JP4522019B2 - Digital TV broadcast receiver and antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a receiver suitable for receiving terrestrial digital broadcasting, for example.
Terrestrial digital television broadcasts will become the mainstream of future television broadcasts because they have higher frequency utilization efficiency than conventional analog broadcasts, and therefore, high-quality and multi-channel broadcasts are possible.
[0002]
The present invention provides such a receiver for digital television broadcasting, particularly a receiver suitable for in-vehicle use, in particular its antenna. , Its antenna system, and diversity system Is described.
[0003]
[Prior art]
Terrestrial digital broadcasting can be hierarchically transmitted with different optimum transmission parameters for fixed reception (64QAM), mobile reception (16QAM or DQPSK), and portable reception (DPQSK).
As a result, high-definition television and multi-channel broadcasting are possible with a fixed receiver such as a general house, and mobile communication with a transmission capacity of up to about 10 Mbps is possible with an in-vehicle or portable receiver.
[0004]
By the way, in the above mobile communication,
(I) Since the ground clearance of the antenna is low, sufficient antenna gain cannot be obtained.
(Ii) The multipath fading received when moving in urban areas is quite remarkable.
(Iii) Doppler shift accompanying high-speed movement is inevitable.
For this reason, image disturbance called block noise occurs on the television screen. Block noise is black strip-like streaks appearing along a scanning line on a television screen, and is caused by image signals being compressed and transmitted in units of blocks.
[0005]
Through various tests, the present applicant, among the above (i), (ii) and (iii), (i) is an improvement of the antenna itself, (ii) is an improvement of the antenna and the diversity part, and ( In iii), it has been found that the generation of the block noise can be suppressed by improving the demodulator of the receiver.
[0006]
[Problems to be solved by the invention]
The present invention aims to put mobile reception into practical use, particularly focusing on (ii) among the above (i), (ii), and (iii), that is, aiming at improving multipath fading resistance. To do.
That is, an object is to realize mobile reception in which the generation of the block noise is suppressed as much as possible.
[0007]
[Means for Solving the Problems]
FIG. 1 is a diagram showing a basic configuration of the present invention.
In this figure, a digital television broadcast receiver 10 performs at least a pair of antennas 11 and 11 '(only one pair is shown in the figure) and predetermined processing (described later) on each input signal from these antennas 11 and 11'. And a frequency band division diversity controller 12 that receives the added signal.
[0008]
More specifically, the receiver 10 includes at least a pair of antennas 11 and 11 ′ and a frequency band division type diversity control unit 12 connected to the output side of the pair of antennas 11 and 11 ′. Here, each of the pair of antennas 11 and 11 ′ is a digital television set that is substantially non-directional with respect to directivity and has high polarization discrimination that can sufficiently distinguish both polarizations with respect to cross polarization discrimination. Broadcast receiver. Such a digital television receiver 10 can dramatically improve the video reception rate and sufficiently suppress the block noise described above.
[0009]
The reason for this configuration is due to theoretical and experimental considerations. This will be described below.
Conventional analog television signals are concentrated in the vicinity of the main carrier. On the other hand, a digital television signal is a signal modulated by an OFDM (Orthogonal Frequency Division Multiplex) method, and its power is almost uniformly distributed over a wide band.
[0010]
For this reason, in a receiver for digital television broadcasting, the conventional antenna switching diversity system for analog television cannot be adopted. This is because the power received by the pair of diversity antennas is always almost equal, and therefore, an antenna switching trigger cannot be obtained.
Therefore, it is assumed that multipath fading resistance is enhanced using a spatial diversity antenna structure that uses a pair of antennas. However, since the same switching as that used for analog television cannot be performed, in the present invention, After performing demodulation (DEMOD) processing described later, a predetermined reception frequency band (5.7 MHz) is divided into a plurality of small frequency bands, and one of the two antennas is divided for each of the divided small frequency bands. It is assumed that a frequency band division type diversity method of selecting is adopted. This is the frequency band division diversity controller 12 shown in FIG.
[0011]
It is understood that the multiband fading performance of a digital television broadcast receiver can be enhanced by such a frequency band division type diversity system (the theory will be described in detail later with reference to the drawings).
However, the adoption of the frequency band division type diversity system alone is not sufficient as a receiver for mobile communication intended by the present invention. This is because, for example, in-vehicle digital television receivers are particularly strongly affected by multipath fading because they move at high speed on ordinary roads and highways while passing through urban areas. Therefore, the present applicant mounted various types of antennas on a real vehicle and actually performed field tests using experimental radio waves. The experimental results are as follows.
[0012]
FIG. 2 is a diagram showing a video reception rate by an experiment in the frequency band division type diversity system.
In the left column of the figure, three types of antennas used in the test, that is, a glass antenna, a pole antenna, and a cross dipole antenna are shown. The glass antenna is an antenna developed by the present applicant, and is an antenna specialized for the UHF LOW band, which is a terrestrial digital television band. This glass antenna greatly improves reception sensitivity.
[0013]
On the other hand, the upper column of the figure is divided into two modes: when diversity is not functioning (OFF) and when it is functioning (ON). Note that the receiver input level in this test is −60 dBm at the pole antenna.
As shown in the figure, in any type of antenna, the video reception rate is significantly improved in the diversity ON mode.
[0014]
From this result, it was confirmed that the frequency band division type diversity scheme is extremely effective for multipath fading.
By the way, when the characteristics of the glass antenna, the pole antenna, and the cross dipole antenna in FIG. 2 under the diversity ON mode are analyzed, it is found that a somewhat unique phenomenon is observed.
[0015]
This peculiar phenomenon is that the above-mentioned pole antenna, which has a relatively low reception sensitivity as compared with a glass antenna, has a better video reception rate, such as 75.0%: 85.0%. ,That's what it means. That is, a high reception sensitivity (antenna gain) and a high video reception rate, that is, an improvement in anti-multipath fading performance are not related.
[0016]
In order to further investigate the above, a second experiment was conducted. This is an experiment for comparing antenna characteristics.
FIG. 3 is a diagram showing experimental results of antenna characteristic comparison.
The left column in this figure is exactly the same as the left column in FIG. On the other hand, the upper column of the figure shows each item of antenna characteristics, the right end of the upper column is an item related to directivity, and the center of the upper column is an item related to cross polarization identification. The left end of the upper column is exactly the same as the diversity ON item in FIG. 2 (video reception rate).
[0017]
What should be noted in FIG. 3 is that the following results (i) and (ii) were obtained.
(I) First, the better the cross polarization discrimination becomes (see the downward arrow <1> in FIG. 3), the better the video reception rate in the frequency band division diversity,
(Ii) In addition, the better the directivity (see the downward arrow <2> in FIG. 3), that is, the closer the antenna approaches omnidirectionality, the better the video reception rate.
[0018]
As a result, as schematically shown in FIG. 1, the receiver 10 of the present invention includes a pair of antennas 11 and 11 ′ that are non-directional and highly polarized, and a frequency band division diversity controller 12. Is an important component. However, even if omnidirectionality and high polarization discrimination are not necessarily satisfied at the same time, that is, only one characteristic of omnidirectionality and high polarization discrimination is satisfied, it is an object of the present invention. The anti-multipath fading performance can be improved to some extent.
[0019]
However, the best results are guaranteed when the above two characteristics are satisfied simultaneously.
Ideally, the above-described two characteristics should be satisfied at the same time in the above-described glass antenna that can ensure both good reception sensitivity and good appearance (appearance).
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 4 is a diagram showing an example of the overall configuration of a receiver to which the present invention can be applied. Throughout the drawings, the same components are denoted by the same reference numerals or symbols.
In FIG. 4, the pair of antennas 11 and 11 ′ and the frequency band division diversity controller 12 (shown as a demodulator 24) shown in FIG. 1 are positioned in the illustrated portion.
[0021]
The RF reception input from the pair of antennas 11 and 11 'is first converted into IF signals by the RF / IF converters 21 and 21', and these IF signals are digitally converted by the A / D converters 22 and 22 '. After being converted into the IF signal, the demodulation section 24 performs general demodulation. Here, frequency band division type diversity particularly related to the present invention is also performed, which will be described in detail later.
[0022]
The received signal from the demodulating unit 24 is separated from the multiplexed signal by the demultiplexing unit 25 and further decoded by the MPEG decoding unit 26. Thereafter, the instantaneous interruption processing unit 27 performs temporary processing so as not to make the image extremely worse when the radio wave is interrupted, and applies the received signal to the digital television monitor 29 via the video / audio output unit 28. To do.
[0023]
Thus, the receiver 10 based on the frequency band division type diversity scheme can be realized. Here, the frequency band division type diversity control unit 12 corresponding to the antennas 11 and 11 'and the demodulation unit 24 will be described in more detail.
FIG. 5A is a diagram schematically illustrating the characteristics of a pair of omnidirectional antennas, and FIG. 5B is a diagram schematically illustrating the characteristics of a pair of unidirectional antennas.
[0024]
In this figure, (a) represents the antenna directivity characteristics of a pair of omnidirectional antennas 11 and 11 'employed in the present invention, and (b) represents a pair of unidirectional antennas 15 and 15 that are not suitable for the present invention. It represents the antenna directivity of ′.
In the case of (b), the complementary effect in which the left / right antennas 15 and 15 'complement each other is small. Also, the Doppler frequency related to mobile communication differs and causes a synchronization shift.
[0025]
On the other hand, in the case of (a), the above-mentioned complementary effect is large.
(A) of FIG. 6 is a diagram schematically illustrating the individuality of an antenna having good cross polarization discrimination, and (b) of the antenna having poor cross polarization discrimination.
In the case of (b) in the figure, the antenna 16 (16 ′) is a low polarization discriminating antenna and receives H (horizontal) polarization and V (vertical) polarization without discrimination. .
[0026]
On the other hand, in the case of (a) adopted in the present invention, the antenna 11 (11 ′) is a highly polarized wave discriminating antenna, and receives only one of the polarized waves (H polarized wave in the figure), The other polarization (V polarization in the figure) is not received (indicated by X in the figure).
In the aspect (a), since the number of multipaths to be received is reduced, the diversity processing accuracy is increased, and therefore, the probability of complementation between a pair of antennas is increased. That is, the above-mentioned supplementary effect is increased.
[0027]
On the other hand, in the case of the mode shown in FIG. 7B, the number of multipaths to be received increases because the reverse of the case of the above-described mode of (a), and the diversity processing accuracy decreases, and therefore, the pair of antennas (16 , 16 ') The probability of complementation between each other is low. That is, the above-mentioned supplementary effect is small.
After all, it is effective to use omnidirectional antennas 11 and 11 '.
[0028]
Here, the received wave RF shown in FIGS. 5 and 6 will be described in more detail.
FIG. 7 is a diagram showing a spectrum of an RF reception wave. However, one mode of multipath fading is shown as an example.
In this figure, the left spectrum is for the antenna 11 on the left side (left side in the vehicle traveling direction in the case of in-vehicle use) of the pair of antennas 11 and 11 ′, and the right spectrum is the right antenna 11. It is about ′.
[0029]
According to this figure, a dip D (L) is generated on the low band side of the reception band of the antenna (left) 11, while the dip D (( R). Note that L represents Left (left) and R represents Right (right).
Then, the dip D (L) received by the antenna (left) 11 can be complemented by the antenna (right) 11 ', and the dip D (R) received by the antenna (right) 11' It can be supplemented by the antenna (left) 11.
[0030]
The spectrum shown in FIG. 7 is a spectrum of an RF reception wave modulated by the OFDM method. In the present invention, the control unit 12 shown in FIG. 1 performs frequency band division type diversity control on the RF reception wave. This is shown in FIG.
FIG. 8 is a diagram illustrating the principle of frequency band division type diversity control.
The left column of this figure shows a part of the spectrum of FIG. 7 and schematically shows it, and the center column performs S / N comparison for each of the extracted spectra A and B, and the S / N is always good. The right side (B1, A1, B2 in the figure) is selected, and the right column indicates the state where the selected A or B is sequentially arranged on the frequency axis. Thus, diversity control is executed. The hardware is executed by the circuit shown in FIG.
[0031]
FIG. 9 is a diagram illustrating an example of a circuit that executes frequency band division type diversity control.
In this figure, 11, 11 ', 21, 21', 22 and 22 'are as described in FIG. Further, the outline of the frequency band division type diversity control unit 12 (FIG. 1) forming a part of the demodulating unit 24 of FIG. 4 has already been described, but FIG. 9 shows a detailed example of the control unit 12 in particular. It is.
[0032]
The control unit 12 has FFTs 31 and 31 ′ in the first stage for converting outputs (time domain signals) from the A / D conversion units 22 and 22 ′ into frequency domain signals, respectively. That is, the main carrier shown in FIG. 7 is developed into a group of a plurality of subcarriers divided into small frequency bands.
Each data carried by these subcarriers is subjected to error correction processing in the demodulating units (DEMOD) 32 and 32 ', and the data of either one of the systems (11 or 11') is selected by the selecting unit 33. And applied to the subsequent stage, for example, the demultiplexing unit 25 of FIG.
[0033]
Selection at this time is performed by diversity control. That is, the S / N comparison unit 34 in FIG. 9 compares the signals from the FFTs 31 and 31 'individually with respect to the S / N, and the signal with the better S / N indicates which system (11 or 11'). ) To the selection unit 33. The selection unit 33 performs the above selection according to this instruction.
The basic configuration of the present invention has been described above, and the actual specific configuration will be described below particularly with respect to the antenna.
[0034]
The important point is that the antennas 11 and 11 'have a form equivalent to a crossed dipole antenna with respect to omnidirectionality and high polarization discrimination. The reason can be obtained from the experimental result of FIG. The expression “equivalent to a cross dipole antenna” is because the cross dipole antenna itself is not necessarily required. For example, the glass antenna shown in FIG. 3 only needs to have omnidirectionality and high polarization discrimination equivalent to a cross dipole antenna. Rather, if this glass antenna is used, it is further superior in terms of reception sensitivity and appearance.
[0035]
However, at present, the simplest method of realization is to construct the pair of antennas 11 and 11 'by the cross dipole antenna itself.
FIG. 10 is a diagram illustrating an example of a vehicle on which a pair of cross dipole antennas are mounted.
In this figure, a pair of cross dipole antennas 11 and 11 'are attached to the left and right of the rear part of the vehicle. In this case, it is desirable to attach it about 30 cm away from the surface of the trunk (or roof) at the rear of the vehicle. This is to prevent the gain of horizontal polarization from deteriorating. Thereby, the cross polarization discrimination with respect to the horizontal polarization becomes good, and the directivity in the horizontal plane is also desired.
[0036]
FIG. 11A is a plan view of a cross dipole antenna, and FIG. 11B is an equivalent circuit diagram thereof.
In the figure, A and A ′ are a pair of antenna elements, and B and B ′ are a pair of antenna elements orthogonal to the antenna elements.
The equivalent circuit of (b) shows that the cross dipole antenna is composed of baluns 41, 42 and 43 and a 90 ° phase shifter 44. As the 90 ° phase shifter 44, for example, a λ / 4 cable can be used.
[0037]
If the general dipole antenna itself shown in FIG. 11A is used, the appearance of the vehicle will deteriorate. Moreover, since the antenna element protrudes to the side of the vehicle, it cannot be said that it is preferable from the viewpoint of safety for passers-by. Therefore, for example, an antenna as shown in FIG. 12 is used.
FIG. 12 is a diagram showing a first embodiment of an antenna according to the present invention.
[0038]
According to the first embodiment of the present figure, the first antenna element pair 51, 51 'constituting the cross dipole antenna 11 (11') and the second antenna element pair 52, 52 'orthogonal thereto are arranged as a whole as a boomerang. Shape.
In this case, in order to obtain a boomerang shape, the first and second antenna elements 51 ′ and 52 ′ need to be sufficiently shorter than the first and second antenna elements 51 and 52, respectively. An example for this is shown in FIG.
[0039]
FIG. 13 is a diagram showing a first example of the antenna element pair of FIG.
According to the first example of this figure, the first antenna element 51 ′ (52 ′ is the same) is the helical antenna 54. Thereby, the element length of one of the first antenna elements 51 ′ (52 ′ is the same) is sufficiently shorter than the other 51 of the first antenna elements (the same is 52). By using the helical antenna, the physical length of the antenna element 51 '(52') can be made sufficiently shorter than the physical length λ / 4 of the antenna element 51 (52).
[0040]
Eventually, using the configuration of FIG. 13, each adjacent piece (51 ′, 52 ′) of the first antenna element pair 51, 51 ′ and the second antenna element pair 52, 52 ′ is removed by the helical antenna 54. Assume that the receiver is configured. It has been confirmed that the introduction of the helical antenna 54 does not lose the aforementioned omnidirectionality.
[0041]
14A and 14B are views showing a second embodiment of the antenna according to the present invention, in which FIG. 14A is a perspective view thereof and FIG. 14B is an equivalent circuit diagram thereof.
The second embodiment of this figure corresponds to the antenna elements 51 'and 52' of the first embodiment (FIG. 12) made extremely short, and the width of the boomerang can be further reduced.
[0042]
That is, with the vertical support pole 60 of the cross dipole antenna as the ground, the first pair of pieces (51, 52) and the first antenna element pair 51, 51 'and the second antenna element pair 52, 52' adjacent to each other and The length of each one of the second pair of pairs (51 ′, 52 ′) (51 ′, 52 ′ in FIG. 12) is made substantially zero (see (a) of FIG. 14).
[0043]
The equivalent circuit is as shown in FIG. The 90 ° phase shifter 41 and the balun 43 are the same as those shown in FIG.
In the second embodiment, when the ground (D) is arranged as shown in FIG. 14A, the antenna element 51 appears equivalent to a position symmetrical to D (forms 51 ′), and the antenna element 52 It utilizes the fact that it looks equivalent to a position symmetrical to D (forms 52 ').
[0044]
15A and 15B show a third embodiment of the antenna according to the present invention, in which FIG. 15A is a perspective view, FIG. 15B is a plan view, and FIG. 15C is an equivalent circuit diagram.
In the third embodiment of FIGS. 4A and 4B, a first antenna element pair is formed by a short antenna element 61 ′ and a long antenna element 61 extending in the same direction through a gap 63. The second antenna element pair is configured by the short antenna element 62 ′ and the long antenna element 62 extending in the same direction via the gap 64. Further, the vertical support poles 65 and 66 extending from one end of the short antenna elements 61 'and 62' on the opposite side to the gaps 63 and 64 are arranged in parallel and close to each other. On the other hand, the two long pieces of antenna elements 61 and 62 are arranged so as to be orthogonal to each other.
[0045]
The antenna elements 61, 61 ', 62, 62', the gaps 63, 64, and the vertical support poles 64, 65 are preferably integrally plastic molded as a whole.
Finally, an embodiment that positively realizes the above-described high polarization discrimination will be described.
FIG. 16 is a diagram showing a fourth embodiment based on the present invention which is particularly effective for realizing high polarization discrimination.
[0046]
In the fourth embodiment, a polarization diversity control function is further introduced into the receiver 10 in order to obtain the high polarization discrimination described above.
In FIG. 16, if a pair of antennas 11 and 11 'is an H polarization system, 111 and 111' are a pair of antennas of a V polarization system.
RF / IF, A / D, and FFT, which are constituent elements of the H polarization system, are exactly the same as those shown in FIG. 9, and the V polarization system is also configured.
[0047]
The S / N comparison unit 134 is functionally identical to the S / N comparison unit 34 in FIG. 9, and the selection unit 133 is also functionally identical to the selection unit 34 in FIG. 9.
On the other hand, the polarization intensity comparison unit 100 is unique to the fourth embodiment and compares which of the H polarization and the V polarization is being received strongly. A polarization selection unit 233 is provided in cooperation with the comparison unit 100, and a reception signal of the H polarization system or the V polarization system is selected according to the comparison result of the comparison unit 100.
[0048]
In summary, in the fourth embodiment, at least the pair of antennas described above includes a pair of horizontally polarized antennas 11 and 11 'and a pair of vertically polarized antennas 111 and 111', and a frequency band. The split type diversity control unit 12 is further provided with a polarization diversity control function (100, 233).
That is, if the comparison unit 100 detects that the polarization intensity is the highest, for example, in the H polarization system, the switch of the selection unit 233 is switched to the H polarization system. On the other hand, as described with reference to FIG. 9 independently for each of the H and V polarization systems, S / N comparison is performed, and one of the pair of antennas is selected.
[0049]
In addition, when knowing the traveling area of the vehicle and knowing in advance which polarization system (H / V) the broadcast there is, the designation of H or V is performed manually from the outside (EXT). You can also.
Further, considering a pair of H-polarization antennas (11, 11 ') and a pair of V-polarization antennas (111, 111'), as these antenna structures, a vertical support pole is used as a V-polarization antenna pole. It is preferable to use as both. This is to reduce the space occupied by the antenna.
[0050]
In summary, each of the pair of horizontally polarized antennas 11 and 11 'is constituted by a cross dipole antenna, and each of the pair of vertically polarized antennas 111 and 111' is a vertical support pole ( It is desirable to use a vertical pole antenna that also serves as 60) in FIG.
FIG. 17 is a diagram illustrating another example of a vehicle on which a pair of cross dipole antennas are mounted.
[0051]
As shown in FIG. 17, the long antenna elements O <b> 1 to O <b> 4 in the cross dipole antenna are disposed so as to extend in the vehicle inner direction and the vehicle rear, respectively.
By arranging in this way, the antenna element can be arranged without protruding from the side surface of the vehicle, so that the antenna element touches an obstacle on the side of the vehicle and is damaged. It can be prevented from being damaged.
[0052]
In addition, the antenna element extends not to the front but to the back (the element support extends in front of the element and from there to the rear), improving the stability of the antenna element against wind during running and driving at high speed This also prevents the antenna from being damaged and reduces wind noise.
[0053]
【The invention's effect】
As described above, according to the present invention, for example, a receiver that is optimal for terrestrial digital television broadcasting, particularly a receiver that is optimal for mobile communication such as in-vehicle use can be obtained. That is, it is possible to obtain a receiver that has excellent multipath fading resistance and can sufficiently suppress the occurrence of block noise on the television screen.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic configuration of the present invention.
FIG. 2 is a diagram showing a video reception rate by an experiment in a frequency band division type diversity system.
FIG. 3 is a diagram showing experimental results of antenna characteristic comparison.
FIG. 4 is a diagram illustrating an example of the overall configuration of a receiver to which the present invention can be applied.
5A is a diagram schematically illustrating the characteristics of a pair of omnidirectional antennas, and FIG. 5B is a diagram schematically illustrating the characteristics of a pair of unidirectional antennas.
FIGS. 6A and 6B are diagrams schematically illustrating the individuality of an antenna having good cross-polarization discrimination, and FIG. 6B being an illustration of antennas having poor cross-polarization discrimination.
FIG. 7 is a diagram showing a spectrum of an RF received wave.
FIG. 8 is a diagram illustrating the principle of frequency band division type diversity control.
FIG. 9 is a diagram illustrating a circuit example for performing frequency band division type diversity control;
FIG. 10 is a diagram showing an example of a vehicle on which a pair of cross dipole antennas are mounted.
11A is a plan view of a cross dipole antenna, and FIG. 11B is an equivalent circuit diagram thereof.
FIG. 12 shows a first embodiment of an antenna according to the present invention.
13 is a diagram showing a first example of the antenna element pair in FIG. 12. FIG.
FIG. 14 shows a second embodiment of an antenna according to the present invention.
FIG. 15 is a third embodiment of an antenna according to the present invention, where (a) is a perspective view, (b) is a plan view, and (c) is an equivalent circuit diagram.
FIG. 16 is a diagram showing a fourth embodiment based on the present invention, which is particularly effective for realizing high polarization discrimination.
FIG. 17 is a diagram showing another example of a vehicle on which a pair of cross dipole antennas are mounted.
[Explanation of symbols]
10. Digital TV broadcast receiver
11, 11 '... a pair of antennas
12. Frequency band division type diversity controller
21 ... RF / IF converter
22 ... A / D converter
24. Demodulator
29 ... TV monitor
31, 31 '... FFT
32, 32 '... demodulator (DEMOD)
33 ... Selection part
34 ... S / N comparison part
41, 42, 43 ... Balun
44 ... 90 ° phase shifter
51, 51 '... first antenna element pair
52, 52 '... second antenna element pair
54 ... Helical antenna
60 ... Vertical support pole
61, 62 ... long antenna element
61, 62 '... Short antenna element
63, 64 ... Gap
65, 66 ... Vertical support pole

Claims (14)

A pair of antennas for horizontal polarization and a pair of antennas for vertical polarization ;
It is connected to the output side of each of said pair of antenna, frequency subband diversity control for selecting one of a pair of antennas for one or the vertically polarized wave of the pair of antennas for the horizontally polarized wave in each divided frequency band And
Each of the said one pair of antennas here,
A receiver for digital television broadcasting, characterized by being substantially omnidirectional with respect to directivity and having high polarization discrimination capable of sufficiently discriminating both polarizations with respect to cross polarization discrimination. 2. The receiver according to claim 1, wherein each of the pair of antennas has a form exhibiting characteristics equivalent to a crossed dipole antenna with respect to the omnidirectionality and the high polarization discrimination. Each of the pair of antennas for horizontal polarization is constituted by a cross dipole antenna,
The receiver according to claim 1, characterized in that each of the pair of antennas for the vertically polarized waves, constitutes a vertical dipole antenna that also serves as a vertical support poles of the cross dipole antenna. Each of the pair of antennas for horizontal polarization and the pair of antennas for vertical polarization is constituted by a cross dipole antenna including a first antenna element pair and a second antenna element pair orthogonal thereto. The receiver according to claim 1 . The first antenna element pair constituting each of the pair of antennas having a form exhibiting characteristics equivalent to the cross dipole antenna and the second antenna element pair orthogonal thereto are formed into a boomerang shape as a whole. Item 3. The receiver according to Item 2. The receiver according to each piece adjacent each other of said first antenna element pair and the second antenna element pairs, to claim 4 or 5, characterized in that it constitutes a helical antenna. Each of the pair of antennas having a form exhibiting a characteristic equivalent to the cross dipole antenna has a vertical support pole as a ground, and a first piece of the first antenna element pair and the second antenna element pair adjacent to each other. the receiver of claim 4 or 5, characterized in that a substantially zero one length of the pair of pairs and a second piece. The short antenna element and the long antenna element extending in the same direction through a gap constitute the first antenna element pair,
The second antenna element pair is constituted by a short antenna element and a long antenna element extending in the same direction through a gap,
Furthermore, each vertical support pole extending from one end of each antenna element of each said short piece opposite to each said gap is arranged in parallel and close to each other,
Meanwhile, the antenna element of the two of the long piece receiver according to claim 4 or 5, characterized in that arranged orthogonal to each other. Each of the pair of antennas having a form exhibiting characteristics equivalent to the cross dipole antenna is mounted on a vehicle,
One of the antenna element of the long piece extending inwardly of the vehicle, the other receiver of claim 8, wherein the extending rearwardly of the vehicle. It is a cross-dipole antenna for frequency band division type diversity mounted on a vehicle,
With the vertical support pole of the cross dipole antenna as the ground, the length of one of the first piece pair and the second piece pair adjacent to each other of the first antenna element pair and the second antenna element pair is An antenna characterized by almost zero. It is a cross-dipole antenna for frequency band division type diversity mounted on a vehicle,
The short antenna element and the long antenna element extending in the same direction through a gap constitute the first antenna element pair,
The second antenna element pair is constituted by a short antenna element and a long antenna element extending in the same direction through a gap,
Furthermore, each vertical support pole extending from one end of each antenna element of each said short piece opposite to each said gap is arranged in parallel and close to each other,
On the other hand, the two antenna elements are arranged so as to be orthogonal to each other. The receiver of claim 11 one of the antenna elements of the long piece extending inwardly of the vehicle, the other, characterized in that extending rearwardly of the vehicle. An antenna system for a digital television broadcast receiver having a frequency band division type diversity controller,
It consists of a pair of antennas for horizontal polarization and a pair of antennas for vertical polarization ,
Each of the pair of antennas is substantially omnidirectional with respect to directivity, has high polarization discrimination that can sufficiently distinguish both polarizations with respect to cross polarization discrimination, and the frequency band division type diversity control. The unit selects one of the pair of horizontally polarized antennas or one of the pair of vertically polarized antennas for each divided frequency band. A frequency band division diversity system for a receiver for digital television broadcasting,
A pair of antennas for horizontal polarization and a pair of antennas for vertical polarization ;
It is connected to the output side of each of said pair of antenna, frequency subband diversity control for selecting one of a pair of antennas for one or the vertically polarized wave of the pair of antennas for the horizontally polarized wave in each divided frequency band And having a part
Each of the pair of antennas is substantially omnidirectional with respect to directivity, and has a high polarization discriminating property capable of sufficiently distinguishing both polarizations with respect to cross polarization discrimination. Diversity system.

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