KR100310989B1 - Antenna system using low power amplifier - Google Patents

Abstract

PURPOSE: An antenna system using a low power amplifier is provided to prevent an unnecessary power consumption, and drastically reduce costs by controlling a direction of radiation of beams by using a multi-beam feed element. CONSTITUTION: A switch(21) selects a vertical direction of radiation. A super high frequency wave lens(22) feeds a phased array multi-beam. A plurality of low power amplifiers(23) amplify a signal. A transmitting antenna system is installed on a tower. A 3-bit electronic beam control signal(25) is transmitted from an operator's controller which is positioned on a remote place within a cell in a wireless manner, transmitted from a telephone, etc. in a wired manner, or transmitted from a base station where the operator is positioned in a wired or wireless manner. According to the electronic beam control signal(25), the switch(21) is operated. When a beam port is selected among eight beam ports, an input signal passes through the super high frequency lens(22) from the selected beam port, and distributed to the eight array ports. The signals distributed to the array ports are inputted to the eight low power amplifiers(23) while maintaining a predetermined phase difference.

Description

Antenna System Using Low Power Amplifier

The present invention relates to an antenna system that improves the performance of an antenna for use in wireless communication such as digital cellular, personal mobile communication, wireless data communication, frequency common communication, future land mobile communication, wireless subscriber network, and multi-point distribution service. .

The performance of an antenna system used in a base station is to transmit and receive the signal of the electric field strength necessary to the subscribers in the cell radius through the transmitting antenna, and to transmit and receive the signal of the electric field strength copied from the antenna of the subscriber station through the receiving antenna A series of service quality improvements and cost savings associated with the installation, maintenance, and control.

1A and 1B are exemplary views illustrating a configuration of a conventional base station antenna system, in which, "11" is a high power amplifier, "12, 15" is a high frequency cable, "13" is a transmitting antenna, "14" is a receiving antenna, and "16". "17" denotes a low noise amplifier, "17" denotes a transmission / reception antenna, and "18" denotes a bracket.

Looking at the configuration and operation of the conventional base station antenna system in detail as follows.

First, after amplifying a signal to be transmitted by the high power high power amplifier 11 located in the base station and transmitting the signal to the transmitting antenna 13 installed on the antenna tower on the roof through a high frequency cable 12 of about several tens of meters, the transmitting antenna ( 13 copies the transmitted signal into space.

On the other hand, the high frequency signal radiated from the antenna of the subscriber station and received by the receiving antenna 14 is transmitted to the low noise amplifier 16 for receiving indoors through the high frequency cable 15 which also reaches several tens of meters. The low noise amplifier 16 then amplifies the received weak signal into a signal of strength required at the base station.

In the conventional base station antenna system as described above, the high frequency cable 12, which is inevitably arranged to reach several tens of meters around the element element of the building in which the base station is located, is applied at about 1/2 (3 decibels) of transmission power in the case of transmission. This can cause unnecessary power consumption. Therefore, in order to maintain the required field strength for the subscribers within the cell radius, the base station should be provided with a higher output high power amplifier 11 in consideration of the loss on the high frequency cable 12. However, the higher the power output 11, the more expensive, the larger the size, the lower the efficiency. In addition, since unnecessary power consumption generates heat as the efficiency is low, the cooling fan must be driven for heat dissipation, which causes noise pollution.

As described above, the conventional base station antenna system causes excessive power consumption and increased cost, and the lifespan of the power amplifier is short as the system configuration is complicated, and has a fatal weakness of complete interruption of service in case of failure.

In the conventional base station antenna system as described above, the power loss by the high frequency cable 15 in the case of reception causes a decrease in reception sensitivity of 3 decibels or a depth signal to noise ratio. Therefore, a communication service provider requires a low noise amplifier of excessive specification (low noise figure, high power, etc.) in order to prevent a decrease in call quality due to a decrease in reception sensitivity or a decrease in a reception signal-to-noise ratio, thereby increasing the cost of the system.

On the other hand, when the electric field strength of the base station signal is high, the base station signal acts as an unnecessary interference signal to subscribers of the neighboring cells, causing a deterioration in the quality of service, thereby changing the radiation direction of the base transceiver station antenna. Is required.

Accordingly, the conventional base station transmit / receive antenna 17 uses a method of changing a radiation direction of the antenna by mechanically turning a graduated bracket 18 by climbing up a tower. However, this incurs additional maintenance costs, makes it difficult to replace quickly in case of bad weather such as snow and rain, resulting in deterioration of service quality, and also causes safety accidents.

Looking at the problems of the conventional base station antenna system collectively as follows.

First, a high-power amplifier located inside a base station amplifies the signal to a high power of about tens to hundreds of watts, and then transmits the signal to a transmitting antenna installed on a rooftop tower through a high frequency cable of about tens of meters, and the receiving antenna transmits the received high frequency signal. It is also transmitted to the receiving device of the base station room through a high frequency cable. High frequency cables usually use expensive low loss and high output cables to prevent signal attenuation, but in the case of mobile communication and wireless base station antenna systems, the length of wiring from indoors to rooftops is usually about tens of meters. A power consumption equal to 1/2 (3 decibels) is generated. As described above, the conventional base station antenna system consumes power unnecessarily in the case of transmission, and there is a problem in that the reception sensitivity is deteriorated due to the relative increase in noise in the case of reception.

Second, high power amplifiers are more expensive, more expensive, and less efficient. As the efficiency is low, unnecessary power consumption generates heat, so the cooling fan must be driven for heat dissipation, which causes noise pollution. Such a conventional base station antenna system causes a power consumption and an increase in cost, the lifespan of the power amplifier is short as the configuration of the system is complicated, there is a fatal problem of complete service failure in the event of a failure.

Third, in the conventional base station antenna system, a method is used in which a person climbs over a tower and mechanically returns an antenna. Such a conventional base station antenna system incurs additional maintenance costs, makes it difficult to replace quickly in case of bad weather such as snow and rain, resulting in a drop in service quality, and also includes a risk of a safety accident.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and by using a low-power amplifier of several watts, which is much weaker than a high-power amplifier used in a conventional antenna system, by raising the tower together with the antenna to drive in a phased arrangement, unnecessary power in a high frequency cable The purpose of the present invention is to provide a new type of antenna system that prevents consumption and significantly reduces the cost by controlling the beam's radiation direction by using a multi-beam feeding element such as a switch and a microwave lens according to a control signal from a remote location. have.

1A and 1B are exemplary views of a configuration of a conventional base station antenna system.

2 is a block diagram of an embodiment of a transmission antenna system using a low power amplifier according to the present invention;

3 is a block diagram of an embodiment of a receiving antenna system according to the present invention;

4 is a structural diagram of an embodiment of an ultra-high frequency lens according to the present invention;

5 is an illustration of simulation results for a beam steering radiation pattern in accordance with the present invention.

* Explanation of symbols for main parts of the drawings

21, 33: switch 22, 32: ultra-high frequency lens

23: low power amplifier 24, 31: array antenna

25, 34: electronic beam control signal 26: radiation beam

27: equiphase 35: low noise amplifier

In the antenna system of the present invention for achieving the above object, in the antenna system for copying the signal to be transmitted, a plurality of signals each having a predetermined phase difference according to the propagation path difference by receiving a signal through a predetermined beam port Phased array means for distributing a plurality of array ports; Switching means for switching a signal transmitted from the base station to the antenna side through a transmission line to a predetermined beam port of the phase arrangement means in accordance with a control signal for determining a radiation direction input from the outside; A plurality of low power amplification means for low power amplifying a plurality of signals correspondingly input from the plurality of array ports of the phase arrangement means; And a phased array copying means for copying a plurality of signals inputted from the plurality of low power amplifying means, wherein the plurality of copied signals are synthesized in equiphase to form a radiation beam in a predetermined direction.

In addition, another antenna system of the present invention is an antenna system for receiving a signal, comprising: phased array receiving means for receiving a signal copied from an antenna of a terminal according to a phase difference; A phase for synthesizing each signal at a predetermined beam port by receiving a plurality of received signals having a phase difference from the phased array receiving means to a plurality of array ports correspondingly and making phases of the respective signals in phase according to propagation path differences Arrangement means; Low noise amplification means for low noise amplifying the synthesized signals in equiphase and transmitting them to the base station through a transmission line; And switching means for switching the equiphase synthesized signal output from the predetermined beam port of the phase arrangement means to the low noise amplifying means in accordance with a control signal input from the outside.

In addition, another antenna system of the present invention, in the antenna system, for receiving a signal through a predetermined beam port for distributing a plurality of signals each having a predetermined phase difference according to the propagation path difference to a plurality of array ports One phase arrangement means; First switching means for switching a signal transmitted from the base station to the antenna side via a transmission line to a predetermined beam port of the first phase arrangement means in accordance with a control signal for determining a radiation direction input from the outside; A plurality of low power amplifying means for low power amplifying a plurality of signals correspondingly input from the plurality of array ports of the first phase arrangement means; A phased array copying means for copying a plurality of signals inputted from said plurality of low power amplifying means, wherein said plurality of copied signals are synthesized in equiphase to form a radiation beam in a predetermined direction; Phased array receiving means for receiving a signal copied from an antenna of the terminal according to a phase difference; Receiving a plurality of received signals having a phase difference from the phased array receiving means to a plurality of array ports correspondingly, and synthesizing each signal at a predetermined beam port by making phases of the respective signals equal in phase according to propagation path differences. Two phase arrangement means; Low noise amplifying means for low noise amplifying a signal synthesized in phase and transmitting the same to the base station through a transmission line; And second switching means for switching the equiphase synthesized signal output from the predetermined beam port of the second phase arrangement means to the low noise amplifying means in accordance with a control signal input from the outside.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a diagram illustrating an embodiment of a transmission antenna system using a low power amplifier according to the present invention, and illustrates an antenna system operating in a phased array method by feeding a microwave lens.

The transmission antenna system according to the present invention includes a switch 21 for vertical radiation direction selection, an ultra-high frequency lens 22 for phased array multibeam feeding, a plurality of low power amplifiers 23 and an array antenna 24 for amplifying a signal. It is mounted on top of the tower.

The operating principle of the transmission antenna system according to the present invention is a three-bit that has been wirelessly transmitted from a controller of an operator located in a remote place in a cell, transmitted by wire, such as a telephone, or transmitted by wire or wireless from a base station where an operator is located. When the switch 21 is operated according to the electronic beam control signal 25 and one of the eight beam ports b1 to b8 is selected, the input signal is inputted from the selected beam port b3 to the ultra high frequency lens ( Passed by 22 are distributed to eight array ports a1 to a8 respectively.

As such, the signals distributed to each array port in the lens are input to eight low power amplifiers 23 having a constant phase difference by the propagation path difference in the lens and are amplified at low power, and then are fed to the array antenna 24 and radiated into the air. do. At this time, the phase difference by the ultra-high frequency lens 22 is radiated from the array antenna 24 to form an isophase surface 27 (the same phase is the same) as the dotted line in the figure, and is perpendicular to the isophase surface 27. Spatially synthesized to form a radiation beam 26 having a constant downward angle from the horizontal plane.

At this time, the output of each of the low power amplifier 23 is synthesized in proportion to the number of arrays, and the radiation gain of the array antenna 24 is also increased in proportion to the number of arrays. Therefore, as shown in Equation 1 below, the final spatially synthesized effective radiation output ERP is arranged at the output P of the low power amplifier 23 and the radiation gain G of the array antenna 24. Incremented by (N) times the square.

[Equation 1]

ERP = PGN ²

Therefore, when the antenna system according to the present invention in which a plurality of low power amplifiers and array antennas are arranged in only a few watts is used in a base station such as mobile communication, personal mobile communication, and wireless communication, a single high output power amplifier of tens to hundreds of watts is provided. An effective radiation output equal to or greater than that of a conventional base station antenna system using a single high gain antenna can be obtained.

A closer look at this principle is as follows.

In a typical base station transmit antenna system, when the output of the base station high power amplifier is P ₁ , the loss of the feed cable is L, and the gain of the transmitting antenna is G ₁ , the effective radiation output is

ERP ₁ = P ₁ G ₁ L

= (P ₁ L) G ₁

In the case of the present invention, when the output of the low power amplifier is P ₂ , the antenna gain is G ₂ , and the number of arrays is N, as shown in Equation 1, the effective radiation output is

ERP ₂ = P ₂ G ₂ N ²

= (P ₂ N) (G ₂ N)

Becomes This means that the amplifier output and antenna gain are increased by N times by the active phased array effect.

In the above two effective radiation output equations, assuming that the antenna gains of both sides are equal to each other, since G ₁ = G ₂ N,

Should be

In other words, it means that a low-power amplifier can be used by dividing the loss of the feed cable from the output of the conventional high-power amplifier by the number of arrays.

For example, the output P ₁ = 20Watt = 43dBm of the existing high power amplifier, and the feed loss averages L If it is 4dB and array number N = 8

to be.

Therefore, instead of one 20-watt high-power amplifier, we substitute eight low-power amplifiers at the 1-watt level to obtain the same effective radiated output. Another benefit is that the output is lowered, improving efficiency from about 7% to 25%, reducing power requirements from about 286 Watts to 32 watts, reducing heat dissipation from 266 Watts to 24 Watts. The reduction and the reliability of the device are improved.

In the case of a receive antenna system, the noise figure of the receive antenna system rises by (NF _{1 dB} + L _dB ) since the loss L of the feed cable in the prior art is added to the noise figure NF ₁ of the low noise amplifier.

However, in the case of the present invention, since the feed cable is located behind the low noise amplifier, the noise figure of the receiving antenna system is NF _{2 dB} , and using the same low noise amplifier as in the prior art, the noise figure of the receiving antenna system is improved by the feed cable loss.

In addition, when the noise index of the receiving antenna system is the same as the conventional antenna system, the noise index specification of the amplifier, which is as low as the loss of the feed cable, can be relaxed, and the cost reduction effect can be obtained.

3 is a configuration diagram of an embodiment of a receiving antenna system according to the present invention. After synthesis, the configuration of an antenna system for amplifying a low power low noise amplifier is shown.

Looking at the operating principle of the receiving antenna system according to the present invention, there is a phase difference according to the direction of each high-frequency signal radiated from the antenna of the subscriber station received by the array antenna 31 from a specific direction.

Each received signal having a phase difference is input to the array ports a1 to a8 of the ultra-high frequency lens 32, and is equalized by the propagation path difference in the lens and synthesized at one beam port b3. On the other hand, the noise received together with the received signal is random in phase and is synthesized at any beam port of the ultra-high frequency lens 32 and thus eliminated.

Ultimately, the switch 33 according to the 3-bit electronic beam control signal 34 that has been wirelessly transmitted from an operator located at a remote location within a cell or transmitted by wire, such as a telephone, or has been transmitted by wire or wirelessly from a base station where the operator is located. ), And when any one of the eight beam ports b1 to b8 is selected, the received signal of the base station is inputted to the low-power low noise amplifier 35 and amplified by the received signal synthesized in the corresponding port, and then the receiver of the base station. Is passed to. Thus, since the received signal-to-noise ratio is improved at the beam port selected by the control signal 34, it is input to the low-power low noise amplifier 35, so that the call quality is improved.

4 is a structural diagram of an embodiment of an ultra-high frequency lens according to the present invention, which is an example of implementing an ultra-high frequency lens on a microstrip substrate by an etching method.

As shown in the figure, an ultra-high frequency lens implemented by using eight beam ports and an array port of the fourteen beam ports and the array ports on the left and right sides may be used in the antenna system shown in FIGS. 2 and 3. Each of the six remaining ports is reserved for future expansion. The eight beam ports and the array port in the center are designed to steer by dividing the ± 10 ° section into eight beams at approximately 2.8 ° intervals.

Since the ultra-high frequency lens is a passive element, there is no directivity, and thus the same principle may be applied to a transmission / reception antenna.

FIG. 5 is an exemplary diagram of a simulation result for the beam steering radiation pattern according to the present invention, and shows transmission and reception radiation patterns when selecting each beam port, and the horizontal axis represents angle and the vertical axis represents electric field intensity.

As described above, it can be seen that each main beam is steered in a section substantially divided into eight ± 10 ° sections.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.

The present invention as described above has the following effects as compared to the conventional base station antenna system.

First, the antenna system according to the present invention does not require the wiring of expensive high power amplifiers and high frequency cables of several tens of meters, compared to the conventional antenna system, it is possible to significantly reduce the cost of system installation and maintenance.

Second, the present invention using a low-power amplifier that can implement a small size, high efficiency, low cost and long life compared to the amplifier with a high output has the effect of greatly reducing the power consumption, according to the separate heat dissipation and cooling in addition to natural convection There is no need for a system, which saves money.

Third, in the case of a conventional antenna system using a single high-power amplifier, the failure and replacement of the high-power amplifier immediately leads to disconnection of the service, whereas the antenna system according to the present invention using a plurality of low-power amplifiers is a phased low-power amplifier Even if one of the failures occurs, the reduction of the overall radiated power is only 1 to 2 decibels, which can prevent a sudden deterioration in the quality of service and secure the time required for maintenance replacement.

Fourth, each of the beam ports of the ultra-high frequency lens is designed to correspond one-to-one with one transmission direction, so when the network management needs beam steering, for example, by dialing a base station and giving a remote control command to the switch, By simply changing the beam port of the ultra-high-frequency lens, the direction of radiation of the antenna beam can be immediately changed in the desired direction, and the effect of immediately re-measuring the field strength at the remote site to check whether the radiation beam has changed There is.

Fifth, since the present invention can remotely control the radiation beam, maintenance personnel can climb on the pylon to reduce the network maintenance costs required to mechanically turn the antenna, it is possible to prevent safety accidents.

Sixth, in the present invention, a signal received by each array antenna from a specific direction is synthesized at the corresponding beam port so that the signal is enhanced but the phase difference is random and is not synthesized. Therefore, since the received signal is amplified low noise after the signal-to-noise ratio is greatly improved, the call quality is greatly improved.

Claims (13)

An antenna system for copying a signal to be transmitted, comprising: phase arrangement means for receiving a signal through a predetermined beam port and distributing a plurality of signals each having a predetermined phase difference according to a propagation path difference to a plurality of array ports; Switching means for switching a signal transmitted from the base station to the antenna side through a transmission line to a predetermined beam port of the phase arrangement means in accordance with a control signal for determining a radiation direction input from the outside; A plurality of low power amplification means for low power amplifying a plurality of signals correspondingly input from the plurality of array ports of the phase arrangement means; And a phased array copying means for copying a plurality of signals inputted from said plurality of low power amplifying means, wherein said plurality of copied signals are synthesized in equiphase to form a radiation beam in a predetermined direction. The antenna system according to claim 1, wherein each means is provided on a tower side of the antenna. The antenna system according to claim 1 or 2, wherein said phase arrangement means comprises an ultra-high frequency lens for phased array multibeam feeding. The antenna system of claim 1 or 2, wherein the control signal for determining the radiation direction is transmitted from an operator located at a remote location in the cell. The antenna system according to claim 1 or 2, wherein the control signal for determining the radiation direction is transmitted from a base station where an operator is located. 3. The phased array copying means according to claim 1 or 2, characterized in that the phased array copying means has an effective radiant power as long as the output gain of the low power amplifying means and the radiation gain of the phased array copying product are multiplied by the square of the number of arrays. Antenna system. An antenna system for receiving a signal, comprising: phased array receiving means for receiving a signal copied from an antenna of a terminal according to a phase difference; A phase for synthesizing each signal at a predetermined beam port by receiving a plurality of received signals having a phase difference from the phased array receiving means to a plurality of array ports correspondingly and making phases of the respective signals in phase according to propagation path differences Arrangement means; Low noise amplification means for low noise amplifying the synthesized signals in equiphase and transmitting them to the base station through a transmission line; And switching means for switching the equiphase synthesized signal output from the predetermined beam port of the phase arrangement means to the low noise amplifying means in accordance with a control signal input from the outside. 8. The antenna system according to claim 7, wherein each of the means is provided on a tower side of the antenna. The antenna system according to claim 7 or 8, wherein the phase arrangement means comprises an ultra high frequency lens. The antenna system of claim 7 or 8, wherein the control signal is transmitted from an operator located at a remote location in the cell. The antenna system of claim 7 or 8, wherein the control signal is transmitted from a base station where an operator is located. An antenna system comprising: first phase arrangement means for receiving a signal through a predetermined beam port and distributing a plurality of signals each having a predetermined phase difference according to a propagation path difference to a plurality of array ports; First switching means for switching a signal transmitted from the base station to the antenna side via a transmission line to a predetermined beam port of the first phase arrangement means in accordance with a control signal for determining a radiation direction input from the outside; A plurality of low power amplifying means for low power amplifying a plurality of signals correspondingly input from the plurality of array ports of the first phase arrangement means; A phased array copying means for copying a plurality of signals inputted from said plurality of low power amplifying means, wherein said plurality of copied signals are synthesized in equiphase to form a radiation beam in a predetermined direction; Phased array receiving means for receiving a signal copied from an antenna of the terminal according to a phase difference; Receiving a plurality of received signals having a phase difference from the phased array receiving means to a plurality of array ports correspondingly, and synthesizing each signal at a predetermined beam port by making phases of the respective signals equal in phase according to propagation path differences. Two phase arrangement means; Low noise amplifying means for low noise amplifying the synthesized signals in equiphase and transmitting the same to the base station through a transmission line; And second switching means for switching the equiphase synthesized signal output from the predetermined beam port of the second phase arrangement means to the low noise amplifying means in accordance with a control signal input from the outside. The antenna system according to claim 12, wherein each means is provided on a tower side of the antenna.