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Introductory Analysis of Antenna Feeds and RF Networks

Ⅰ. The main points of antenna feeding during design:

1. Efficiency, gain, and absolute gain are very important for antenna feeding design.

2. The feeding impedance includes loss resistance and radiation resistance. The loss resistance is provided by the antenna components, and the feeding impedance is located at the input end of the signal to the antenna. Therefore, the loss and feeding impedance must work together to achieve normal operation of the antenna feeding.

3. The radiation resistance is provided by the antenna to the radiated power, i.e. the dissipated radiation power.

Ⅱ. The application of antenna feeding horn:

The microwave feedhorn is used to couple to the waveguide used in radar, line-of-sight microwave transmission, or radio astronomy. The feeding horn minimizes the mismatch loss between the antenna and the waveguide.

When the feeding horn is used for biased, parabolic or lens antennas, it is placed at the focus of the reflector. The characteristic of the feeding horn is usually chosen to make the 3 dB point of the horn radiation pattern fall on the edge of the reflector. When the shape of the antenna deviates from the dish antenna, the horn antenna needs to be shaped accordingly to properly illuminate the antenna.

Ⅲ. Common problems of antenna feeding and RF network:

1. Which components are related to the antenna feeding network?

Antenna feeds usually includes OMT, phase shifter, rotary joint, feeding horn, filter (i.e. duplexer), and bent waveguide and other components. These components are selected by the customer according to the system application.

2. What is the difference between a duplexer and a circulator?

A duplexer is a 3-port passive device that allows two different devices to share a common communication channel. It consists of two filters (low-pass, high-pass or band-pass) connected to a single antenna, operating at different frequencies. The signals input to filter 1 and filter 2 must be at different frequencies, and the difference in frequency should be large so that the waveguide filter can easily classify them.

A circulator is a 3-port device that allows a transmitter and a receiver to use a single antenna while working at the same/similar frequencies. It is a device that allows bi-directional communication on a single channel, isolating the receiver from the transmitter when transmitting pulses, and isolating the transmitter from the receiver when receiving pulses, allowing them to share the same antenna. There is no direct path between the transmitter and receiver in a circulator. It can be considered as a circulator.

3. What are the applications of phase shifters?

The microwave phase shifter is a key component in many RF and microwave systems. Applications include controlling the relative phase of the elements in phased array antennas in radar or controllable communication links, and offset loops used in high linearity amplifiers.

As the heart of the Dolph microwave antenna system, antenna feeding and RF network are designed by our experienced engineers who have been engaged in satellite communication and RF fields for many years. Available components include OMT (Orthogonal Mode Transducer), duplexer, filter, phase shifter, and horn antenna, covering different bands such as C band, Ku band, Ka band, S band. X-band and required dual-band and so on. Welcome to consult.

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