Standard Gain Horn (SGH) is a kind of precisely designed and calibrated waveguide aperture antenna. It delivers accurate, stable and calculable gain within the specified frequency band. As a primary reference standard for microwave and millimeter-wave measurements, it is known as “the ruler for microwave measurement”.
Basic Structure
- Feeding Waveguide: Standard rectangular waveguide for TE10 mode transmission
- Tapered Horn Section: Gradually flared on E-plane and H-plane to form a pyramidal structure (the most widely adopted type)
- Aperture: Rectangular radiation opening, whose dimensions determine gain and beamwidth
- Flange Interface: Standard waveguide flange to ensure interchangeability
Working Principle
- Guided Wave to Free-space Wave Conversion: The TE10 mode in the waveguide transits smoothly to free space through the tapered section, achieving superior impedance matching (VSWR＜1.2~1.3), low reflection and high radiation efficiency.
- Aperture Field Homogenization: The tapered structure realizes approximately uniform field distribution on the aperture with minor phase error, featuring narrow main lobe and low sidelobe level (typical ≤ -20 dB).
- Precisely Calculable Gain: Gain is determined by aperture area, efficiency and wavelength. The deviation between theoretical value and measured data is ≤±0.5 dB, making it ideal for reference antenna applications.
Pyramidal Horn Antenna: Features a rectangular internal cross-section and is generally matched with rectangular waveguides.
Sectoral Horn Antenna: Only one side flares outward while the other side remains parallel to the original waveguide plane, classified into E-plane sectoral horn and H-plane sectoral horn.
Conical Horn Antenna: Adopts a circular cross-section and is commonly used with circular waveguides.
Corrugated Horn Antenna: Equipped with axial grooves on the inner wall. It exhibits wide bandwidth, low sidelobes and nearly symmetric E/H-plane beamwidths, widely applied as feed horns for satellite antennas and radio telescopes.
Lens Horn Antenna: A dielectric lens is mounted at the horn aperture to convert curved wavefront into plane wavefront.
Dual-Ridge Horn Antenna: Primarily applied in electromagnetic compatibility (EMC) testing.
