A horn antenna is a surface feed antenna with a tapered circular or rectangular cross-section waveguide terminal. The horn antenna can be used as a stand-alone or feeder for a parabolic reflector antenna.

The horn antennas are mainly classified by shape, usage, and character. It is included but is not limited to asymmetrical horn antenna, broadband horn antenna, conical horn antenna, corrugated horn antenna, dual-polarization horn antenna, millimeter horn antenna, ridge horn antenna, standard gain horn antenna, symmetrical horn antenna, etc.

Horn antenna features circular symmetry, compact size, high efficiency, wide operating frequency ranges with deficient sidelobe level, cross-polarization level, and excellent phase characteristics. It is ideal and widely used for communication satellite, radar, radio astronomy, antenna testing, wireless networks, etc. 

How does the horn antenna work?

The horn antenna works by acting as an waveguide for the electromagnetic waves generated by the radio. The horn at the end of the antenna acts as a resonator, amplifying the radio signal. This amplification allows for a more excellent range of transmission or reception.

The main body of the horn antenna is to gradually expand the opening surface of the rectangular waveguide or circular waveguide. It can improve the matching between the waveguide and accessible space, making a low reflection coefficient. That means the horn radiates most of the energy transmitted in the waveguide with a little reflected signal.

The radiation field of the horn antenna can be calculated by the mouth field using the Huygens principle. The mouth surface field is determined by the size of the mouth surface of the horn and the propagation waveform.

The horn antenna can also examine material properties and beamwidths or measure power levels. The horn antenna is also valuable for EMC testing as a calibrator since a known amount of power is needed to measure emissions of electromagnetic compatibility (EMC).

Horn Antenna vs. Sector Antenna  

Both horn and sector antennas are widely used for fixed wireless signal coverage. However, there are some differences between the traditional sector antennas and symmetrical horn antennas.

Symmetrical horn antenna has a unique beamforming performance with no sidelobe and null signal. It can improve the efficiency of the communication system by 30% with high isolation and F/B. It’s ideal for high-density network deployment in urban areas. Compared with the traditional sector antenna, it’s a compact and lightweight design and much easier to install on the mast.

The sector antenna can cover a larger area with a much wider beamwidth for point-to-multipoint communication. However, the gain and beamwidth are not symmetrical across the operating frequency. It’s more suitable and cost-effective for wireless networks in rural and suburban areas. 

Horn Antenna vs. Parabolic Dish Antenna 

A horn antenna can act as a stand-alone antenna or feeder(feedhorn) for the large parabolic reflector antenna. In antenna measurement, only the horn antenna is used as a standard gain antenna for calibration and gain testing of other types of antennas. 

 As a stand-alone asymmetrical/symmetrical horn antenna, it features broadbands, 10-20dBi gain, and 30-90 degrees beamwidth. They are more suitable for point-to-multipoint communications. It can be deployed as a WiFi hotspot coverage in a community or area.

As a feedhorn, the horn antennas are widely used for giant parabolic reflector antennas in communication satellite, radar, radio astronomy, etc. The horn antenna has unique characteristics and functions that no other antenna can perform. 

A parabolic dish antenna uses a curved surface reflector with a parabola’s cross-sectional shape to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or parabolic dish. The main advantage of a parabolic antenna is that it has high directivity gain. It functions similarly to a searchlight or flashlight reflector to direct the radio waves in a very narrow beamwidth or only receive radio waves from one particular direction. Parabolic dish antennas have the highest gain during all the directional antenna types. It’s ideal for point-to-point communications and microwave backhauls networks. 

Horn Antenna Advantages & Disadvantages

The advantages and disadvantages of using horn antennas over other antennas include frequency ranges, gain, half-power beamwidth, efficiency, cost, size, and physical characteristics, etc.

Advantages:

• Directivity: Horn antennas have high levels of directivity due to their waveguide design. It can avoid unwanted signals and noise.
• Broadband: Horn antenna has a broader frequency band than any antenna.
• Higher gain: Horn antennas also have higher gain levels than most other antennas.
• High efficiency: Horn antennas are more efficient than other types of antennae, so they perform well at low frequencies and with more power. A horn antenna’s efficiency can reach 80%.
• Compact size and lightweight: Most of the horn antennas are compact size and lightweight. It can save a lot of freight costs & labor costs during the pandemic period.

Disadvantages

• Complexity: Horn antennas are pretty complex with a long lead-time on R&D.The design requires advanced knowledge in electromagnetism and wave propagation.
• High manufacturing cost: Building a horn antenna can be costly because it must be built from costly materials such as copper. It has to make high-cost die-casting aluminum tooling/mold for mass production due to its unique shape.