KR20070068756A - Antenna system for satellite digital multimedia broadcasting - Google Patents

Abstract

An antenna system for satellite DMB(Digital Multimedia Broadcasting) is provided to receive both circular polarization signal and linear polarization signal from a satellite through one antenna, thereby increasing user's convenience as anticipating miniaturization of the antenna. A planar antenna(100) performs a role of radiating signals, and operates by a load of an active element. Active modules(110,120) use the planar antenna(100) as an output matching factor, and change load impedance through DC(Direct Current) bias to determine physical size by changing a resonance frequency according to a physical valid wavelength of the planar antenna(100). Output modules(210,220) control input impedance of the planar antenna(100) and output of the active modules(110,120). A coupling module(300) conducts power distribution and phase shift for feedback signals inputted to generate linear polarization/circular polarization characteristics of the planar antenna(100), and delivers the results to the output modules(210,220). A switching module(400) switches to determine on/off actions of the active modules(110,120). A control module(500) controls the switching action of the switching module(400), so that the circular polarization/linear polarization characteristics of the planar antenna(100) are determined.

Description

Antenna system for satellite digital multimedia broadcasting {ANTENNA SYSTEM FOR SATELLITE DIGITAL MULTIMEDIA BROADCASTING}

1 illustrates a configuration of a front-end stage of an antenna system for satellite digital multimedia broadcasting applied to an embodiment of the present invention.

 2 is a block diagram illustrating a configuration of an antenna system for satellite digital multimedia broadcasting according to an embodiment of the present invention.

3 is a circuit diagram showing an internal circuit of the antenna system for satellite digital multimedia broadcasting according to an embodiment of the present invention.

The present invention relates to an antenna system and method for satellite digital multimedia broadcasting, and more particularly, to an antenna system and method for satellite digital multimedia broadcasting that can use satellite DMB service through an active antenna that can accommodate both circular and linear polarized signals. It is about.

In general, Digital Multimedia Broadcasting (DMB) is a mobile multimedia broadcasting service capable of providing high quality voice and video services anytime, anywhere, and is based on digital audio broadcasting (DAB) commercially available in Europe and the United States. The broadcast adds video, weather, news and data information.

Such DMB broadcasting will be divided into satellite DMB and terrestrial DMB, and the satellite DMB will be clearly displayed through mobile phones, car receivers, small TVs, PDAs, etc., even in vehicles running at 150km / h using approximately 2.6GHz band. It is a mobile broadcasting service of God concept that can see.

As such, the broadcast can be viewed through a mobile phone, which is a representative convergence service of broadcasting and communication. When a radio wave is launched from a broadcasting center to a satellite, the broadcast is transmitted directly from the satellite to the terminal.

In this case, in the shadow area of the city, broadcasts can be received through a terrestrial repeater called a "Gap Filler". Because of the use of satellites, broadcasts of clear image quality can be seen anywhere in the country.

On the other hand, in the service of digital multimedia (DMB) TV broadcasting by satellite, it is impossible to receive in the shaded area where the radio waves are weak, so a terrestrial repeater (gap filler) is required. After receiving the signal, the signal is re-amplified to the same frequency and re-copyed to the service antenna.

When the DMB satellite receives a broadcast signal of about 13 GHz from the DMB center on the ground, the DMB satellite transmits a signal of about 12 GHz for the terrestrial repeater and a signal of about 2.6 GHz for direct reception by the terminal. At this time, the terrestrial repeater is a system for transmitting a signal for a terminal in an area where satellite signals cannot reach, and is installed in an urban area where a multipath fading phenomenon occurs mainly. Send by signal.

Satellite DMB antennas are largely classified into a satellite signal receiving antenna for receiving a circularly polarized signal directly from a satellite and a repeater signal receiving antenna for receiving a linear polarized signal from a terrestrial repeater.

In shaded areas such as underground or buildings ("Non Line-of-sight") where direct signal reception is not possible with satellites, the antenna for repeater signal reception in the shaded area receives satellite signals and In the case of good areas, a relatively large satellite reception antenna is separately mounted to receive signals directly from the satellite.

The satellite signal is a time division multiplexing (TDM) type S-band (2㎓-3㎓) signal and can be received by circular polarization of Right Hand Circular Polarization (RHCP). The repeater signal must carry a small antenna as an S-band signal in the form of linearly polarized code division multiplexing (CDM).

As described above, the satellite DMB service using the satellite DMB antenna according to the related art has a problem in that an antenna for receiving a CDM linear polarization signal received from a repeater and a TDM circular polarization signal directly received from a satellite is required separately.

In addition, the antenna for receiving the circularly polarized signal has a relatively large physical size compared to the antenna for receiving the linearly polarized signal, which makes it difficult to be embedded in a mobile communication terminal, thereby causing inconvenience to the user due to poor portability. There is this.

Therefore, there is an urgent need to develop an antenna for satellite DMB capable of receiving signals from a satellite using one antenna regardless of the polarization signal without separately using an antenna for receiving a circularly polarized signal and a linearly polarized signal.

The technical problem to be achieved by the present invention is to accommodate both the circular polarization signal and the linear polarization signal from the satellite through one antenna to increase the user convenience, and antenna system for satellite digital multimedia broadcasting that can expect the miniaturization of the antenna To provide.

According to an aspect of the present invention, there is provided an antenna system for satellite digital multimedia broadcasting, comprising: a planar antenna serving as a radiator and operating as a load of an active element; An active module which uses the planar antenna as an output matching element and determines a physical size by changing a load impedance through a DC bias to change a resonance frequency with respect to a physical effective wavelength of the planar antenna; An output module for adjusting the output of the active module and the input impedance of the planar antenna; A coupling module for power distribution and phase shifting the feed signal input to generate linear polarization / circular polarization characteristics of the planar antenna, and transferring the result to the output module; A switching module for switching to determine an on / off operation of the active module; And a control module for controlling the circular polarization / linear polarization characteristics of the planar antenna by controlling the switching operation of the switch module.

The planar antenna is a microstrip antenna, which can be designed in the form of a rectangular, circular, elliptical, triangular, annular-ring.

Preferably, the coupling module evenly distributes the power input from the input terminal to increase the bandwidth, and outputs two equal output signals having a phase difference of 90 degrees through the first and second output terminals.

The active module and the output module are connected to a first output terminal of the coupling module, and a first output module and a first active module are installed on a first line connected to the planar antenna, and a second output of the coupling module is provided. A second output module and a second active module are installed in a second line connected to the terminal and connected to the planar antenna.

In this case, the first output module includes a first transformer, a first capacitor, a first radial stub, and the first active module includes a first transistor, and the second output module includes a second transformer and a second transistor. And a capacitor, a second radial stub, and the second active module includes a second transistor.

The first radial stub and the second radial stub serve to separate the RF circuit portion in which the transformer and the capacitor are disposed from the DC bias circuit portion in which the transistor is disposed.

The control module causes the switching module to turn on both the first transistor and the second transistor so that the planar antenna supports circular polarization characteristics, and the switching module causes the switching module to support the linear polarization characteristics. Only one of the first transistor and the second transistor is turned on.

The active module is designed to design the planar antenna through a difference between an oscillator and an amplifier, an input and an output impedance to amplify a signal received from the planar antenna so as to adjust a direction of a radiation pattern of the planar antenna by adjusting an oscillation frequency. And at least one of the buffers to reduce noise.

The output module adjusts a bias for applying current / voltage of collectors / drains of the first and second transistors and an external matching circuit for adjusting an input impedance of the planar antenna, and the matching circuit controls noise of a corresponding operating frequency range. Implemented in the form of a low pass filter / high pass filter to remove a.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

First, a configuration of an antenna system for satellite digital multimedia broadcasting applied to an embodiment of the present invention will be described with reference to FIG. 1.

1 illustrates a configuration of a front-end stage of an antenna system for satellite digital multimedia broadcasting applied to an embodiment of the present invention.

Referring to FIG. 1, the front-end of the antenna system for satellite digital multimedia broadcasting includes an antenna 10 for receiving a digital multimedia broadcasting frequency signal and a transmission line for transmitting the signal received from the antenna 10 to the LNA 30 ( 20).

At this time, the low noise amplifier (LNA) 30 is called a low noise amplifier, and receives the DMB frequency signal from the weak antenna 10 and amplifies it.

Next, an antenna system for satellite digital multimedia broadcasting according to an embodiment of the present invention will be described in detail with reference to FIGS. 2 and 3.

2 is a block diagram showing the configuration of an antenna system for satellite digital multimedia broadcasting according to an embodiment of the present invention, and FIG. 3 is a circuit diagram showing an internal circuit of the antenna system for satellite digital multimedia broadcasting according to an embodiment of the present invention.

As shown in Figures 2 and 3, the antenna system for satellite digital multimedia broadcasting according to the embodiment of the present invention, the planar antenna 100, the first and second active modules (110, 120), the first and second outputs Modules 210 and 220 include, but are not limited to, coupling module 300, switching module 400, and control module 500.

The planar antenna 100 is a microstrip antenna that functions as a radiator and operates as a load of the active modules 110 and 120.

The planar antenna 100 may be designed and changed in the form of various squares such as rhombus or rectangle, circular, elliptical, triangular, annular-ring.

The active modules 110 and 120 use a planar antenna as a matching element of the output modules 210 and 220, and change a resonant frequency with respect to the physical effective wavelength of the planar antenna by changing a load impedance through a DC bias. To determine the physical size.

At this time, the active module 110, 120 is a design is concentrated on the input impedance side rather than the output impedance is relatively easy to design, and may use an oscillator that can adjust the direction of the radiation pattern of the antenna by adjusting the oscillation frequency, planar antenna An amplifier may be used to amplify the signal received at 100 and a buffer may be used to reduce the design and noise of the planar antenna through the difference between the input and output impedances.

When the active modules 110 and 120 are designed as amplifiers, input / output impedance adjustment is difficult, and the input impedance of the antenna is included in the portion determining the output impedance of the active modules 110 and 120, thereby optimizing the input impedance of the antenna. Although it is difficult to design the amplifier through, it has been used most recently for the implementation of an active antenna.

Meanwhile, when the active modules 110 and 120 are designed as buffers, the input impedance may be reduced to be strong against external noise, and the output impedance may be adjusted so that the input impedance may be adjusted to 50 or 75 ohms, which is the antenna itself.

As such, the active modules 110 and 120 may selectively use an oscillator, an amplifier, and a buffer, and use the oscillator, the amplifier, and the buffer to be suitable for implementation and design in consideration of the above-described features.

The output module 210, 220 adjusts the bias, the external matching circuit, that is, the output portion of the active module 110, 120 and the input impedance of the planar antenna 100.

As shown in FIG. 3, the output modules 210 and 220 include transformers T1 and T2, capacitors C1 and C2, and radial stubs RS1 and RS2 as well as the planar antenna 100.

The output modules 210 and 220 are bias and external matching circuits that apply current / voltage of collectors / drains of the first and second transistors Q1 and Q2 that are the active modules 110 and 120, that is, the outputs of the active module. The part and the input impedance of the planar antenna 100 are adjusted, and the matching circuit is implemented in the form of a low pass filter / high pass filter to remove noise in the corresponding operating frequency range.

The coupling module 300 may be formed in a lattice form in order to increase the bandwidth, and evenly distributes the power input from the input terminals, and may provide two through the first and second output terminals output1 and output2. The even output signal is output with the phase difference of 90 degrees.

The coupling module 300 uses a hybrid coupler such as a 3 dB quadrature coupler or a branch line coupler, and directly couples through a branch line. Representative transmission line (Microstrip / stripline) coupler is used.

In this case, the coupling module 300 may generate a signal having a 90 degree difference in phase due to the same size in a desired operating frequency range by changing the length of L1 / L2.

In this case, L1 and L2 have a length of wavelength lambda / 4, and the length portion of L1 / L2 is such that the length of the wavelength varies depending on the operating frequency.

The switching module 400 performs a switching operation to determine the on / off operation of the first and second transistors Q1 and Q2 according to the switching control signal, and the transistor is provided at the base end of the first and second transistors Q1 and Q2. Inverter circuit using / FET is used.

The control module 500 generates a switching control signal and outputs the switching control signal to the switching module 400 so that the circular polarization / linear polarization characteristics of the planar antenna 100 are determined.

Referring to FIG. 3, the first and second active modules 110 and 120 and the first and second output modules 210 and 220 are connected to the first output terminal of the coupling module 300 and connected by a plane antenna. The first output module 210 and the first active module 110 is installed on the first line to be connected, and the second output is connected to the second output terminal of the coupling module 300 and connected to the second line connected to the planar antenna. The module 220 and the second active module 120 are installed.

The first output module 210 includes a first transformer T1, a first capacitor C1, a first radial stub RS1, and the first active module 110 includes a first transistor Q1. The second output module 220 includes a second transformer T2, a second capacitor C2, and a second radial stub RS2, and the second active module 120 supplies the second transistor Q2. Include.

In this case, the first radial stub RS1 and the second radial stub RS2 may include a portion of an RF circuit in which the first and second transformers T1 and T2 and the first and second capacitors C1 and C2 are disposed. The DC bias circuit portions in which the first and second transistors Q1 and Q2 are disposed are separated from each other.

The radial stubs RS1 and RS2 are patterns of transmission lines when the actual stubs RS1 and RS2 are implemented on a printed circuit board (PCB). The lengths of the stubs RS1 and RS2 are designed as wavelength / 4, and the matching circuit and the transistor Q1 of the output modules 210 and 220 are used. , Q2) to isolate the bias circuit from each other.

The radial stubs RS1 and RS2 separate DC bias circuits and RF circuits between input and output when the length of the transmission line corresponds to wavelength / 4 based on the transmission line theory of high frequency engineering. The bias voltage applied to the gate can be changed according to the specification of the transistor and the applied voltage, but preferably has a value designed according to the bias condition.

Next, the operation of the satellite digital multimedia broadcasting antenna system according to an embodiment of the present invention will be described in detail.

A switch may be added so that only a single phase signal is applied to the input signal applied to the coupling module 300 to support the linear polarization. However, in the embodiment of the present invention, the operation of the active module 110 or 120 may be determined. The switching module 400 is being added.

That is, the control module 500 disables any one of the first and second active modules 110 and 120 through the switching module 400 to support linear polarization, and to support circular polarization. Both the first and second active modules 110 and 120 are enabled through the switching module 400 to operate simultaneously.

In this case, the switching module 400 may turn on both the first transistor Q1 and the second transistor Q2 to change the axial ratio of the planar antenna 100 to adjust the appropriate circular polarization characteristics.

The switching module 400 is installed toward the output terminal of the coupling module 300 and serves to turn on / off the bias application of the base / gate of the active modules 110 and 120.

The planar antenna 100 may improve the performance by modifying the shape of the antenna in a circular, elliptical, or annular ring shape in terms of supporting circular polarization characteristics.

As described above, when the polarization characteristics of the planar antenna 100 are determined by the control module 500 and the switching module 400, the output modules 210 and 220 may output the output portions of the active modules 110 and 120 and the planar antenna 100. ), The input impedance is adjusted, and the matching circuit removes the noise in the corresponding operating frequency range.

By doing so, the antenna system for satellite digital multimedia broadcasting according to the embodiment of the present invention increases the diversity and efficiency in product design by reducing the effective size of the antenna required for the use frequency, and the linear polarized signal of the repeater and the satellite according to the needs of the user. Circular polarization signals received directly from the antenna can be simultaneously received by one antenna.

The drawings and detailed description of the invention are merely exemplary of the invention, which are used for the purpose of illustrating the invention only and are not intended to limit the scope of the invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the antenna system for satellite digital multimedia broadcasting according to the present invention implements an active antenna capable of receiving both linearly and circularly polarized signals, thereby reducing the effective size and physical size of the antenna and improving diversity and efficiency in product design. In addition, it is possible to receive all signals for satellite digital multimedia broadcasting regardless of polarization using one antenna, thereby improving user convenience and miniaturizing the antenna.

Claims (12)

A flat antenna serving as a radiator and operating as a load of an active element; An active module which uses the planar antenna as an output matching element and determines a physical size by changing a load impedance through a DC bias to change a resonance frequency with respect to a physical effective wavelength of the planar antenna; An output module for adjusting the output of the active module and the input impedance of the planar antenna; A coupling module for power distribution and phase shifting the feed signal input to generate linear polarization / circular polarization characteristics of the planar antenna, and transferring the result to the output module; A switching module for switching to determine an on / off operation of the active module; And Control module for determining the circular polarization / linear polarization characteristics of the planar antenna by controlling the switching operation of the switch module Satellite digital multimedia broadcasting antenna system comprising a. The method of claim 1, The planar antenna is a microstrip (Microstrip) antenna, the antenna system for satellite digital multimedia broadcasting, characterized in that it can be designed in the form of square, circular, oval, triangle, annular-ring (Annular-Ring). The method of claim 1, The coupling module evenly distributes the power input from the input terminals to increase the bandwidth, and distributes the two equal output signals 90 degrees out of phase through the first and second output terminals 1 and 2. Satellite system for digital multimedia broadcasting, characterized in that for outputting. The method of claim 3, The coupling module is a satellite digital multimedia broadcasting antenna system, characterized in that using a hybrid (Hybrid) coupler, such as a 3dB quadrature coupler or a branch line coupler. The method of claim 3, The active module and the output module are connected to the first output terminal of the coupling module, the first output module and the first active module is installed on a first line connected to the planar antenna, And a second output module and a second active module are installed on a second line connected to the second output terminal of the coupling module and connected to the planar antenna. The method of claim 5, The first output module includes a first transformer, a first capacitor, a first radial stub, and the first active module includes a first transistor. And the second output module includes a second transformer, a second capacitor, and a second radial stub, and the second active module includes a second transistor. The method of claim 6, The first radial stub and the second radial stub serve to separate the RF circuit portion in which the transformer and the capacitor are disposed and the DC bias circuit portion in which the transistor is disposed from each other. system. The method of claim 6, The control module causes the switching module to turn on both the first transistor and the second transistor so that the planar antenna supports circular polarization characteristics, and the switching module causes the switching antenna to support the linear polarization characteristics. An antenna system for satellite digital multimedia broadcasting, wherein only one of the first transistor and the second transistor is turned on. The method of claim 1, The active module is an antenna system for satellite digital multimedia broadcasting, characterized in that for using the oscillator to adjust the direction of the radiation pattern of the planar antenna by adjusting the oscillation frequency. The method of claim 1, The active module is an antenna system for satellite digital multimedia broadcasting, characterized in that for using the amplifier to amplify the signal received from the planar antenna. The method of claim 1, And the active module uses a buffer to reduce the design and noise of the planar antenna through the difference between input and output impedances. The method of claim 6, The output module adjusts a bias for applying current / voltage of collectors / drains of the first and second transistors and an external matching circuit for adjusting input impedance of the planar antenna, And the matching circuit is implemented in the form of a low pass filter / high pass filter to remove noise in a corresponding operating frequency range.

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