A Wave Approach to the Noise Properties of Linear Microwave Devices

Meys, René

doi:10.1109/tmtt.1978.1129303

Cited by 128 publications

(100 citation statements)

References 2 publications

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“…System noise couples across the parallel paths via internal reflections at the antenna and components in the receiver chains to give an additive spurious component in the measurement. This is shaped by the frequency dependence of Γ c and the relative path delay with which the direct and reflected signals arrive at the correlation spectrometer (Meys 1978).…”

Section: The Receivermentioning

confidence: 99%

First Results on the Epoch of Reionization from First Light with SARAS 2

Singh

Subrahmanyan

Shankar

et al. 2017

ApJL

138

115

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Long wavelength spectral distortions in the Cosmic Microwave Background arising from the 21-cm transition in neutral Hydrogen are a key probe of Cosmic Dawn and the Epoch of Reionization. These features may reveal the nature of the first stars and ultra-faint galaxies that transformed the spin temperature and ionization state of the primordial gas. SARAS 2 is a spectral radiometer purposely designed for precision measurement of these monopole or all-sky global 21-cm spectral distortions. We use 63 hr night time observing of the radio background in the frequency band 110-200 MHz with the radiometer deployed at the Timbaktu Collective in Southern India to derive likelihoods for plausible redshifted 21-cm signals predicted by theoretical models. First light with SARAS 2 disfavors the class of models that feature weak X-ray heating (with f X ≤ 0.1) and rapid reionization (with peak dT b dz ≥ 120 mK per unit redshift interval ).

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Section: The Receivermentioning

confidence: 99%

First Results on the Epoch of Reionization from First Light with SARAS 2

Singh

Subrahmanyan

Shankar

et al. 2017

ApJL

138

115

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“…4: stray capacitance, lead resistance and inductance must be added. The effects of additional elements on the scattering and correlation matrices are computed by applying embedding calculations (5)- (9); the equivalent circuit of Fig. 4 is considered embedded in a subcircuit consisting of the additional elements.…”

Section: Component Modelingmentioning

confidence: 99%

Wave techniques for noise modeling and measurement

Wedge

Rutledge

1992

IEEE Trans. Microwave Theory Techn.

158

118

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Abstract-The noise wave approach is applied to analysis, modeling, and measurement applications. Methods are presented for the calculation of component and network noise wave correlation matrices. Embedding calculations, relations to twoport figures-of-merit, and transformations to traditional representations are discussed. Simple expressions are derived for MESFET and HEMT noise wave parameters based on a linear equivalent circuit. A noise wave measurement technique is presented and experimentally compared with the conventional method.

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“…By inserting a cable between the mismatched noise source and LNA, the periodic results in a noise-temperature curve like a standing wave on the frequency axis. Assumed to be frequency independent, the four noise parameters can then be derived from the matched and mismatched noise temperatures [8], [9]. Intuitively, for a periodic , the corresponding mismatched noise temperature curve can be characterized by three variables, i.e., magnitude, phase, and average value.…”

Section: B Analytical Narrow-band Frequency-variation Methodsmentioning

confidence: 99%

“…1). Mathematically, the noise temperature can be expressed as (8) If this is periodic and comes from a lossless input cable with length , we can write (9) where is the speed of light in the cable, and is as defined above.…”

Section: B Analytical Narrow-band Frequency-variation Methodsmentioning

confidence: 99%

A Novel Wide-Band Noise-Parameter Measurement Method and Its Cryogenic Application

Weinreb

2004

IEEE Trans. Microwave Theory Techn.

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Abstract-The concept of using a long mismatched transmission line to measure noise parameters has been known for some time. However, it has been limited to narrow-bandwidth applications, and a wide-band extension has never been reported. In order to measure the cryogenic noise parameters of a wide-band low-noise amplifier (LNA), a wide-band frequency-variation method is proposed. In this method, the four noise parameters at each frequency are derived numerically from a set of matched and mismatched noise temperatures measured within a surrounding frequency-sampling window. By scanning this frequency-sampling window, noise parameters over a wide frequency range can be obtained. Since this approach can be easily incorporated into existing noise measurement systems, a tuner is not required, and the technique can be applied to a cryogenic amplifier. This paper details the theory, implementation, and verification of this new method. The measured noise parameters of a cryogenic wide-band LNA are presented.Index Terms-Frequency-variation method, noise-parameter measurement.

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A Wave Approach to the Noise Properties of Linear Microwave Devices

Cited by 128 publications

References 2 publications

First Results on the Epoch of Reionization from First Light with SARAS 2

First Results on the Epoch of Reionization from First Light with SARAS 2

Wave techniques for noise modeling and measurement

A Novel Wide-Band Noise-Parameter Measurement Method and Its Cryogenic Application

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