Telecommunications – Transmitter and receiver at same station – With transmitter-receiver switching or interaction prevention
Patent
1997-03-14
1999-10-05
Le, Thanh Cong
Telecommunications
Transmitter and receiver at same station
With transmitter-receiver switching or interaction prevention
455 83, 333134, H04B 148
Patent
active
059638540
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an antenna amplifier.
DESCRIPTION OF THE BACKGROUND ART
In mobile communication systems, it is normal for a fixed station to transmit within a given frequency range and to receive within a frequency range that differs from the transmitting range. In certain applications, both transmission and reception are effected with the same antennas. The reason for this is to be found in the general desire to operate from a base station in a mobile communications tower in an area that is divided into separate sectors while utilizing diversity. The use of separate antennas for transmission and reception would result in an excessively large number of antennas.
In view of the relatively long downleads that are involved in this regard, there is an interest in amplifying the received signals already in connection with and close to the antenna, particularly in the case of fixed tower-mounted stations. In this regard, it is necessary to mutually separate the received incoming signals with the aid of filters, which must have the highest quality in order to bring losses down to a minimum. In an earlier known construction, the transmitter signal has been separated from the receiver signal with the aid of two signal paths, one for the transmitter signal and one for the receiver signal, each of which is connected to respective antenna and uplead sides through a duplex filter. Each duplex filter is comprised of two filters tuned to respective transmission and reception frequency bands. The advantage with this construction is that only one downlead to the ground mounted station is required. However, it can also be chosen to uplead the transmission power and downlead the receiver signal in a respective coaxial cable, thereby enabling a saving in ground positioned filter stages.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved antenna amplifier. Among other things, it is desired to therewith improve the isolation or separation between transmitter and the receiver bands, therewith to reduce losses in the transmission bands and to reduce non-linearity in the transmitter band, and also to reduce the occurrence of spurious intermodulation products and to obtain the least possible reception noise factors and the most effective transmission emission and also to achieve low weight and small size.
Such advantages are achieved in accordance with the invention with an antenna amplifier of the kind defined below.
According to one embodiment of the invention, there is provided an antenna amplifier which includes sequentially in a row a first reception band filter, a transmission band filter and a second receiver band filter, said filters being built-up in a comb-line structure. An amplifier-connected output and input are provided at respective ends of the row. Coupling means are placed on both sides of the midway transmitter band filter for connection to an antenna and to a downlead to a fixed station. Also included is an arrangement in which the first and the second receiver band filter are placed side by side-in a respective cavity with the transmitter band filter mounted perpendicular thereto in a separate cavity, wherein the connection therebetween is effected via apertures and inputting first resonators.
An antenna amplifier of the kind in question is meant to be mounted in a tower, which may have a height of 60 meters, where servicing is effected by service personnel climbing a ladder and working outdoors. Accordingly, an object of the present invention is to provide an amplifier of the aforesaid kind which can be readily handled, easily replaced and which is effective in operation. It shall also be possible to mass-produce the antenna amplifier at reasonable cost, in view of the large number of amplifiers required to expand or extend mobile telephony traffic. The amplifier shall be easy to connect-up, insensitive, and as small and as light as possible.
An important aspect in this regard resides in the desire to fully utilize the possibilities that
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patent: 5109536 (1992-04-01), Kommrusch
patent: 5239279 (1993-08-01), Turunen et al.
patent: 5241693 (1993-08-01), Kim et al.
patent: 5604470 (1997-02-01), Atokawa
G.L. Matthaei et al., "Microwave Filters, Impedance-Matching Networks, and Coupling Structures", pp. 497-500, Artech House Books, Dedham, MA.
Andreasson Krister
Ghasemzadeh Farshid
Nystrom Mattias
Cong Le Thanh
LG Products AB
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