CA1071753A - Multiband antenna for window panes - Google Patents

Multiband antenna for window panes

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Publication number
CA1071753A
CA1071753A CA257,851A CA257851A CA1071753A CA 1071753 A CA1071753 A CA 1071753A CA 257851 A CA257851 A CA 257851A CA 1071753 A CA1071753 A CA 1071753A
Authority
CA
Canada
Prior art keywords
legs
rim
pane
multiband antenna
antenna
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA257,851A
Other languages
French (fr)
Inventor
Mauro Comastri
Giorgio Ciarniello
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Societa Italiana Vetro SIV SpA
Original Assignee
Societa Italiana Vetro SIV SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Societa Italiana Vetro SIV SpA filed Critical Societa Italiana Vetro SIV SpA
Priority to CA257,851A priority Critical patent/CA1071753A/en
Application granted granted Critical
Publication of CA1071753A publication Critical patent/CA1071753A/en
Expired legal-status Critical Current

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Abstract

ABSTRACT OF THE DISCLOSURE
A car windshield antenna comprises a central fishpole-type portion and a portion extending at least partly around the rim of the windshield. The rim portion is formed of a conductor which extends horizontally away from its junction with the fishpole-type portion and then doubles back to form a loop. At the end of the loop the conductor extends vertically parallel to the fishpole-type portion until adjacent the end of the fishpole-type portion where it then extends horizontally along at least part of the rim.
The fishpole-type portion mainly picks up the metric wave band but it also participates in pick-up of the medium wave band and the rim portion mainly picks up the medium wave band but it also participates in pick-up of the metric band.

Description

1~71753 MULTIBAND ANTENNA FOR WTNDOW PANES

The present invention refers to a radio-receiving multiband antenna supported on window panes, particularly for a windshield of motor vehicles. The term "window pane"
is intended to mean in this connection a pane of glass or of plastic material and the antenna may consist of electric conductors deposited by the silk screen process on the pane, prefera~ly on that face of the pane which, when fitted into the car, is the internal one; or else, if in lieu of tempered glass, two bonded together glass panes are used, applied to that face of the pane, which is in contact with the other face. Obviously, in lieu of conductors made by the silk screen process, also a conducting metal wire may be used.
Obviously, such antenna may be applied ~o any ~indow of a motor vehicle, although the windshield is the most suitable place.
The antenna according to the present inven-tion has been designed to reGeive radio-frequency signals in their various bands of transmissions, such as long waves, medium waves, short waves, metric or frequency modulation waves tFM) and VHF, deci-metric waves and UHF and all the waves for sound - 1 .

7~753 and/or television information, included the frequencies reserved for radio amateurs.
The antenna incorporated in the pane, particu- ' larly in the windshield, is preferred to the conventional, freely supported motorcar antennas, because they are ; subjected to various drawbacks, such as:
a) considerable vibrations during driving which render the signal fluctuating, particularly when re-ceiving distant stations and the receiver operates in threshold conditions;
b) marked instability in their characteristics, such as increase of their resistance and consequent in-crease in their losses, changes in the capacity of the antenna, due to its aging, to the possibility of water ; penetration in the cylindric bottom element, which causes corrosion and oxidation of the tubular elements in a polluting or brackish atmosphere;
c) in the case of fishpole antennas, the fact that they strongly project beyond the motorcars contours, which leads often to their breaking, for instance when entering a garage, an underpass, etc., or damaging persons and goods if they are badly installed;
d) furthermore the fishpole antenna is also sub-ject to be willfully broken by vandals.

-~07~753 For all these reasons windshield antennas have been developed, It is well known that the major part of radio-receiving sets for motor vehicles is provided with a single aerial socket, differently from the domestic receivers which have an input for the medium waves and one for the metric waves (FM), therefore a problem which must be faced in the aerials embedded in motorcar wind-shields is that of obtaining good reception of the 10 medium waves as well as of the metric waves in a single antenna socket of the radio-receiving set.
In order to obtain a good reception, the ideal would be that of having an antenna of a length equal to a well defined fraction of the wave length to be re-ceived, such as ~/2 or ~/4 according to whether the antenna is of a symmetrical or assymetrical type.
The standard sizes of motor vehicle windshields render, at least for the medium wave range, antennas of such t length impossible.
; 20 The invention solves this problem by providing an antenna wherein the geometry of its conductors is such as to form two parts, the first one constituting the active element in the reception of medium waves ~ 3 ~

1~717S3 and the second part forming the active element for the reception of metric waves, but wherein that part of the antenna, which is not involved during the reception of one band, does not form a parasitic element during the reception of this band, but even contributes positively toward the reception of the whole signal. For this reason the whole, antenna, in lieu of acting like two distinct units, acts as a real multiband antenna.
According *o the present invention, there is provided a multiband antenna applied to a window pane, particularly a windshield, for reception of radio signals for a radio receiver having a single antenna input, the antenna comprising: a terminal for connection of the antenna to the receiver; and electrical conductor means connected to said terminal and extending in a generally vertical direction up to a distance a few centimeters from a first rim of said pane and branching off into two oppositely directed conductive legs, the oppositely directed legs extending parallel to said first rim and then turning respectively substantially 90 in opposite directions so as to define two further legs extending adjacent respective second and third rims of said pane, the free ends of said further legs being looped back to form respective additional legs running parallel to at least portions of said oppositely directed legs.
The invention will be better understood from the following description, made with reference to the attached drawing, wherein:
Figure 1 represents a conventional, two-conductor T-type antenna applied to a windshield;
Figure 2(a) and (b) show two versions of a first embodiment of the antenna according to the invention;
Figures 3(a) and (b) show a second embodiment of an antenna according to the invention, in two versions;
Figures 4(a) and (b) shows a third embodiment of the antenna ' ~, ~

1~7~753 ~:
according to the invention, in two versions;
Figures 5~a) and (b) show a fourth embodiment of the antenna according to the invention, in two versions. ` :-All embodiments are shown as applied to a windshield. All figures marked (a) show two-conductor versions;

. $, .

: :

-4a-~o7~753 .

all figures (b) show a single conductor version Of the respective embodiment. In all figures, the same elements have been indicated ~ith the same reference numerals.

.
The known antennas of figure 1 comprise a vert~cal leg 2' (figure l-b) or two parallel, spaced apart vertical legs 2 and 3 (figure l-a), extending upwards from a terminal 1' or l respectively, located a few centimetres abovc the lower windshield rim. These vertical legs form the antenna for the reception of metric waves. In figure l(b), the known antenna forms a T with its horizontal portion running at a distance of preferably 7 cm ~rom the upper wind-shield rim. In figure l(a~, each leg, at a given distance, preferably 7 cm from the upper windshield rim, is bent to the left and respectively to the , right to form a horizontal leg for the reception ~ .:
of the ~etric wayes.
According to the invention it has now been found that if each free end of the horizontal leg is bent downward to form a second leg 4 or 4' respec-tively, running parallel to the left and to the right rim respectively of the windshield, the reception of the medium waves is considerably ~ 7 improved. This leg may be further extended by ad-ding to it a fur~her leg 5 ~r 5' respectively, (figure 3 a and b) or by doubling the two last legs or all three legs as indicated at 6, 6' or 7, 7' in figures 4 and 5.
In fact, with such antenna configurations a good reception of the medium waYes has been attained, since they yield an antenna capacity nearing 70/100 pF with a resistance loss of the magnitude of some hundred kohm, while for the metric waves a prevalently resistive antenna impedance of approximately 150 ohm has been found (phase angle not over + 30).
In all these antenna configurations, as precedently mentioned, it has been found that the optimum dis-tance of the antenna corductors from the windshield rim is normally 7 cm and, when the windshield di-mensions permit it without interfering with the area of visibility established for the various windshield types, it has been found ~hat this distance may ad-vantageously be increased to approximately 9-10 cm.
In the con~igurations illustrated in figure 4 the legs 5, S' are loped back at their free end to ex-tend into a leg 6, 6' respectively running parallel to legs 5, 4 and S', 4' respectively. In figure 5 ~o7~753 this leg 6, 5' respectively is further extended to run parallel with the horizontal leg of conductor
2, 3 or 2l, 3' respectively. In the antennas shown in fi~ures 4 and 5, the space between parall~l con-ductors may range between 1.2 and 0.~ cm, preferably 0.4 cm.
The length of the antenna conductors may vary ac-cording to whether the antenna is made from a wire having normally a diameter of 0.1 - 0.2 mm, or by the silk screen process. In fact, when using wire the antenna is sandwiched between the two panes ; which form the windshield~ while an antenna made by the silk screen process may be applied either to the interface of the panes or to the internal face of the windshield. Therefore, since the speed of propagation of the electromagnetic waves is dif-ferent according to where it is intended to receive i the signal, also these parameters must be taken into account.
So for instance, with an antenna structure of the type illustrated in figure 2, on a windshield sized approdimately 60 x 130 cm there has been found a capacity of over 50 pF, a resistance loss of appro-ximately S00 kohm and an antenna impedance variable 1~7~753 between 100 and 200 ohm in the frequency range between 88 and 108 MHz. .
On a windshield of the same dimension, when ex-tending the antenna conductors in the manner shown in figure 3, with the free end of leg 5 or 5' ending at a few centimeters,for instance 2 cm, from the antenna terminal 1, there is an increase of capa-city up to approximately 70 pF, while the other characteristics remain practically the same.
Where the size of the windshield or of some other antenna support is smaller than those above indi-cated, the configurations shown in figure 4 and 5 may be applied, which insure a capacity in the range between 60 and 70 pF, resistance losses of over 400 kohm and an antenna impedance ranging around 150 ohm, with a phase angle of + 30.
The ~ollowing comparative table shows the increase in the volta~e values as measured on the receiver terminals for antennas having a conformation like that illustrated in the figures 2, 3 and 5 respec-tively, as compared with those yielded by the con-ventional antenna shown in figure 1 taken as a unit.
These measurements were made on antennas applied to a windshield sized 60 x 130 cm, for the reception ~o7~7S3 of medium waves and metric waves.
This table shows therefore clearly that the test data confirm the improvements over the known art qbtained by following the concepts of the present ; invention.
It is clear that the idea of the invention is not limited to the embodiments shQwn and described, but includes any possible var?~ance thereof.

T A B L E
.~
. Antenna of fig 1 ri9 2 fig 3 fig 5 .~ W 1 1 ? 3 1,6 1,8 ,.,, _ . F M 1 1,2 1,25 1,35 ~, . ._ ... .

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:;~, ' : ' ' .

.

Claims (18)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A multiband antenna as applied to a window pane, particularly a windshield, for reception of radio signals for a radio receiver having a single antenna input, the antenna comprising: a terminal for connection of the antenna to the receiver; and two conductors electrically connected to said terminal and extending in a generally vertical direction substantially parallel to one another up to a distance a few centimeters from a first rim of said pane, each one of said conductors respectively bending thereafter substantially 90° in opposite directions, so as to define a pair of first legs which extend parallel to said first rim, each one of said conductors being thereafter bent substantially a second 90° in the vicinity of respec-tive second and third rims of said pane so as to define a pair of second legs, said conductors having respective free ends which are looped back to form respective third and fourth legs running respectively substantially parallel to at least said pair of second legs.
2. A multiband antenna according to claim 1, wherein said third and fourth legs run respectively parallel along at least a portion of respective ones of said first pair of legs.
3. A multiband antenna, according to claim 2, wherein each one of said conductors is bent substantially a third 90° in the vicinity of a fourth rim of said pane so as to define a pair of additional legs, said third and said fourth legs running respectively parallel to said pair of additional legs.
4. A multiband antenna, according to claim 1, wherein each one of said conductors is bent substantially a third 90° in the vicinity of a fourth rim of said pane so as to define a pair of additional legs, said third and said fourth legs running respectively parallel to said pair of additional legs.
5. A multiband antenna according to claim 1, wherein the distance between each of said third and said fourth legs and a respective one of portions of said conductors defining said pair of second legs is between substan-tially 1.2 and substantially 0.2 cm.
6. A multiband antenna according to claim 5, wherein said distance is between substantially 1.2 and substantially 0.3 cm.
7. A multiband antenna according to claim 5, wherein said distance is substantially 0.4 cm.
8. A multiband antenna according to claim 1, wherein spacing between respective said rims of said pane and the respective legs is between sub-stantially 7 and substantially 10 cm.
9. A multiband antenna according to claim l, wherein said first rim of said pane is its upper rim and said two conductors extend upward from said terminal.
10. A multiband antenna applied to a window pane, particularly a wind-shield, for the reception of radio signals for a radio receiver having a single antenna input, the antenna comprising: a terminal for connection of the antenna with the receiver input, said terminal being located at a few centimeters from a first rim of said pane; an antenna conductor in electrical contact with said terminal and directed along a vertical path to a distance of a few centimeters from a second rim of said pane and branching off into two oppositely directed legs, which follow along said second rim, are turned respectively substantially 90°, and respectively follow along respective third and fourth rims of said pane and wherein free ends of said legs are looped back to form respective additional legs running parallel to at least portions of said oppositely directed legs.
11. A multiband antenna according to claim 10, wherein each of said respectively additional legs run parallel to respective portions of said oppositely directed legs which follow along said respective third and fourth rims and along at least portions of said oppositely directed legs which follows along said second rim.
12. A multiband antenna according to claim 11, wherein each of said additional legs run parallel to respective portions of said oppositely directed legs which follow along said first rim.
13. A multiband antenna according to claim 10, wherein each of said additional legs run parallel to respective portions of said oppositely directed legs which follow along said first rim.
14. A multiband antenna according to claim 10, wherein the distance between said oppositely directed legs and respective ones of said additional legs is between substantially 1.2 and substantially 0.2 cm.
15. A multiband antenna according to claim 14, wherein said distance ranges between substantially 1.2 and substantially 0.3 cm.
16. A multiband antenna according to claim 14, wherein said distance is substantially 0.4 cm.
17. A multiband antenna according to claim 10, wherein spacing between respective rims of said pane and respective portions of said oppositely directed legs is between substantially 7 and substantially 10 cm.
18. A multiband antenna applied to a window pane, particularly a windshield, for reception of radio signals for a radio receiver having a single antenna input, the antenna comprising: a terminal for connection of the antenna to the receiver; and electrical conductor means connected to said terminal and extending in a generally vertical direction up to a distance a few centimeters from a first rim of said pane and branching off into two oppositely directed conductive legs, the oppositely directed legs extending parallel to said first rim and then turning respectively substan-tially 90° in opposite directions so as to define two further legs extending adjacent respective second and third rims of said pane, the free ends of said further legs being looped back to form respective additional legs running parallel to at least portions of said oppositely directed legs.
CA257,851A 1976-07-27 1976-07-27 Multiband antenna for window panes Expired CA1071753A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA257,851A CA1071753A (en) 1976-07-27 1976-07-27 Multiband antenna for window panes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA257,851A CA1071753A (en) 1976-07-27 1976-07-27 Multiband antenna for window panes

Publications (1)

Publication Number Publication Date
CA1071753A true CA1071753A (en) 1980-02-12

Family

ID=4106514

Family Applications (1)

Application Number Title Priority Date Filing Date
CA257,851A Expired CA1071753A (en) 1976-07-27 1976-07-27 Multiband antenna for window panes

Country Status (1)

Country Link
CA (1) CA1071753A (en)

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