CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2019-0138282 filed on Nov. 1, 2019, in the Korean Intellectual Property Office, the disclosure of which is herein incorporated by reference in its entirety.

BACKGROUND

Field

The disclosure relates to a low noise block down converter for receiving satellite broadcasting and an antenna apparatus including the same, and more particularly, to a low noise block down converter for receiving satellite broadcasting and an antenna apparatus including the same, which can efficiently remove interference with a terrestrial transmission signal, such as, for example, a 5G mobile communication signal, using a built-in cavity waveguide band pass filter.

Description of Related Art

In general, for satellite broadcasting reception and satellite communication, a feed horn and a low noise block down converter (LNB) are installed in a receiving unit of an antenna apparatus having a dish-shaped reflector. A satellite signal collected by the reflector of the antenna apparatus as described above is transferred to the low noise block down converter through the feed horn, and the low noise block down converter low-noise-amplifies the satellite signal and removes an out-of-band signal from the amplified satellite signal. Thereafter, a mixer down-converts the frequency by mixing the satellite signal with a local oscillation signal of the low noise block down converter itself, and outputs the signal to a satellite communication terminal or a satellite broadcasting receiver.

On the other hand, Korea became the world's first country to start a 5G mobile communication service in the first half of 2019, and mobile communication companies worldwide, including mobile communication companies in the United States, have started or are preparing this service. However, because the 5G mobile communication frequency band (in Korea, 3.42 to 3.7 GHz) partially overlaps the C-band satellite broadcasting frequency band (in general, 3.4 to 4.2 GHz), and in particular, a 5G mobile communication signal is transmitted from a terrestrial base station, the signal strength is strong enough to interfere with reception of the C-band satellite broadcasting, and a low noise block down converter becomes in a saturated state to cause a problem that the reception of the satellite broadcasting is not possible.

To solve the above-described problem, an antenna apparatus has been used, in which an external cavity waveguide band pass filter is additionally installed at a front end of the low noise block down converter.

FIG. 1is a perspective view of an antenna apparatus including a low noise block down converter for receiving satellite broadcasting, coupled with an external cavity waveguide band pass filter in the related art,FIG. 2is a perspective view of an external cavity waveguide band pass filter in the related art, andFIG. 3is a graph illustrating a reflection loss and an insertion loss of an external cavity waveguide band pass filter in the related art.

With reference toFIGS. 1 to 3, in an antenna apparatus100including a low noise block down converter200for receiving satellite broadcasting, coupled with an external cavity waveguide band pass filter140in the related art, the external cavity waveguide band pass filter140serves to pass a signal of 3.8 to 4.2 GHz and to remove a signal of 3.42 to 3.7 GHz that is a 5G mobile communication frequency band in order to make it possible to receive the satellite broadcasting.

The external cavity waveguide band pass filter140as described above is of a cavity type using a metal block, and has a structure in which blocks of multiple orders are provided in a waveguide and metal rods are inserted into the blocks so as to pass a necessary frequency signal and not to pass an unnecessary frequency signal. However, because the external cavity waveguide band pass filter140as described above is expensive and has a large volume (120 mm×100 mm×70 mm), it has a low economic efficiency, and its installation work is difficult. Further, because the weight of the external cavity waveguide band pass filter140is heavy (650 g), it lays a burden on a support120supporting the feed horn130being coupled to the external cavity waveguide band pass filter140to cause the equipment maintenance to be difficult.

Further, the external cavity waveguide band pass filter140has an insertion loss (about 0.5 to 1.0 dB) by itself, and such an insertion loss is amplified by a low noise amplifier (LNA) in the low noise block down converter200for receiving the satellite broadcasting as well as it is added to a noise of the filter in the low noise block down converter200for receiving the satellite broadcasting to degrade the quality of the received satellite broadcasting signal.

SUMMARY

An aspect according to various embodiments of the disclosure is to provide a low noise block down converter for receiving satellite broadcasting and an antenna apparatus, which can facilitate an installation work and equipment maintenance with high economic efficiency, improve the quality of a received satellite broadcasting signal, and remove interference with a terrestrial transmission signal, such as, for example, a 5G mobile communication signal.

Another aspect according to various embodiments of the disclosure is to provide a low noise block down converter for receiving satellite broadcasting and an antenna apparatus, which can have a sufficient gain of an intermediate frequency signal, minimize amplification of an unnecessary frequency band by a low noise amplifier, and prevent the low noise amplifier from being saturated.

In order to achieve the above aspects, according to a first feature of the disclosure, a low noise block down converter for receiving satellite broadcasting includes an input terminal; a low noise amplifying unit including one or more low noise amplifiers configured to amplify a signal received from the input terminal, and a built-in cavity waveguide band pass filter configured to pass a frequency band being higher or lower than a frequency band of a predetermined terrestrial transmission signal among satellite broadcasting frequency bands of signals amplified by the one or more low noise amplifiers; and a mixer configured to convert the signal output from the low noise amplifying unit into an intermediate frequency signal by mixing the signal output from the low noise amplifying unit with a local oscillation signal.

Preferably, according to the disclosure, the mixer is an active mixer configured to amplify one or more of the signal output from the low noise amplifying unit and the intermediate frequency signal.

Further, according to a second feature of the disclosure, an antenna apparatus includes a reflector configured to concentrate radio waves through reflection; a feed horn configured to receive the radio waves concentrated by the reflector; and a low noise block down converter for receiving the satellite broadcasting, configured to convert a signal transferred from the feed horn into an intermediate frequency signal.

By using the low noise block down converter for receiving the satellite broadcasting and the antenna apparatus according to the embodiments of the disclosure, the following effects are achieved.

1. The installation work and equipment maintenance can be facilitated with the high economic efficiency, the quality of the received satellite broadcasting signal can be improved, and the interference with the terrestrial transmission signal, such as, for example, the 5G mobile communication signal, can be removed.

2. The sufficient gain of the intermediate frequency signal can be obtained, the amplifying of the unnecessary frequency band by the low noise amplifier can be minimized, and the low noise amplifier can be prevented from being saturated.

Effects that can be obtained in the disclosure are not limited to the above-described effects, and other unmentioned effects can be clearly understood by those of ordinary skill in the art to which the disclosure pertains from the following description.

