cascade.py File Reference

Functionality concerned with setting the radiative transfer cascade. More...

Functions
np.ndarray	gateau.cascade.johnson_nyquist_psd (np.ndarray f_src, float T)
	Johnson-Nyquist power spectral density. More...
tuple[np.ndarray, np.ndarray]	gateau.cascade.window_trans (np.ndarray f_src, float thickness, float tandelta, float neff, bool window_AR, float T_parasitic_refl, float T_parasitic_refr)
	Calculates the window transmission. More...
np.ndarray	gateau.cascade.eta_Al_ohmic (np.ndarray f_src)
	Calculate Ohmic losses for aluminium over array of sky frequencies. More...
np.ndarray	gateau.cascade.sizer (Union[np.ndarray, float] eta, np.ndarray f_src, np.ndarray f_eta=None)
	Resize efficiency term to new size. More...
list[dict[any, any]]	gateau.cascade.read_from_folder (str cascade_folder, str yaml_name)
	Generate a cascade list from a cascade folder. More...
None	gateau.cascade.save_cascade (list[dict[any, any]] cascade_list, str save_folder, str yaml_name)
tuple[np.ndarray, np.ndarray]	gateau.cascade.get_cascade (list[dict[str, any]] cascade_list, np.ndarray f_src)
	Calculate a cascade list, consisting of efficiency and psd per stage. More...

Variables
float	gateau.cascade.TCMB = 2.725

Detailed Description

Functionality concerned with setting the radiative transfer cascade.

Function Documentation

eta_Al_ohmic()

np.ndarray gateau.cascade.eta_Al_ohmic

(

np.ndarray

f_src

)

Calculate Ohmic losses for aluminium over array of sky frequencies.

Parameters

f_src

Numpy array containing source frequencies. Units: Hz

Returns

Array with eta values for Ohmic losses.

get_cascade()

tuple[np.ndarray, np.ndarray] gateau.cascade.get_cascade	(	list[dict[str, any]]	cascade_list,
		np.ndarray	f_src
	)

Calculate a cascade list, consisting of efficiency and psd per stage.

Parameters

cascade_list

List containing, per element, a dictionary containing the efficiency and coupling temperature of each stage in the cascade. For reflective stages, the dictionary should contain either: A single eta and temperature. This requires the following fieldnames in the dictionary: 'eta_coup' (scalar) and 'T_parasitic' (scalar). A tuple with efficiencies and frequencies at which these are defined, and a temperature. This requires the following fieldnames in the dictionary: 'eta_coup' (2-tuple with Numpy arrays) and 'T_parasitic' (scalar).

For refractive stages, the dictionary should contain:

• Thickness of dielectric in meters, fieldname 'thickness'.
• Loss tangent, fieldname 'tandelta'.
• Effective refractive index, fieldname 'neff'.
• Whether to use anti-reflective (AR) coating, fieldname 'Window_AR'.
• Temperature seen in reflection coming from the antenna, fieldname 'T_parasitic_refl'.
• Temperature seen in refraction, fieldname 'T_parasitic_refr'.

Aside from efficiencies and temperatures, each stage can have a name, set with fieldname 'name'. If multiple subsequent stages couple to the same temperature, they can also be grouped. The efficiencies will be precomposed and a total efficiency is calculated. Then, these multiple stages are merged into a single stage and treated as such. This significantly unburdens the CUDA calculation kernel and should hence be used. The fieldname for grouping is 'groupname'. Subsequent stages to be grouped together must have the same group name.

Parameters

f_src

Array with source frequencies. Units: GHz.

Returns

List with list of arrays containing efficiencies as first element, and list containing arrays of psd as second element.

johnson_nyquist_psd()

np.ndarray gateau.cascade.johnson_nyquist_psd	(	np.ndarray	f_src,
		float	T
	)

Johnson-Nyquist power spectral density.

Parameters

f_src	Source frequencies. Units: Hz.
T	Temperature. Units: K.

Returns

Power spectral density. Units: W / Hz.

read_from_folder()

list[dict[any, any]] gateau.cascade.read_from_folder	(	str	cascade_folder,
		str	yaml_name
	)

Generate a cascade list from a cascade folder.

The folder should contain a YAML file containing the cascade list. Any vector-valued efficiency terms should be provided inside the folder as a CSV file, with the first column containing frequencies at which the terms are evaluated and the second column containing the terms themselves. Then, the CSV can be referenced inside the YAML by passing the CSV name (including .csv) to the eta_coup field inside the YAML.

Parameters

cascade_folder	String containing path to folder containing cascade YAML and any related CSV files.
yaml_name	String containing the name of the YAML file containing the cascade.

Returns

List containing the cascade.

sizer()

np.ndarray gateau.cascade.sizer	(	Union[np.ndarray, float]	eta,
		np.ndarray	f_src,
		np.ndarray	f_eta = None
	)

Resize efficiency term to new size.

Used to vectorize or interpolate on efficiency terms.

If eta is a scalar, a constant eta array is returned with the same size as f_src.

If eta is an array with eta.size != f_src.size, an array containing frequencies at which eta is evaluated should also be passed. A 1D interpolation on f_src is then performed to evaluate eta on f_src.

If efficiency is array with same size as f_src, it is returned as-is.

Parameters

eta	Efficiency term of some stage.
f_src	Numpy array containing source frequencies. Units: Hz.
f_eta	Numpy array containing frequencies at which eta is evaluated. Units: Hz. Should only be passed when 1D interpolation is required in case eta.size != f_src.size. Defaults to None.

Returns

Array with eta values, depending on input (see above).

window_trans()

tuple[np.ndarray, np.ndarray] gateau.cascade.window_trans	(	np.ndarray	f_src,
		float	thickness,
		float	tandelta,
		float	neff,
		bool	window_AR,
		float	T_parasitic_refl,
		float	T_parasitic_refr
	)

Calculates the window transmission.

Parameters

f_src	Source frequencies. Units: Hz.
thickness	Thickness of the window/lens. Units: m.
tandelta	Loss tangent of window/lens dielectric.
neff	Refractive index of dielectric. Set to 1 to remove reflections. Units : None.
window_AR	Whether the window is supposed to be coated by Ar (True) or not (False).
T_parasitic_refl	Temperature of parasitic source seen in reflection, w.r.t. instrument.
T_parasitic_refr	Temperature of parasitic source seen in refraction..

Returns

List containing list of arrays of efficiencies as first element, and list of arrays of psd's seen by each stage as second element.