Frequency (pmrf.Frequency)

class pmrf.Frequency(start: float = 0, stop: float = 0, npoints: int = 0, unit: FrequencyUnitT | None = 'Hz')

Bases: Module

A frequency axis used to evaluate models over.

This class provides a container for a frequency band, defining the points at which network parameters are evaluated. The source code has been ported from the scikit-rf Frequency class but modified for JAX compatibility.

The primary purpose is to hold a vector of frequency points (f) and the corresponding frequency unit (unit). It provides numerous properties for accessing different representations of the frequency axis, such as angular frequency (w) and scaled frequency (f_scaled).

Examples

import pmrf as prf
import skrf as rf

# Create a frequency axis from 1 to 2 GHz with 101 points
freq = prf.Frequency(start=1, stop=2, npoints=101, unit='ghz')

# Access properties like the frequency vector in Hz or radians/sec
print(f"Frequency points in Hz: {freq.f[:5]}...")
print(f"Angular frequency in rad/s: {freq.w[:5]}...")

# Convert to a scikit-rf Frequency object
skrf_freq = freq.to_skrf()
print(f"Type after conversion: {type(skrf_freq)}")

# Create from a scikit-rf Frequency object
freq_from_skrf = prf.Frequency.from_skrf(skrf_freq)

Frequency initializer.

Creates a Frequency object from start/stop/npoints and a unit. Alternatively, the class method from_f() can be used to create a Frequency object from a frequency vector instead.

Parameters:

start (number, optional) – Start frequency in units of unit. Default is 0.
stop (number, optional) – Stop frequency in units of unit. Default is 0.
npoints (int, optional) – Number of points in the band. Default is 0.
unit (string, optional) – Frequency unit of the band: ‘Hz’, ‘kHz’, ‘MHz’, ‘GHz’, ‘THz’. This is used to create the attribute f_scaled. It is also used by the Network class for plots vs. frequency. Default is ‘Hz’.

Notes

The attribute unit sets the frequency multiplier, which is used to scale the frequency when f_scaled is referenced.

The attribute unit is not case sensitive. Hence, for example, ‘GHz’ or ‘ghz’ is the same.

See also

from_f: constructs a Frequency object from a frequency vector instead of start/stop/npoints.
unit: frequency unit of the band

Examples

>>> wr1p5band = Frequency(start=500, stop=750, npoints=401, unit='ghz')
>>> logband = Frequency(1, 1e9, 301, sweep_type='log')

Construct Frequency object from a frequency vector.

The unit is set by kwarg ‘unit’.

Parameters:

f_scaled (scalar or array-like) – Frequency vector in the units of unit.
unit (FrequencyUnitT, optional) – Frequency unit of the band. Default is None (defaults to ‘Hz’).

Returns:

The instantiated Frequency object.

Return type:

Frequency

Examples

>>> f = np.linspace(75,100,101)
>>> rf.Frequency.from_f(f, unit='GHz')

static from_skrf(skrf_frequency, *, unit=None) → Frequency

Create a from pmrf.frequency.Frequency from a skrf.Frequency object.

Parameters:: skrf_frequency (skrf.Frequency) – The scikit-rf Frequency object.
Returns:: The equivalent pmrf Frequency object.
Return type:: Frequency

Elementwise addition on frequency values.

Parameters:: other (Frequency or ArrayLike) – The addend. If a Frequency, frequencies are added elementwise; otherwise other is broadcast as needed.
Returns:: A new object with updated frequency vector.
Return type:: Frequency

Elementwise division on frequency values (Python 2 style alias).

Parameters:: other (Frequency or ArrayLike) – The divisor. If a Frequency, divide elementwise; otherwise other is broadcast.
Returns:: A new object with updated frequency vector.
Return type:: Frequency

Elementwise floor division on frequency values.

Parameters:: other (Frequency or ArrayLike) – The divisor.
Returns:: A new object with updated frequency vector.
Return type:: Frequency

__getitem__(key: str | int | slice) → Frequency

Slices a Frequency object based on an index, or human readable string.

Parameters:: key (str, int, or slice) – if int, then it is interpreted as the index of the frequency if str, then should be like ‘50.1-75.5ghz’, or just ‘50’. If the frequency unit is omitted then unit is used.

Examples

>>> b = rf.Frequency(50, 100, 101, 'ghz')
>>> a = b['80-90ghz']
>>> a.plot_s_db()

__len__() → int

Return the number of frequency points.

Returns:: Length of the frequency vector.
Return type:: int

Elementwise modulo on frequency values.

Parameters:: other (Frequency or ArrayLike) – The modulus.
Returns:: A new object with updated frequency vector.
Return type:: Frequency

Elementwise multiplication on frequency values.

Parameters:: other (Frequency or ArrayLike) – The multiplier. If a Frequency, multiply elementwise; otherwise other is broadcast.
Returns:: A new object with updated frequency vector.
Return type:: Frequency

Reflected elementwise multiplication on frequency values.

Parameters:: other (Frequency or ArrayLike) – The multiplier.
Returns:: A new object with updated frequency vector.
Return type:: Frequency

Elementwise subtraction on frequency values.

Parameters:: other (Frequency or ArrayLike) – The subtrahend. If a Frequency, frequencies are subtracted elementwise; otherwise other is broadcast.
Returns:: A new object with updated frequency vector.
Return type:: Frequency

Elementwise true division on frequency values.

Parameters:: other (Frequency or ArrayLike) – The divisor. If a Frequency, divide elementwise; otherwise other is broadcast.
Returns:: A new object with updated frequency vector.
Return type:: Frequency

to_skrf()

Convert this from pmrf.frequency.Frequency object to a skrf.Frequency object.

Returns:: The equivalent scikit-rf Frequency object.
Return type:: skrf.Frequency

property center: float

The center frequency in Hz.

Returns:: The exact center frequency in Hz.
Return type:: float

property center_idx: int

The index of the frequency point closest to the center.

Returns:: Index of the center frequency.
Return type:: int

property center_scaled: float

The center frequency in the specified unit.

Returns:: The exact center frequency in the specified unit.
Return type:: float

property df: Array

The gradient of the frequency vector, in Hz.

Returns:: Gradient of frequency.
Return type:: jnp.ndarray

property df_scaled: Array

The gradient of the scaled frequency vector.

Returns:: Gradient of scaled frequency.
Return type:: jnp.ndarray

property dw: Array

The gradient of the angular frequency vector, in rad/s.

Returns:: Gradient of angular frequency.
Return type:: jnp.ndarray

f: array: The frequency vector in Hz.

property f_scaled: Array

The frequency vector in the specified unit.

Returns:: A frequency vector in the specified unit.
Return type:: jnp.ndarray

property multiplier: float

The multiplier to convert from the specified unit back to Hz.

Returns:: Multiplier for this frequency’s unit.
Return type:: float

property npoints: int

The number of points in the frequency axis.

Returns:: Number of points.
Return type:: int

property span: float

The frequency span (stop - start) in Hz.

Returns:: Span in Hz.
Return type:: float

property span_scaled: float

The frequency span (stop - start) in the specified unit.

Returns:: Span in units.
Return type:: float

property start: float

The starting frequency in Hz.

Returns:: Start frequency.
Return type:: float

property start_scaled: float

The starting frequency in the specified unit.

Returns:: Scaled start frequency.
Return type:: float

property step: float

The frequency step size in Hz for evenly spaced sweeps.

Returns:: Step size in Hz.
Return type:: float

property step_scaled: float

The frequency step size in the specified unit for evenly spaced sweeps.

Returns:: Step size in units.
Return type:: float

property stop: float

The stop frequency in Hz.

Returns:: Stop frequency.
Return type:: float

property stop_scaled: float

The stop frequency in the specified unit.

Returns:: Scaled stop frequency.
Return type:: float

unit: str: The frequency unit. Possible options are “Hz”, “kHz”, “MHz”, “GHz” or “THz”.

property w: Array

The angular frequency vector in radians/s.

Angular frequency is defined as \(\omega=2\pi f\).

Returns:: Angular frequency in rad/s.
Return type:: jnp.ndarray