Antenna Module

Polarization Loss

The polarization loss between two antennas with given axial ratios is calculated using the standard formula for polarization mismatch:

\[\text{PLF} = \frac{1}{2} +\ \frac{1}{2} \frac{4 \gamma_1 \gamma_2 -\ (1-\gamma_1^2)(1-\gamma_2^2)}{(1+\gamma_1^2)(1+\gamma_2^2)}\]

where:

  • \(\gamma_1\) and \(\gamma_2\) are the voltage axial ratios (linear, not dB)

  • PLF is the polarization loss factor (linear)

The polarization loss in dB is then:

\[L_{\text{pol}} = -10 \log_{10}(\text{PLF})\]

For circular polarization, the axial ratio is 0 dB, and for linear polarization, it is >40 dB.

Dish Gain

The gain of a parabolic dish antenna is given by:

\[G = \eta \left(\frac{\pi D}{\lambda}\right)^2\]

where:

  • \(\eta\) is the efficiency factor (typically 0.55 to 0.70)

  • \(D\) is the diameter of the dish

  • \(\lambda\) is the wavelength

spacelink.core.antenna.polarization_loss(ar1, ar2)[source]

Calculate the polarization loss in dB between two antennas with given axial ratios.

Parameters:

  • ar1 (Decibels) – First antenna axial ratio in dB (amplitude ratio)

  • ar2 (Decibels) – Second antenna axial ratio in dB (amplitude ratio)

Returns:

Polarization loss in dB (positive value)

Return type:

Decibels

spacelink.core.antenna.dish_gain(diameter, frequency, efficiency)[source]

Calculate the gain in dB of a parabolic dish antenna.

Parameters:

  • diameter (Length) – Dish diameter

  • frequency (Frequency) – Frequency

  • efficiency (Dimensionless) – Antenna efficiency (dimensionless)

Returns:

Gain in decibels (dB)

Return type:

Decibels

Raises:

ValueError – If frequency is not positive