A waveguide antenna is an antenna that guides radio frequency energy from an air medium into a waveguide, and vice versa. Once the radio frequency energy is captured, the radio frequency energy is conducted through the waveguide interconnection, or picked up by the coaxial interface, and then transmitted through the coaxial assembly. The reverse is also true because the waveguide antenna is a symmetrical system. The frequency range and antenna polarization depend on the size and type of the waveguide antenna, of which there are many standard forms. As with any antenna, the following parameters are key information when choosing a waveguide antenna.

"Concept and Parameters of Waveguide Antenna"

Important waveguide antenna parameters

Frequency range (waveguide bandwidth or coaxial bandwidth of broadband waveguide antenna)

Gain

Beam width (horizontal beam width)

Beam height (vertical beam width)

impedance

Input standing wave ratio

Antenna radiation pattern

polarization

Interface (coaxial or waveguide)

size

weight

Input power processing

The frequency of the waveguide antenna is also limited by the size of the waveguide inside the antenna and the actual size of the antenna. In some cases, such as broadband antennas with coaxial interfaces, the frequency range is limited by the design of the antenna and the coaxial interface. In general, in addition to waveguide antennas with coaxial interfaces, waveguide antennas also have the advantages of high-power processing, enhanced shielding, and low-loss waveguide interconnection. In addition, the frequency operation of the waveguide antenna also depends on the actual size, and the size of the low-frequency waveguide antenna is often not practical in many applications.

There are several different types of waveguide antennas, and each type has its own specific advantages for a given set of applications. 

Common types include the following list:

Waveguide antenna type

Standard gain horn antenna

Cone horn antenna

Cone gain horn antenna

Probe

Lens horn antenna

Sector antenna

Omnidirectional antenna

Broadband Horn Antenna

Wide-angle scalar feed horn antenna

Circular scalar fed horn antenna

Dual polarization horn antenna

Dual polarization feed horn antenna

Dual polarization scalar feed horn antenna

Waveguide standard horn antenna, conical (circular) horn antenna, exponential (scalar) horn antenna and sector (sector or wide-angle) horn antenna

A horn antenna is a waveguide antenna with a metal horn shape, just like a music horn, hence its name. Horn antennas are directional antennas, essentially rectangular (standard or pyramid horn) antennas or circular (conical) antennas. These shapes can lead to different polarizations, linear polarization or circular polarization. The horn antenna can also be designed to have a curved side surface, which can have a pyramidal or conical cross section. This design can minimize internal reflections over a wide frequency range and make the impedance nearly constant. The fan-shaped horn may also be parallel to one side of the pyramidal horn instead of being flared, creating a fan-shaped beam pattern.

Waveguide gain antenna

The low loss of the waveguide antenna makes the overall directivity almost equal to the gain of the antenna. Therefore, if the directivity of the antenna is very narrow (depending on the shape and size of the antenna), these antennas may have a high gain.

Waveguide Probe Antenna

Waveguide probe antennas are usually designed to sample the radiated electromagnetic field of the antenna under test with minimal interference to the incident field. They are commonly used for near-field measurements of antenna structures.

Waveguide lens antenna

The lens antenna uses the characteristics of the lens (convergence and divergence) to focus the radio frequency energy captured by the waveguide antenna to a point source. The point source is usually a coaxial probe (receiver), and the waveguide antenna is used as a feed antenna. Lens antennas are generally used in applications that require wide bandwidth and high directivity antennas.

Omnidirectional waveguide antenna

The design of the omnidirectional waveguide antenna is to make the antenna radiation pattern radiate at 360 degrees, which is different from the fan-shaped or single-lobe horn antenna.

Broadband waveguide antenna

The design of the broadband waveguide antenna is to direct the radio frequency energy in the wide frequency band to the interface receiver (usually a coaxial cable), and the interface receiver can handle the bandwidth required by the antenna. The design consists of an exponentially inclined waveguide side and a plug-in interface for broadband operation.

Waveguide-fed antenna

Feed antennas are used to direct radio frequency energy to another antenna or receiver. Therefore, depending on the type of waveguide antenna, the waveguide antenna is sometimes called a feed antenna or a feed horn.

Dual polarization waveguide antenna

Dual-polarized waveguide antennas are designed to support linear and elliptical polarized waveforms.