123 lines
4.0 KiB
Rust
123 lines
4.0 KiB
Rust
//! Tests for antenna gain.
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//!
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//! 天线增益的测试。
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use apsis_rf::{DIPOLE_OVER_ISOTROPIC_DB, Gain, HALF_WAVE_DIPOLE_RATIO};
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use core::f64::consts::PI;
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const TOLERANCE: f64 = 1e-9;
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#[test]
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fn named_gains_match_their_definitions() {
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assert_eq!(Gain::ISOTROPIC.ratio(), 1.0);
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assert_eq!(Gain::ISOTROPIC.dbi(), Some(0.0));
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assert!(Gain::ISOTROPIC.dbd().expect("positive") < 0.0);
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// The linear ratio and the decibel offset are derived from each other,
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// so the two must agree.
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// 线性比值与分贝偏移由彼此导出，故二者必须一致。
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assert!((Gain::HALF_WAVE_DIPOLE.ratio() - HALF_WAVE_DIPOLE_RATIO).abs() < 1e-15);
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assert!(
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(Gain::HALF_WAVE_DIPOLE.dbi().expect("positive") - DIPOLE_OVER_ISOTROPIC_DB).abs() < 1e-12
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);
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assert!(Gain::HALF_WAVE_DIPOLE.dbd().expect("positive").abs() < 1e-9);
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}
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#[test]
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fn a_dipole_gain_is_zero_dbd_and_positive_dbi() {
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let gain = Gain::from_dbd(0.0).expect("finite reading");
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assert!((gain.ratio() - Gain::HALF_WAVE_DIPOLE.ratio()).abs() < 1e-12);
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assert!((gain.dbd().expect("positive")).abs() < 1e-12);
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assert!((gain.dbi().expect("positive") - DIPOLE_OVER_ISOTROPIC_DB).abs() < 1e-9);
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}
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#[test]
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fn decibel_forms_round_trip() {
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for dbi in [-10.0, -3.0, 0.0, 3.0, 20.0, 45.0] {
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let gain = Gain::from_dbi(dbi).expect("finite reading");
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assert!(
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(gain.dbi().expect("positive") - dbi).abs() < 1e-9,
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"dbi {dbi}"
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);
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}
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for dbd in [-5.0, 0.0, 10.0, 20.0] {
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let gain = Gain::from_dbd(dbd).expect("finite reading");
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assert!(
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(gain.dbd().expect("positive") - dbd).abs() < 1e-9,
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"dbd {dbd}"
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);
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}
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}
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#[test]
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fn dbd_and_dbi_differ_by_the_dipole_offset() {
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let gain = Gain::from_dbi(12.0).expect("finite reading");
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assert!(
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(gain.dbi().expect("positive") - gain.dbd().expect("positive") - DIPOLE_OVER_ISOTROPIC_DB)
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.abs()
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< 1e-9
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);
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}
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#[test]
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fn non_finite_readings_are_rejected() {
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assert_eq!(Gain::from_dbi(f64::NAN), None);
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assert_eq!(Gain::from_dbi(f64::INFINITY), None);
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assert_eq!(Gain::from_dbd(f64::NAN), None);
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}
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#[test]
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fn effective_aperture_follows_the_standard_relation() {
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// A gain of one has an aperture of lambda^2 / (4 pi).
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// 增益为一的孔径为 lambda^2 / (4 pi)。
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let gain = Gain::ISOTROPIC;
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let aperture = gain.effective_aperture(0.3).expect("valid wavelength");
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assert!((aperture - 0.3 * 0.3 / (4.0 * PI)).abs() < TOLERANCE);
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}
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#[test]
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fn a_larger_wavelength_needs_a_larger_aperture() {
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let gain = Gain::from_dbi(30.0).expect("finite reading");
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let small = gain.effective_aperture(0.01).expect("valid");
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let large = gain.effective_aperture(0.1).expect("valid");
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assert!(large > small);
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// The aperture grows with the square of the wavelength.
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// 孔径随波长的平方增大。
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assert!((large / small - 100.0).abs() < 1e-6);
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}
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#[test]
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fn aperture_and_gain_round_trip() {
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let gain = Gain::from_dbi(33.0).expect("finite reading");
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let wavelength = 0.025;
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let aperture = gain.effective_aperture(wavelength).expect("valid");
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let recovered = Gain::from_effective_aperture(aperture, wavelength).expect("valid");
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assert!((recovered.ratio() - gain.ratio()).abs() < 1e-6);
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}
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#[test]
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fn invalid_aperture_arguments_are_rejected() {
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assert_eq!(Gain::ISOTROPIC.effective_aperture(0.0), None);
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assert_eq!(Gain::ISOTROPIC.effective_aperture(-1.0), None);
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assert_eq!(Gain::ISOTROPIC.effective_aperture(f64::NAN), None);
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assert_eq!(Gain::from_effective_aperture(1.0, 0.0), None);
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assert_eq!(Gain::from_effective_aperture(-1.0, 1.0), None);
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}
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#[test]
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fn decibel_conversion_is_available() {
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let gain = Gain::from_dbi(10.0).expect("finite reading");
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let decibel = gain.as_decibel().expect("positive");
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assert!((decibel.db() - 10.0).abs() < 1e-9);
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}
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#[test]
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fn default_is_isotropic() {
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assert_eq!(Gain::default(), Gain::ISOTROPIC);
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}
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#[test]
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fn display_prefers_dbi() {
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assert_eq!(Gain::ISOTROPIC.to_string(), "0 dBi");
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}
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