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Any five antenna parameters

Short answer

Radiation pattern: graph of radiated field vs direction. Directivity: ratio of max radiation intensity to average (e.g., λ/2 dipole 1.64, 2.15 dBi). Gain: directivity including losses. Radiation efficiency: radiated power over input power. Half-power beamwidth: angle between −3 dB points (λ/2 dipole 78°).

Explain any five parameters of antenna.

Antenna parameters describe how well an antenna radiates or receives. Five important ones:

  1. Radiation pattern: a graph of the radiated field or power versus direction (θ, φ) in the far field. It shows the main lobe, side lobes, back lobe and nulls. E.g. short dipole: E ∝ sinθ (doughnut).

  2. Directivity (D): ratio of maximum radiation intensity to average radiation intensity:

D = 4π U_max / P_rad

Short dipole 1.5; λ/2 dipole 1.64 (2.15 dBi).

  1. Gain (G): directivity including losses: G = ηD = 4πU_max/P_in. Expressed in dBi.

  2. Radiation efficiency (η):

η = P_rad / P_in = Rr / (Rr + RL)

e.g. Rr = 73 Ω, RL = 2 Ω → 97.3 %.

  1. Half power beamwidth (HPBW): angle between the −3 dB points of the main lobe; short dipole 90°, λ/2 dipole 78°. Narrow beam → high directivity.

Other parameters: bandwidth, input impedance, polarization, effective aperture.

✓ Answer checked by Claude Opus 5.5 (high effort)

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