AN ANTENNA UNIT

Abstract: In an antenna unit provided to amplify a received signal and retransmit the same signal amplified the antennas are formed directly on an integrated circuit. In a preferred embodiment the antennas are directional patch antennas which are provided at different sides of the integrated circuit, whereby the integrated circuit itself acts as an isolator between the two antennas. By means of locating the antennas directly on the integrated circuit lines between the antenna and the amplifier are avoided, which in turn significantly reduces the attenuation which takes place in conventional repeaters and the like.

Description: AN ANTENNA UNIT TECHNICAL FIELD The present invention relates to an antenna unit. In particular the present invention relates to an antenna unit for use in a wireless computer network or in a radio communication system. BACKROUND OF THE INVENTION AND PRIOR ART In many applications it is of importance to forward a radio signal. Examples of such applications include wireless local area network (LAN) a DECT system, or a GSM system. In a wireless access network, such as wireless Internet, there is also a need to amplify and forward radio signals. The most commonly used conventional way of achieving such a forwarding function is to locate a so-called repeater in the network. A repeater is a device comprising two antennas mounted on a common housing and which antennas via a feeding line are connected to an amplifier unit with associated logic and power supply. A problem associated with conventional devices for forwarding a data or telecommunication signal is that they generates a relatively large amount of radiation and thus demands a relatively high power to be supplied. A large output power leads to a problem of providing efficient cooling for these devices. For this reason they can not be made very small which is desirable in many cases. Also, the power losses are large in conventional repeater devices, which further reduce their performance. Further more, the high output power result in a large field of noise around a device of conventional type, which not either is desirable. This is particularly a problem in offices where many wireless networks, for example LAN and DECT systems appear side by side and have many simultaneous users. In such environments the total radiation can exceed the maximum value of allowed radiation in accordance with working environment legislation etc . SUMMARY It is an object of the present invention to provide a device for forwarding data and telecommunication signals which requires less power to be supplied and which also emits a lower amount of radiation. This object and other objects are obtained by an amplifier and at least two antennas provided directly on an integrated circuit (IC) , the antennas being located on different sides of the integrated circuit, the integrated circuit thereby acting as an isolator between the two antennas . In a preferred embodiment the antennas are directional patch antennas. Thus, a radio signal is received by the patch antenna on one side, is amplified in an amplifying unit and retransmitted via the antenna provided on the other side . By means of locating the antennas directly on the integrated circuit no lines needs to be provided between the antenna and the amplifier, which in turn significantly reduces the attenuation in conventional repeaters and the like. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described in more detail and with reference to the accompanying drawings, in which: - Fig. 1 is a schematic block diagram of an antenna for amplifying a signal. - Fig. 2 is a view in perspective of the antenna in Fig. 1. - Fig. 3 is a more detailed block diagram of an antenna for amplifying a signal, and - Fig. 4 shows an amplifier unit provided to establish a connection between a central base station and a client. DESCRIPTION OF PREFERRED EMBODIMENTS In Fig. 1 a block diagram of an antenna unit 101 for amplifying a signal is shown. The entire antenna 101 is integrated in the one and same circuit, which preferably can be formed as a multi chip module (MCM) or as an ASIC. The antenna 101 comprises two filter units 103 and 105, respectively. The filter units are directly connected to patch antennas 107 and 109, respectively located back to back so that the radiation from the two antennas 107 and 109 are directed in essentially the opposite directions. The filter unit 103 and 105 are provided to let through signals having a frequency within a certain range both in the upstream and downstream direction. The antenna unit 101 further comprises a control unit 111 and a unit 113 and a unit 115 for upstream and downstream signal amplification, respectively. The unit 101 is provided to amplify a signal received by a first antenna and retransmit the same signal via the second antenna after having amplified the received signal by a suitable factor. The control unit 111 is connected to the amplifiers 113 and 115 via a common bus 116. The control unit 111 inter alia controls the amplification required at a particular moment in order to maintain a predetermined lowest signal/noise ratio in the intended receiver. Hereby an automatic power control of the amplification can be achieved, whereby the use of energy is minimized. Furthermore, the control unit can change frequency of the received signal and transmit the received signal at another frequency or, when the received signal is spread spectrum signal, using another code. The entire antenna unit 101 is supplied with power via a power supply unit 117 connected to the mains. In a preferred embodiment the antenna unit is however provided with an internal power supply unit such as a battery or the like. This is possible since the antenna unit as described above makes use of significantly less energy than a corresponding conventional device such as a conventional repeater. Typically, the use of energy is reduced by about four times at the same signal/noise ratio (SNR) . I Fig. 2, a view in perspective of the antenna unit in Fig. 1 is shown. In the figure, the two patch antennas 107 and 109, respectively are shown located back to back on different sides of an amplifier module 102 implemented in multi-chip-module- technique or as an ASIC. The amplifier module 102 thus comprises the entire antenna unit 101 with exceptions from the antennas 107 and 109. Since the antennas are located back to back having the amplifier module located therein between and isolation between the antennas and at the same time the radiation fields from the antennas is directed in essentially the opposite directions . In Fig. 3, a more detailed block diagram of an implementation of an antenna unit as described above in conjunction with Fig. 1 and Fig. 2 is shown. The circuit in Fig. 3 comprises a first antenna 301, preferably a patch antenna, connected to a bandpass filter 303, which in turn is connected to a circulator 305. The circulator 305 is a three-way port used for directed signal transmission. Thus, an amplified signal, which is transmitted from a chip mounted power amplifier 307 is fed to the antenna 301 and a received signal is fed to a receiver circuit. Received signals are thus fed from the circulator 305 to an attenuation circuit 309 and further to a band-pass filter 311 via an amplifier 310 (Low Noise Amplifier LNA) . From the filter 311 the signal is fed to a mixer 313, which mixes the signal to the mid-frequency band. The mixer 313 is fed from a variable oscillator 315 provided to generate both half duplex and full duplex. The oscillator 315 is controlled by a phase-lock circuit 317 and the frequency is programmable via a serial port. The signal is fed from the mixer 313 to a SAW-filter 319 which is a mid-frequency filter having steep flanks . The output signal from the filter 319 is fed to a modulator/demodulator circuit 321 where the signal is demodulated and forwarded to a spread spectrum circuit 323 where the signal is recovered to a base-band signal. The base-band signal which is output from the circuit 323 is fed to a baseband circuit 325, which transmits digital data, measures the signal at the respective antennas and provides a connection to a control bus . The signal is then retransmitted via the second antenna 327 via a spread??? spectrum circuit 329, a modulator/demodulator circuit 331, a SAW filter 333, a mixer 335, a band-pass filter 337, a power amplifier 339, a circulator 341 and a band-pass filter 343. Reception and re-transmission of signals received by the second antenna 327 is performed in the corresponding way. In Fig. 4 an example of use of the antenna unit as described herein is shown. In the example in Fig. 4 an antenna unit as describes herein is mounted in an access network for broadband services, in particular an Internet connection. In Fig. 4 a base station 401 comprising a parabolic antenna 403 mounted in a tower 405, an antenna unit 407, as describes above in conjunction with Fig. 1 - 3 and an Yagi antenna 409 are shown. Further, a centrally located transmitter 411 and a client 413 are shown. The base station 401 acts as a relay station and retransmits signals from a centrally located transmitter and can comprise a large number of antenna units connected to a respective Yagi antenna each in order to cover an entire area of buildings etc. Thus, a signal is received from a centrally located transmitter using the parabolic antenna 403, which is directed towards one of the patch antennas on the antenna unit 407, wherein the signal is amplified and retransmitted via the second patch antenna on the antenna unit 407. The amplified signal is then transmitted to the Yagi antenna 409 using capacitive coupling, and which is directed towards the client which receive the signal, for example using a Yagi antenna 415. The use of a system as shown in Fig. 4 provides a robust access network for different data and telephony services at a low cost. By means of locating the antenna directly on the integrated circuit in the antenna unit as described herein, lines between the antenna and the amplifier are avoided, which in turn significantly reduce the attenuation which takes place in conventional repeaters and the like. This in turn result in that the antenna unit can be made smaller since the heat generation will be significantly reduced. Further, the device can be provided with an internal power supply source, resulting in that entire antenna unit can be made mobile. In order to obtain additional directivity in the radiation pattern from the antennas these can be arrange in so called strip lines .

Claims: CLAIMS 1. An antenna unit comprising at least a first and a second directional antenna and an amplifier provided to amplify a signal received by the first directional antenna and retransmit the signal via the second directional antenna, the antennas being formed directly on an integrated circuit, which integrated circuit also comprises the amplifier, characterized i that the first and second antenna are located back to back on different sides of the integrated circuit. 2. A unit according to claim 1, characterized in that the antennas are patch antennas . 3. A unit according to claim 1, characterized in that the antennas are formed by strip lines . 4. A unit according to any of claims 1 - 3, characterized in that the unit is supplied with power from an internal power supply source . 5. A unit according to any of claims 1 - 3, characterized in that the integrated circuit is implemented using a multi chip module technique or as an ASIC. 6. A unit according to any of claims 1 - 5, characterized in that the signal which is received via the first antenna is retransmitted at another frequency via the second antenna. 7. A relay station provided to amplify signals transmitted from a central transmitter to a receiver, characterized by an antenna unit comprising at least a first and a second directional antenna and an amplifier provided to ampl-ify a signal received by the first directional antenna and retransmit the signal via the second directional antenna, the antennas being formed directly on an integrated circuit which also comprises the amplifier and the first and second antenna being located back to back on different sides of the integrated circuit. 8. A relay station according to claim 7, characterized by a parabolic antenna provided to receive signals from the central transmitter and direct the received signal towards the first directional antenna of the antenna unit . 9. A relay station according to claim 7 or 8 , characterized by a Yagi antenna provided to receive signals from the second directional antenna of the antenna unit and direct the signal towards a receiver of the signal.

Inventors: OLESEN LYKKE, OLESEN, LYKKE
Applicants: OLESEN LYKKE, REPEAT IT AB, OLESEN, LYKKE
Application year: 2000
Main classification: H04B1
IPC codes: H01Q1, H01Q9, H01Q23