JP2007235717A - Glass antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass antenna capable of obtaining excellent reception sensitivity over wide bands. <P>SOLUTION: The glass antenna comprises a power feeding point 28 formed in the vicinity of the edge of rear glass 20, an approximately rectangular loop-shaped conductor element 30 of which a surrounding length is L, and a linear conductor element 32 of which one terminal is connected to the power feeding point and another terminal is connected to the approximately rectangular loop-shaped conductor element, wherein the approximately rectangular loop-shaped conductor element 30 comprises a discontinuous portion 36 at a position of distance L/2 along with a loop from a connecting point where the linear conductor element is connected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a glass antenna formed on the surface of a vehicle glass plate, and more particularly to a glass antenna for TV broadcast waves.

  Patent Document 1 discloses a receiving antenna mainly for VHF-High band (170 to 224 MHz) for TV broadcast waves.

  FIG. 1 shows the pattern of this antenna. The shape and dimensions of the antenna pattern are described in paragraphs 0051 and 0055 of Patent Document 1.

  As shown in FIG. 1, the antenna includes a conductor element 12 extending in the lateral direction from the feeding point 10, a conductor element 14 extending in the vertical direction, and a loop-shaped conductor element 16 connected to the conductor element 14. .

When the wavelength λ _M of the center frequency (197 MHz) of the VHF-High band (170 to 224 MHz) and the wavelength shortening rate η are 0.65, the value of ¼λ _M · η is 247 mm, which is the vertical direction shown in FIG. It substantially corresponds to 255 mm, which is the sum of the dimension (30 mm) of the conductor element 14, the longitudinal dimension (30 mm) of the loop-shaped conductor element 16, and the lateral dimension (195 mm) of the loop-shaped conductor element 16.
Japanese Patent Application No. 2005-101809

  The antenna disclosed in Patent Document 1 is mainly used for the VHF-High band, but it is necessary to provide a conductor element 12 extending laterally from the feeding point 10 in order to increase the sensitivity of the UHF band (470 to 770 MHz). was there.

  An object of the present invention is to provide a glass antenna capable of obtaining good reception sensitivity in a wide band (for example, VHF-High and UHF bands) without providing an element extending in a lateral direction from a feeding point.

  The present invention provides a glass antenna formed on the surface of a vehicle rear glass, a feeding point formed in the vicinity of an edge of the rear glass, a substantially rectangular loop-shaped conductor element having a peripheral length L, and one end of the conductor antenna A linear conductor element connected to a feeding point and having the other end connected to a substantially rectangular loop-shaped conductor element, the substantially rectangular loop-shaped conductor element from a connection point to which the linear conductor element is connected A discontinuous portion is provided at a distance L / 2 along the loop.

The distance from the feeding point to the discontinuous portion is a distance along the linear conductor element and the substantially rectangular loop conductor element, and is ¼λ _L · η (λ _L is a reception wavelength of the received radio wave. The band is preferably a wavelength band longer than the center wavelength, and η is a wavelength shortening rate due to glass).

In addition, an auxiliary conductor element connected to the linear conductor element and extending in a direction substantially perpendicular to the linear conductor element, the end of the auxiliary conductor element not connected to the linear conductor element from the feeding point Is a distance along the linear conductor element and the auxiliary conductor element, and ¼λ _H · η (λ _H is a wavelength shorter than the center wavelength in the reception wavelength band of the received radio wave, η Is preferably a wavelength shortening rate due to glass.

Here, when the glass antenna is a glass antenna that can obtain good reception sensitivity in the VHF-High band (170 to 224 MHz) and the UHF band (470 to 770 MHz), λ _H is a wavelength at a frequency of 470 to 770 MHz. 0.39 to 0.64 m. λ _L is a wavelength at a frequency of 170 to 470 MHz and is 0.64 to 1.76 m. Therefore, when the wavelength shortening rate η is 0.65, ¼λ _H η is 63 to 104 mm, and ¼λ _L η is 104 to 286 mm.

  According to the glass antenna of the present invention, good reception sensitivity can be obtained over a wide band.

  FIG. 2 shows an embodiment of the glass antenna of the present invention. This glass antenna is provided on the rear glass 20 of the vehicle and in a space between the uppermost hot wire 22 of the defogger and the vehicle body. A body located at the top of the rear glass is indicated by 24, and a body located at the side of the rear glass is indicated by 26.

  This glass antenna has a feeding point 28 formed in the vicinity of the edge of the rear glass 20, a conductor element 30 having a substantially rectangular loop shape with a peripheral length L, one end connected to the feeding point 28, and the other end And a linear conductor element 32 connected to a substantially rectangular loop conductor element 30.

  The substantially rectangular loop-shaped conductor element 30 is provided with a discontinuous portion 36 at a distance L / 2 along the loop from a connection point 34 where the element 30 and the linear conductor element 32 are connected. The non-continuous part is a gap (GAP) and the width is 5 mm. That is, the conductor element 30 does not form a completely closed loop, but is cut at a discontinuous portion.

The distance from the feeding point 28 to the discontinuous portion 36 is a distance along the linear conductor element 32 and the substantially rectangular loop conductor element 30, and is ¼λ _L · η (λ _L is in the reception wavelength band of the received radio wave. The wavelength band is longer than the central wavelength, and η is preferably a wavelength shortening rate due to glass.

  Since the discontinuous portion (GAP) 36 exists in the substantially rectangular loop conductor element 30 in the antenna pattern of the present embodiment, good reception sensitivity can be obtained over a wide band. The evaluation results in actual measurement are shown below.

  FIG. 3 shows the reception sensitivity measured for a glass antenna without a discontinuous portion and a glass antenna with a discontinuous portion. The VHF-Low band (1 to 3 ch), VHF-High band (4 to 12 ch), and UHF band (13 to 64 ch) of the broadcast wave were measured separately. In the figure, a solid line graph indicates a case where there is a discontinuous portion, and a broken line graph indicates a case where there is no discontinuous portion.

  According to the actual measurement result, no sensitivity difference is observed in the VHF band (91 MHz to 224 MHz) depending on the presence or absence of the discontinuous portion, but the improvement in sensitivity is 3 dB at maximum in the UHF band higher than 600 MHz. That is, it can be seen that an antenna provided with a discontinuous point in a substantially rectangular loop conductor element has improved UHF band sensitivity while maintaining reception sensitivity in the VHF band, and is an antenna that functions in a wider band. This is because when the discontinuous portion 36 is not provided in the substantially rectangular loop-shaped conductor element 30, the high-frequency current propagating from the upper side portion of the conductor element 30 and the high-frequency current propagating from the lower side portion interfere with each other, and the conductor element Although a stable standing wave is not generated on 30, the discontinuous portion 30 is provided in the conductor element 30, thereby eliminating interference of each high-frequency current propagating from the upper side and the lower side. It is presumed that this is an effect that the standing wave due to the resonance of 4λ · η is stably present on the conductor element.

  Furthermore, in the antenna pattern of this example, the sensitivity difference due to the difference in distance from the body was examined.

  In FIG. 2, the distance from the metal plate 26 of the non-continuous portion 36 is A, the dimensions (unit: mm) of each conductor element are set as shown in the figure, and the dimensions of A are changed to obtain VHF-High (175-175). 295 MHz) and UHF (475 to 790 MHz) bands, the reception performance with respect to horizontal polarization was measured.

  FIG. 4 shows the measurement results of the operating gain when the distance A is 10 mm, 20 mm, 40 mm, 60 mm, 80 mm, and 100 mm, respectively. Table 1 shows the average value of the reception performance (operation gain).

  From the above measurement results, when the dimension A is narrower than 20 mm, the band sensitivity of VHF-High is lowered, but no sensitivity difference is recognized in a region beyond that (40 mm to 100 mm). It can also be seen that the sensitivity of UHF is stably maintained at a high level (-10 dB or more).

  Further, in the antenna pattern of this example, the influence of the distance B from the defogger was examined. FIG. 5 shows the interval B.

  The distance A was fixed at 80, and the interval B was changed for analysis. FIG. 6 shows the measurement results of the reception performance (operation gain) when the interval B is 10 mm, 20 mm, 40 mm, and 60 mm, respectively. Table 2 shows the average value of the operating gain.

  From the above measurement results, performance fluctuation due to narrowing the interval B is observed in the VHF-Low band of 70 MHz to 150 MHz due to the influence of the defogger, but in the target band (170 MHz or more), the sensitivity due to the proximity of the defogger No change is allowed.

  Furthermore, in the antenna pattern of this example, the sensitivity variation due to the shape of the substantially rectangular loop-shaped conductor element was evaluated. The antenna pattern of FIG. 7 shows the height dimension E of the substantially rectangular loop-shaped conductor element to be changed.

  FIG. 8 shows the measurement results of the operating gain when the distance A is fixed to 80 mm, the interval B is fixed to 60 mm, and the dimension E is 5 mm, 10 mm, 20 mm, 40 mm, 50 mm, and 70 mm, respectively. Table 3 shows the average value of the operating gain.

  From the above measurement results, it can be seen that even if the height dimension is arbitrarily set (5 to 70 mm) in the VHF band and the UHF band, the reception characteristics are hardly affected.

FIG. 9 shows an antenna pattern of still another embodiment of the glass antenna of the present invention. These are provided with auxiliary conductor elements in order to increase the sensitivity of the UHF band as in the prior art.
FIG. 9A shows an example in which one lateral auxiliary conductor element 40 is added.
FIG. 9B shows an example in which two lateral auxiliary conductor elements 42 and 44 having the same length are added.
FIG. 9C shows an example in which two lateral auxiliary conductor elements 46 and 48 having different lengths are added.
FIG. 9D shows an example in which a loop-shaped lateral auxiliary conductor element 50 is added.
FIG. 9E shows an example in which one vertical auxiliary conductor element 52 is provided and power is supplied from the side.

  An example of the glass antenna shown in FIG. 9A is shown in FIG. The length of the auxiliary conductor element 40 is 80 mm. A distance between the auxiliary conductor element 40 and the feeding point 28 is defined as D, and patterns with distances D of 0 mm, 20 mm, and 30 mm are considered.

  The reception sensitivity was measured for the glass antenna with the discontinuous portion shown in FIG. For comparison, the reception sensitivity was also measured for a glass antenna having the same pattern and having no discontinuous portion.

  Table 4 shows the VHF reception sensitivity of the glass antenna without the discontinuous part, and Table 5 shows the VHF reception sensitivity of the glass antenna with the discontinuous part.

  In Tables 4 and 5, numerical values in parentheses are sensitivity differences with respect to reception sensitivity for glass antennas without auxiliary conductor elements. For reference, the reception sensitivity of the glass antenna without the auxiliary conductor element is also shown in the table.

  As can be seen from the measurement results shown in Tables 4 and 5, there is no change in sensitivity due to the auxiliary conductor element 40 in the VHF band. That is, even if the auxiliary conductor element is provided, the sensitivity is not affected in the VHF band.

  Table 6 shows the UHF-Low reception sensitivity of a glass antenna without a discontinuous part, and Table 7 shows the UHF-Low reception sensitivity of a glass antenna with a discontinuous part.

  In Tables 6 and 7, numerical values in parentheses are sensitivity differences with respect to reception sensitivity for glass antennas without auxiliary conductor elements. For reference, the reception sensitivity of the glass antenna without the auxiliary conductor element is also shown in the table.

  Table 8 shows the UHF-High reception sensitivity of a glass antenna without a discontinuous part, and Table 9 shows the UHF-High reception sensitivity of a glass antenna with a discontinuous part.

  In Tables 8 and 9, the values in parentheses are sensitivity differences with respect to reception sensitivity for glass antennas without auxiliary conductor elements. For reference, the reception sensitivity of the glass antenna without the auxiliary conductor element is also shown in the table.

  As can be seen from the measurement results shown in Tables 6 to 9, in the UHF band, when D = 0 mm, the sensitivity is lowered in the low band (UHF-Low). This is because the antenna has a resonance point at a high frequency due to the addition of the auxiliary conductor element. When the D value is increased to 20 mm, 30 mm, and 40 mm, the length from the feeding point 28 to the auxiliary conductor element 40 is increased, and the sensitivity reduction in the low frequency band can be corrected.

  In the UHF-High band, it can be seen that the reception sensitivity is increased by providing the auxiliary conductor element.

  In the glass antenna having the pattern of FIG. 10, the reception sensitivity was measured for D = 20 mm and 40 mm. For comparison, the reception sensitivity is measured for a glass antenna from which the auxiliary conductor element is removed from the pattern of FIG. Asked.

  FIG. 11 shows a sensitivity difference in the case of the VHF band, and FIG. 12 shows a graph of the sensitivity difference in the case of the UHF band.

  As shown in the graph of FIG. 12, when D = 20 mm, the sensitivity is improved in the band of 530 MHz to 770 MHz, and in the case of D = 40 mm, the band of 512 MHz to 758 MHz is obtained. Thus, the auxiliary conductor element has an effect of improving the reception performance in the UHF band.

  As is clear from FIG. 11, in the VHF band, there is no sensitivity fluctuation due to the addition of the auxiliary conductor element, and the good reception performance shown in FIG. 3 is maintained.

  From this, it is clear that the glass antenna further provided with the auxiliary conductor element can perform VHF to UHF broadband reception.

  From the above analysis results, the following can be understood.

  (1) If the distance A to the body is 20 mm or more, the distance A from the defogger is not affected by the approach of the heat ray and has stable performance. As a result, it is expected that the antenna can be designed even for a vehicle type with a narrow antenna design area.

  (2) If the height E of the substantially rectangular loop-shaped conductor element is 5 to 70 mm, there is no change in performance, but in consideration of securing an area for adding an auxiliary conductor element that contributes to improving the performance of the UHF band, It is preferable to set it as about 5-60 mm.

  (3) The reception performance obtained with the glass antenna of the present invention maintains a stable performance of about −10 dB in the VHF-High band (150 MHz to 290 MHz), and UHF has an auxiliary conductor in addition to its own performance. Since adjustment by the element is possible, stable performance in a wide band can be obtained.

  Since the glass antenna of the present invention has a compact and simple shape, it can be used as an antenna for IC tag reception / transmission in addition to the vehicle window glass antenna.

It is a figure which shows the pattern of the conventional antenna. It is a figure which shows one Example of the glass antenna of this invention. It is a figure which shows the receiving sensitivity measured about the glass antenna without a discontinuous part, and the glass antenna with a discontinuous part. It is a figure which shows the measurement result of the operation gain at the time of changing the distance A. It is a figure which shows an antenna pattern. It is a figure which shows the measurement result of the operation gain when the space | interval B is changed. It is a figure which shows an antenna pattern. It is a figure which shows the measurement result of the operation gain when the dimension E is changed. It is a figure which shows the pattern of the glass antenna of this invention which provided the auxiliary conductor element. It is a figure which shows the pattern of the glass antenna which provided the auxiliary conductor element. It is a graph which shows the sensitivity difference in the VHF band by the presence or absence of a discontinuous part in the glass antenna of FIG. It is a graph which shows the sensitivity difference in the UHF band by the presence or absence of a discontinuous part in the glass antenna of FIG.

Explanation of symbols

20 Rear glass 22 Defogger hot wire 24, 26 Body 28 Feeding point 30 Substantially rectangular loop conductor element 32 Linear conductor element 36 Non-continuous portion

Claims (3)

In the glass antenna formed on the surface of the vehicle rear glass,
A feeding point formed near the edge of the rear glass;
A substantially rectangular loop-shaped conductor element having a circumferential length L;
A linear conductor element having one end connected to the feeding point and the other end connected to a substantially rectangular loop-shaped conductor element;
The glass antenna, wherein the substantially rectangular loop-shaped conductor element is provided with a discontinuous portion at a distance L / 2 along the loop from a connection point where the linear conductor element is connected. The distance from the feeding point to the discontinuous portion is a distance along the linear conductor element and the substantially rectangular loop conductor element, and is ¼λ _L · η (λ _L is a reception wavelength band of a received radio wave). The glass antenna according to claim 1, wherein the glass antenna has a wavelength band longer than the center wavelength, and η is a wavelength shortening rate due to glass. One or more auxiliary conductor elements are connected to the linear conductor element and extend in a direction substantially perpendicular to the linear conductor element, and the linear conductor element of the auxiliary conductor element is not connected from the feeding point The distance to the end is the distance along the linear conductor element and the auxiliary conductor element, and 1 / 4λ _H · η (λ _H is a wavelength band shorter than the center wavelength in the reception wavelength band of the received radio wave. The glass antenna according to claim 1, wherein η is a wavelength shortening rate due to glass.

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