Abstract: The present invention relates to a switchable filter comprising: a filter unit in which a first filter group for filtering the frequency of a first frequency band is provided on one surface thereof and a second filter group for filtering the frequency of a second frequency band is provided on the other surface thereof on the basis of a center partition wall; and a frequency band switching unit, which moves to be adjacent to or separated from the one surface or the other surface of the filter unit, and thus converts a frequency band into the first frequency band or the second frequency band. Therefore, the deterioration of RF characteristics is prevented and selective conversion between frequency bands is facilitated.

Abstract: The present disclosure relates to a cavity filter assembly and, particularly, comprises: a filter body having a cavity, which is a predetermined space therein; and at least one resonance bar having a front end surface that forms a stamped part, which is a protruding surface protruding from the bottom surface of the filter body toward the cavity so as to be parallel to the bottom surface of the filter body in the cavity, for frequency tuning in the cavity, and having a tuning correction hole that penetrates the stamped part, wherein the resonance bar allows frequency tuning to be performed in the cavity through stamping on the outer surface of the stamped part from the outside of the filter body, and the tuned frequency can be corrected through the tuning correction hole, and thus the advantages of reducing the total weight and component costs of an antenna device and improving product productivity are provided.

Abstract: The present invention relates to a mask. The mask includes: a body part covering respiratory organs of a user; and a hanging part provided at each of both sides of the body part to allow the body part to be fixed to the respiratory organs of the user. The body part includes a chin cover part of a chin part, which forms a lower portion and surrounds chin of the user.

Abstract: A multi-band multiple-input multiple-output (MIMO) transmitting apparatus and method of using an analog optical repeater that relays a downstream signal and an upstream signal between a base station and a terminal is provided. A head end of the analog optical repeater converts a frequency of a signal through a frequency converter to prevent the signal from overlapping with other signals having the same frequencies of a downstream multi-band, and uses a band already used by an optical module, and thus does not need to secure an additional band in the optical module. Accordingly, signals at the same frequency input into the HE can be transmitted through the optical cable and to the RU without overlapping. A flow of upstream signals received from the terminal are handled and transmitted similarly to the downstream signals, but in the opposite direction, whereby multi-band MIMO is implemented.

Abstract: A multi-band multiple-input multiple-output (MIMO) transmitting apparatus and method of using an analog optical repeater that relays a downstream signal and an upstream signal between a base station and a terminal is provided. A head end of the analog optical repeater converts a frequency of a signal through a frequency converter to prevent the signal from overlapping with other signals having the same frequencies of a downstream multi-band, and uses a band already used by an optical module, and thus does not need to secure an additional band in the optical module. Accordingly, signals at the same frequency input into the HE can be transmitted through the optical cable and to the RU without overlapping. A flow of upstream signals received from the terminal are handled and transmitted similarly to the downstream signals, but in the opposite direction, whereby multi-band MIMO is implemented.