively low-cost, small (6.1 m) antennas are proposed each equipped with a single wide-band feed. The detailed design of high frequency dishes and wide-band, single pixel feeds is likely under a highly complementary US TDP programme and elsewhere. This Scenario is presented in detail, concentrating in particular on the design of the key mid-frequency aperture array and drawing on the work of other projects for elements of the system outside of the expertise and scope of the SKADS project. Detailed costing of the design suggests strongly that the Benchmark Scenario is a practical and achievable implementation which delivers the scientific performance for the SKA. The “worst case” cost is estimated to be€ 1.91 Billion with an uncertainty of 9% costed for 2011. Further development of the Benchmark Scenario will include detailed scientific and astronomical evaluation and simulation together with cost optimisation and cost/performance tradeoffs.

Radio telescopes have traditionally used a single receiver at the focus, effectively giving a one-pixel image of the sky. The One Centimetre Receiver Array (OCRA) is a three-stage programme to develop multi-pixel arrays to be mounted at the focus of large radio telescopes. OCRA-f is the second phase, funded under the EU FARADAY project, and consists of a 10-beam array installed on a 32-metre radio telescope in Poland. It will produce Ka-band radio maps of the sky, acting as a ten-pixel radio camera. The paper describes a state-of-the-art all-MMIC receiver front-end developed using the lattice-matched indium phosphide foundry process of NGST, California. The effect of leakage on system noise temperature is described. Finally measurements are presented yielding an overall noise temperature of less than 21 kelvin over a 10 GHz bandwidth at Ka band.

Large ground-based radio telescopes are increasingly being equipped with multibeam feed systems to enable simultaneous observation of a larger part of the sky. The aim of the One Centimetre Receiver Array-f project, part of the European Commission funded FARADAY Programme, was to develop a high-quality science instrument to survey the sky at 1-cm wavelength, while developing technologies that would be applicable to future development of systems with 100 beams or more. A complete ten-beam Ka-band radiometer system is described, together with measured results at cryogenic temperatures. Performance compares well with that obtained with similar (non monolithic microwave integrated circuit) instruments produced for the Wilkinson microwave anisotropy probe and Planck satellites.

Aims. To measure the 30-GHz flux densities of the 293 sources in the Caltech-Jodrell Bank flat-spectrum (CJF) sample. The measurements are part of an ongoing programme to measure the spectral energy distributions of flat spectrum radio sources and to correlate them with the milliarcsecond structures from VLBI and other measured astrophysical properties.Methods. The 30-GHz data were obtained with a twin-beam di. erencing radiometer system mounted on the Torun 32-m telescope. The system has an angular resolution of 1.2'.Results. Together with radio spectral data obtained from the literature, the 30-GHz data have enabled us to identify 42 of the CJF sources as Giga-hertz Peaked Spectrum (GPS) sources. Seventeen percent of the sources have rising spectra (a > 0) between 5 and 30 GHz.

Historically radio telescope have mostly consisted of large dishes with a single feed system at the focus. Recently there has been a trend towards multi-beam systems to make more efficient radio maps of the sky. Three teams, funded under the EU FARADAY project, have designed receiver arrays developed using the lattice-matched indium phosphide foundry process of NGC, California. Receiver architecture and measured results are described.