Due to the rapid development of technology in communication, there is an increasing need for antenna systems with good performance. As receiving and transmitting radio wave equipment, the antenna is a critical component of the whole system. The reflective surface antenna(parabolic dish antenna) has unique advantages, and it’s widely used in communication, radar, radio astronomy, etc. As the feed source or direct radiator of the whole reflector antenna, the horn antenna directly affects the performance of the entire reflector system.

When choosing a horn antenna, you need to focus on a couple of parameters based on your application. It’s included but not limited to frequency ranges, gain, polarization as well as the half-power beamwidth, etc.

Horn Antenna Frequency Ranges

Currently, most commercial fixed wireless services use C-band. With the increasing variety of communication services, Ku/Ka-band is gaining more and more attention after being fully developed by reducing the track spacing and adopting orthogonal polarization multiplexing and spatial multiplexing. In terms of bandwidth, Ku/Ka-band is much larger than C-band, especially Ka-band, so it is the primary band for the new generation of high-capacity communication systems.

Late in World War II, Germany first used a radar that operated at a wavelength of only 1.5 cm, called K-band radar. K is the initial of the German word Kurz (short). Unfortunately, the Germans’ frequency happened to be very easily absorbed by water vapor, making it unusable in foggy or rainy weather. Radars after World War II usually used Ku (K-under) band or Ka (K-above) band to avoid the water vapor absorption peak in the K band. The specific band division is shown in the table below:

Ku/Ka-band communication system can meet the high-capacity requirements of communication and can improve the system’s anti-interference, confidentiality, anti-destructiveness, flexibility, etc.

Horn Antenna Gain

As you already know that there are numerous types of horn antennas with diverse functionalities. The different antennas have varying applications and accordingly decided operating frequencies. Here the bandwidth and operating frequencies create a difference between their gains, not to forget the impact of horn antenna type. Consequently, the gain remains symmetrical throughout the waveguide.

Horn Antenna Polarization

As to the electromagnetic waves, polarization describes the trajectory of its electric field (or magnetic field) vector over the propagation cross-section with time. It is essential information that can be used except the time domain, frequency domain, and air domain of electromagnetic waves. The effective use of electromagnetic wave polarization information can significantly improve the identification and anti-jamming capability of intelligence radar, the resolution and anti-jamming capability of synthetic aperture radar (SAR), and the weather forecast accuracy of weather radar.

When it comes to the polarization of various horn antennas, there are three main polarity types. One is linear polarization, horizontal or vertical polarization. One is circular polarization, left-hand and right-hand circular polarized. The third is dual-polarization which is horizontal & vertical or +45°& -45°. Two types of dual-polarized polarization can be interchanged by adjusting the mounting angle of the waveguide.

• Linear Polarization Horn Antennas

Linear polarization is the most common polarization method for various horn antennas. Linear polarization has two polarities, horizontal and vertical (default). It’s included but not limited to the broadband horn antennas, conical horn antennas, corrugated horn antennas, dual-polarization horn antennas, millimeter horn antennas, ridge horn antennas and standard gain horn antennas, etc.

• Circular Polarization Horn Antennas

The most common circularly polarized horn antenna is the conical horn antenna. The axisymmetry of the circular waveguide horn allows it to handle any polarization excitation, including circular polarization. A single coaxial probe or waveguide feed can generate a linear polarization.

• Dual Polarization Horn Antennas

A dual-polarized antenna is an essential subsystem of dual-polarization radar or radio. The high efficiency polarization usually requires the antenna to have a low cross-polarization level and high polarization isolation level. The dual-polarization antenna array has two categories: waveguide dual-polarization and microstrip dual polarization. The waveguide dual polarity antenna array is more widely used at C band(4-8GHz) while the microstrip one is between Ku band and Ka band(18-40GHz).

Horn Antenna Radiation Patterns

The radiation pattern of horn antennas is a graphical representation of radiation strength and function direction. The field strength and sometimes radiation intensity goes into measuring the power of the radiation. For finding the radiation pattern;

• The antenna should find a location at the spherical polar coordinates system’s origin point.
• Different strengths at different field points on the imaginary concentric spherical surface.

Horn Antenna Beamwidth

The half-power beamwidth of a horn antenna has something significant with the horn antenna type, frequency range and gain. The higher the gain, the narrower the beamwidth and vice versa.

Horn Antenna Connector

N-Female : It’s a threaded N-type plug on one end and a pin on the other. The N-female connector suits the horn antennas with operating frequency under the Ku band( below 18GHz). It’s mainly used for standard gain horn antennas and dual-polarization horn antennas.

SMA Type:  The SMA-type connector is the most common connector type for various horn antennas. It includes SMA Male, SMA Female, RP-SMA Male and RP-SMA Female. The SMA-type connector suit the horn antennas that starting from 0.4 GHz and ending at 26.7 GHz.

2.40 and 2.92mm Type: They are smaller SMA-type connectors for microwave waveguide horn antennas, ranging from 18GHz to 44GHz.

Horn Antenna Waveguide

At the microwave band, various waveguides are used to transmit electromagnetic energy. The regular ones are rectangular and circular elliptical cross-section waveguides. Subsequently, people had discovered that waveguides with terminal openings could also radiate outward electromagnetic waves. That’s why a waveguide radiator appears, consisting of waveguide terminal openings. The change of feeder is a natural development of transmission line waveguides.

Waveguides perform a crucial role in the successful transmission of radioactive waves. They guide the radiation by preventing the rays from spreading here and there, leading to concentrated signal strength. The radiation waves coming through a waveguide ensure that they go to a designated direction with a stronger signal. Waveguide is the heart of the horn antenna. Different horn antennas have different waveguide sizes. It entirely depends on the operating frequency ranges.

Horn Antenna Waveguide Standards vs Frequencies vs Dimensions

There are three primary international standards and 34 waveguides for horn antennas worldwide. The below table shows the models, cut-off frequency, and dimensions based on the EIA Standard, British Standard, and IEC Standard: