Introduction to the types and parameters of satellite high-frequency heads

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According to the structural shape, the high-frequency head can be divided into two types: single-polarization split type and dual-polarity feed integrated (LNBF). Among them, there are more types of dual-polarity feed integrated high-frequency heads. According to the local oscillator mode, it can be divided into single local oscillator and dual local oscillator. According to the output port, it can be divided into single output, dual output, multi-output, etc.
There is only one polarization oscillator, also known as a polarization needle, in the waveguide cavity of the single-polarization split high-frequency head. It can only receive one polarization signal. If you want to receive another polarization signal, you need to rotate the high-frequency head 90 degrees. Since there is no polarization conversion circuit inside the single-polarization high-frequency head, the signal loss is small, the gain and stability are high, and it is mostly used in engineering systems. Since the single-polarization high-frequency head adopts a split structure, it needs to be equipped with a feed source. The feed source output end is connected to the high-frequency head through a flange. The flanges are manufactured according to standard sizes. The flange of the C-band feed source is rectangular in shape, and the inner diameter is also rectangular, with a length × width of 58.2mm × 29.1mm; the flange of the Ku-band feed source is square in shape (see Figure 3), with a rectangular inner diameter, and a length × width of 19.1mm × 9.5mm. The length-to-width ratio of the inner diameter of the two feed sources is 2:1.

Commonly used C-band monopolar high-frequency heads such as GARDINER 3605 and ASKBC213 have good performance and a gain of about 65dB. In this way, when the indoor unit is far away from the receiving antenna, the received signal attenuation will be smaller.

The most common Ku-band monopolar high-frequency head is PBIPLK-900.
There are two mutually perpendicular probes inside the bipolar high-frequency head, which receive horizontal (H) and vertical (V) signals respectively, and there is a horizontal bar in between, which is an isolation needle and plays a role in polarization isolation. The bipolar single-output high-frequency head introduces a 13/18V electronic switching circuit into the cavity, automatically identifies the voltage sent by the receiver through the feeder, whether it is 18V or 13V, so as to select the horizontal or vertical polarization probe to work, thereby achieving the purpose of bipolar single output.

C-band bipolar high-frequency heads can generally use common products such as PAUXlS PX900, PBI Tubro-1800, Baichang OS222, etc., and the local oscillator frequency is the standard 5150MHz.

Ku-band dual-polarity high-frequency heads all adopt a standard center-feed ring-focusing integrated design. There are many varieties and models, such as the commonly used straight-head ASK Ku07 and the PBI Gold1040PF for positive-feed antennas.

1. C-band bipolar dual local oscillator single output high frequency head

The C-band bipolar dual local oscillator single output high frequency head uses two local oscillator frequencies of 5150MHz and 5750MHz to separately process the H and V polarization signals. The two polarization signals in the range of 3.6 to 4.2GHz are converted into non-overlapping intermediate frequencies of 950 to 1550MHz and 1550 to 2150MHz respectively, thereby realizing transmission in a common feeder line, and the receiver can receive two polarization signals at the same time.

Dual local oscillator high-frequency heads are mostly used in satellite intermediate frequency distribution systems or CATV front-end engineering systems. One high-frequency head can provide interference-free reception to multiple receivers through a power divider. Commonly used C-band bipolar dual local oscillator single-output high-frequency heads include PAUXIS PX-1200, PBI Tubro-2100, etc.

2. Ku-band bipolar dual local oscillator single output high-frequency head

The Ku-band bipolar dual local oscillator single output high-frequency head commonly has two local oscillator frequencies of 9.75/10.60GHz or 9.75/10.75GHz. It has a built-in 0/22k switching circuit, which selects its low and high local oscillators respectively through the 0/22kHz pulse output by the satellite receiver. At the same time, the 13/18V voltage of the satellite TV receiver can be used to switch the horizontal or vertical polarization of the satellite signal to achieve full-band reception of Ku-band programs.

Common Ku-band bipolar dual-local oscillator single-output high-frequency heads include ASKKU50 for forward-feed antennas, elbow (also known as L-shaped head) PBI (30ld 1040L 10M, etc.
There are two types of bipolar single-local oscillator dual-output high-frequency heads. One is that the high-frequency head uses two independent circuits on the same printed circuit board, the voltage stabilization circuit and the oscillation circuit are shared circuits, and share a feed source and probe. It can simultaneously receive dual-polarization satellite signals and output them in two independent ways. Each way can be switched horizontally and vertically without affecting each other, with minimal signal loss and high parameter stability. For example, the PBIGold-2050 used in the Ku band (see Figure 15). The other is that the horizontal and vertical polarizations are output through two ports respectively, and each port can only select one of the polarization signals. However, with a switching switch such as two-input (H, V) four-output or two-input six-output, it can also provide interference-free reception signals for four or six digital satellite receivers, such as the PBI used in the C band. Turbo-2200.
In order to enhance the band and port receiving function of the high-frequency head and reduce its installation volume, a composite high-frequency head has appeared on the market, and the common ones are as follows.

1. Ku/Ku composite high-frequency head

Ku/Ku composite high-frequency head is to integrate two Ku-band high-frequency heads with the same performance parameters, share one port, and complete the reception of Ku-band signals from two close satellites through one antenna. For example, the Thunder BOLT-21 dual-satellite high-frequency head (see Figure 19) contains a DiSEqC switching short circuit. Users can use it with an offset feed antenna to receive all Ku-band programs on the two satellites 146 degrees E and 138 degrees E (of course, the landing field strength of the two satellites to be received must meet the reception requirements).

2. C/Ku composite high-frequency head

By manufacturing the C-band high-frequency head and the Ku-band high-frequency head together, it is possible to complete the reception of all C-band and Ku-band signals on a satellite. For example, PBI Tubro-4200 (see Figure 17) is a combination of a bipolar single-output C-band high-frequency head with a local oscillator of 5150MHz and a bipolar single-output Ku-band high-frequency head with a local oscillator of 10.75GHz. Another example is PBITurbo-4400 (see Figure 18), which is a combination of a C-band dual-output high-frequency head Turbo-2200 and a Ku-band dual-output high-frequency head Gold. 2050. It integrates the horizontal and vertical polarization reception functions of C and Ku bands and has four independent output ports.

Reference address:Introduction to the types and parameters of satellite high-frequency heads

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