Communications: radio wave antennas – Antennas – Switching between antennas and lines
Patent
1997-02-25
1999-08-03
Wong, Don
Communications: radio wave antennas
Antennas
Switching between antennas and lines
455 78, H01Q 324
Patent
active
059331224
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an antenna switch for wireless antenna diversity telecommunications devices with two antennas.
Wireless antenna diversity telecommunications devices are for example, wireless TDMA (Time Division Multiple Access) telecommunications devices according to the DECT standard (Digital European Cordless Telecommunication; cf. Nachrichtentechnik Elektronik (Telecommunication Electronics), Berlin, year 42, No. 1, 1-2/1992, pages 23 to 29, U. Pilger: "Struktur des DECT-Standards") or according to the GSM Standard (Groupe Speciale Mobile or Global Systems for Mobile Communication; cf. Informatik Spektrum (Computing Publication), Springer Verlag Berlin, year 14, 1991, No. 3, pages 137 to 152, A. Mann: "Der GSM-Standard--Grundlage fur digitale europaische Mobilfunknetze"). Wireless antenna diversity telecommunications devices with two antennas are known from International Application WO/94/10812 (FIGS. 1 and 2 with the associated description). The known antenna diversity radio transceiver has an antenna switch with two in-series switching elements (Diversity Switch DS and T/R Switch T/R-S according to FIG. 2 in International Application WO 94/10812) for switching over between the two antennas (implementation of "antenna diversity") and switching over between transmission and reception mode of the transceiver.
FIG. 1 shows the basic circuit diagram of such a cascade antenna switch 1, which has two in-series switching elements, a first switching element SE-I and a second switching element SE-II. These switching elements SE-I and SE-II switch through selectively a first signal path SW1 from a transmitter TR to a first transmission/reception antenna A1, a second signal path SW2 from the transmitter TR to a second transmission/reception antenna A2, a third signal path SW3 from a receiver RE to the first transmission/reception antenna A1 and a fourth signal path SW4 from the receiver RE to the second transmission/reception antenna A2. With this cascade configuration, switching losses occur at each switching element SE-I, SE-II for the implementation of the switching functions described above. These switching losses unnecessarily reduce the transmission power irradiated and the reception sensitivity of the transceiver.
SUMMARY OF THE INVENTION
It is an object of the present invention to minimize switching losses occurring with two antennas in antenna switches for wireless antenna diversity telecommunications devices.
In general terms the present invention is an antenna switch for wireless antenna diversity telecommunications devices having two transmission/reception antennas. In the antenna switch there are four signal paths that can be switched through selectively. A first signal path is from a transmitter to a first transmission/reception antenna, a second signal path is from the transmitter to a second transmission/reception antenna, a third signal path is from a receiver to the first transmission/reception antenna and a fourth signal path is from the receiver to the second transmission/reception antenna. An electronic switching element is arranged in each signal path. The switching elements are connected together to form a ring circuit. In alternative embodiments of the present invention the switching elements are PIN diodes or switching diodes.
This object is achieved on the basis of the antenna switch defined in the preamble of patent claim 1 by means of the features specified in the characterizing part of patent claim 1.
In the antenna switch of the present invention for wireless antenna diversity telecommunications devices with two transmission/reception antennas (for example a base station of a DECT cordless telephone), each of the switching functions assigned to the antenna switch utilize respectively only one single electronic switching element. The switching element can be, for example, as a PIN diode or switching diode arranged in a ring circuit. With the present invention switching losses which occur may be reduced by half in comparison with known antenna s
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patent: 4412223 (1983-10-01), Kautz
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patent: 5491723 (1996-02-01), Diepstraten
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Informatik Spektrum, (Computing Publication), Springer Verlag Berlin, Jun. 1991, year 14, No. 3, pp. 137 to 152, A. Mann: "Der GSM-Standard--Grundlage fur digitale europaische Mobilfunknetze".
DECT standard (Digital European Cordless Telecommunication); Nachrichtentechnik Elektronik (Telecommunication Electronics), 42 (1992). No. 1, Jan./Feb. 1992, pp. 23 to 29, U. Pilger: "Struktur des DECT-Standards".
Detering Volker
Lepping Jurgen
Sauer Jurgen
Ho Tan
Siemens Aktiengesellschaft
Wong Don
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