HK1111268B - Wide band dipole antenna - Google Patents

Description

Dipole type broadband antenna

Technical Field

The present invention relates to a dipole type broadband antenna, and more particularly to an antenna for receiving television signals, in particular digital television signals, on a portable electronic device such as a laptop computer, PVA (personal assistant) or other similar apparatus.

Background

Currently, in the market, there are devices that can receive terrestrial digital television or TNT on a laptop or PC. Receiving the TNT signal on the laptop computer enables the computational power of the PC to be used for decoding the digital image stream. This device is sold at best in the form of a box with two interfaces, namely: one RF (radio frequency) interface for connection to an internal or external VHF-UHF antenna and a USB interface for connection to a computer. Examples of this type are given in particular in us patent application 2004/0263417 in the name of MICROSOFT corporation or in us patent 6544075 in the name of ACCTON technology corporation. However, these two documents describe devices comprising a separate antenna, at most a whip or loop type antenna mounted on a USB unit.

Moreover, it has long been known how to use dipole antennas as television signal receiving antennas. In general, a standard dipole antenna comprises two identical arms having a length substantially equal to λ/4 and placed opposite each other. The arms are differently powered (supplied) by a generator. Antennas of this type have been studied since the beginning of electromagnetism and are used in particular for UHF reception and even more recently in wireless networks of the WLAN type.

Disclosure of Invention

The invention thus uses the idea of a dipole type antenna to make a compact broadband antenna, covering the entire UHF band, and associated with an electronic board that can be connected to a portable device by using, in particular, a USB type connector.

The present invention therefore relates to a dipole-type wideband antenna comprising first and second differently powered conductive arms. According to the invention, one of said arms, called first arm, forms at least one cover for the electronic card.

According to a first embodiment, the first arm has the shape of a box in which the electronic card is inserted.

According to a second embodiment, the first arm comprises an upper surface covering the electronic card. Two side surfaces may be combined with this upper surface.

Preferably, the first and second arms are mounted rotatably with respect to each other and each arm has a substantially rectangular shape with a curved profile (profile), which preferably complements in such a way that the two arms can be folded with respect to each other, so that a compact, easily portable antenna is obtained.

According to a characteristic of the invention, the electronic card comprises, at one extremity, a connection port for powering the antenna and, at the other extremity, a connection port to the electronic device. Preferably, the connection port to the electronic device is a USB connection port. Furthermore, the electronic card comprises circuitry for processing television-type signals.

Drawings

Other features and advantages of the invention will appear upon reading the description of the different embodiments, which description is made with reference to the accompanying drawings, in which:

fig. 1 is a side perspective view of a first embodiment of an antenna according to the present invention.

Fig. 2 is a perspective view of the antenna of fig. 1.

Fig. 3 shows an impedance matching curve S11 as a function of frequency for the antenna of fig. 2 with and without an impedance matching circuit, respectively.

Fig. 4 shows a Smith chart (Smith abacus) of the antenna of fig. 2 with and without an impedance matching circuit.

Fig. 5 shows a graph indicating the efficiency of the antenna as a function of frequency with or without an impedance matching circuit.

Fig. 6 is a gain radiation pattern of the antenna of fig. 2.

Fig. 7 is the same representation of fig. 1 in which the second arm occupies a different position.

Fig. 8 shows a graph indicating the impedance matching as a function of frequency for different positions of the arm 2 shown in fig. 7.

Figure 9 shows a graph indicating the impedance match with frequency for different positions of the arm 2 shown in figure 7 when the impedance matching circuit is behind the antenna.

Fig. 10 shows the gain radiation pattern of the antenna of fig. 7 for different positions of the arm 2.

Fig. 11 schematically shows an impedance matching circuit provided at the antenna output.

Fig. 12 is a schematic perspective view of a second embodiment of an antenna according to the present invention.

Fig. 13 and 14 show a graph indicating impedance matching as a function of frequency and a graph indicating antenna efficiency as a function of frequency, respectively, for the antenna of fig. 12 by comparing the antenna of fig. 12 with the antenna of fig. 2.

Fig. 15 is a schematic perspective view of a third embodiment of the present invention.

Fig. 16 and 17 show a graph indicating impedance matching as a function of frequency and a graph indicating antenna efficiency as a function of frequency, respectively, for the antenna of fig. 15 by comparing the antenna of fig. 15 with the antenna of fig. 2.

FIG. 18 shows a schematic perspective view of a fourth embodiment of the invention, an

Fig. 19 is a schematic view of an electronic card used in the present invention.

Detailed Description

To simplify the description, like elements have the same reference numerals as the figures.

With reference to fig. 1 and 2, a first embodiment of a compact broadband antenna according to the invention, usable for receiving terrestrial digital television on a laptop, will be described first.

As schematically shown in fig. 1 and 2, the dipole-type antenna essentially comprises a first 1 and a second 2 conductive arm, which are interconnected by a hinge region 3 at one of the ends of each arm.

More specifically, the arm 2 is constituted by a rectangular plate made of conductive metal, metallized material or other material, and has a length close to λ/4 at the operating central frequency, i.e. close to 112mm for operation in the UHF band (the band between 460 and 870 MHz). The arm 2 has a straight portion 2a and a curved portion 2b enabling connection to the other arm 1 at the level of the area 3. The arm 1 has such a form that it can be used at least as a cover for an electronic card, which will be described in more detail below.

More specifically, the arm 1 shown in fig. 1 and 2 comprises a rectangular portion 1a forming a unit into which the card can be inserted, and it is extended by a curved portion 1b, said curved portion 1b forming a gradual taper (gradual tapering) which enables the energy to be radiated gradually, and in this way enhances the impedance matching for a larger frequency band. The length of the arm 1 is also obviously equal to lambda/4. The arm 1 is made of metal, metalized material or other material.

As shown in fig. 1, in the embodiment shown, the arms 1 and 2 have almost the same overall length, i.e. a length of 118.7 mm. More specifically, the straight portion has a length of 70mm and a width of 25 mm. Furthermore, the box-shaped arm 1 has a height of 10 mm. The two arms 1 and 2 are linked to each other at the level of a hinge area 3, said hinge area 3 comprising in 3a connection elements enabling the connection of an antenna to a generator or to a receiver circuit for processing electromagnetic signals. In order not to disturb the electromagnetic operation of the antenna, the hinging region comprises a connecting element made of a material that is relatively transparent to radio waves, whereas the electrical connection is provided by means of metal strands, coaxial cables or similar cables connected to a generator or receiver circuit for processing electromagnetic signals. In order to prevent short-circuiting between the metal strand and the arm 2, an opening (opening) is required in the arm 2.

As mentioned above, the two arms 1 and 2 are made of an electrically conductive material, in particular a metallic material. Thus, the two arms 1 and 2 can be made from a metal sheet by cutting the sheet.

The antenna of fig. 2, showing the dimensions given above, was simulated using commercial electromagnetic software (IE 3D). In these simulations, the antenna is assumed to be in air and to have good conductivity (σ > -5.10⁷S/m) of a conductive material. The results of the simulation are given in the curves of fig. 3 to 6, which mainly relate to the simulation of the antenna itself and when the antenna is connected to an impedance matching circuit such as described with reference to fig. 11.

Fig. 3 shows impedance matching curves for the antenna of fig. 2 with and without an impedance matching circuit. These curves show that the impedance matching unit can obtain good impedance matching over the entire UHF band (i.e., the frequency band between 460-. This is confirmed on the smith chart of fig. 4.

Fig. 5 shows a graph indicating the efficiency of the antenna with and without an impedance matching circuit. The curves obtained confirm the previous results and show that when using an impedance matching circuit, an antenna efficiency of more than 80% is obtained for the entire UHF band.

The radiation pattern of fig. 6 is a gain radiation pattern confirming that the antenna of fig. 2 operates as a dipole antenna.

As described above, the arm 2 of the antenna is mounted rotationally relative to the arm 1 in such a way that the antenna is oriented for optimal reception. In fig. 7, different positions of the arm 2 with respect to the arm 1 are shown, namely: a position, referenced 20, in which the angle oc between the two arms is equal to 0 °, a position, referenced 21, in which the angle oc between the two arms is significantly equal to 30 °, a position, referenced 22, in which the angle oc formed by the two arms is significantly equal to 45 °, a position, referenced 23, in which the angle oc between the two arms is significantly equal to 60 °, and a position, referenced 24, in which the angle oc between the two arms is significantly equal to 90 °.

In order to determine the effect of the inclination (inclination) of the arm 2 with respect to the arm 1, different positions of the arm were simulated. The results of these simulations are provided in fig. 8, 9 and 10, respectively.

Fig. 8 shows different curves indicating impedance matching as a function of frequency for different positions of the arm 2. It will be noted that: when the value of the angle oc is low, the antenna is naturally impedance-matched for high frequencies and vice versa. Actually, the electric field E is easily established at low frequencies when the angle ∈ 0 °, and at high frequencies when the angle ∈ ═ 90 °, respectively.

Figure 8 provides the results for the antenna itself. In this case, the antenna is not impedance matched across UHF frequencies. If an impedance matching unit such as that shown in fig. 11 is used, the impedance matching curve of fig. 9 is obtained in this case. According to these curves, the high band has a good impedance match for all positions of the arm 2 with a factor S11 of less than-6 dB, and the low band has a good impedance match for positions of the arm 2 between 0 ° and 60 ° with a factor S11 of less than-6 dB.

Furthermore, fig. 10 shows the radiation pattern at a frequency of 660MHz for various positions of the arm 2 of the antenna. The radiation pattern is inclined according to the angle of inclination ∞. The inclination may optimize reception of the digital television signal.

An impedance matching unit that can be used in the present invention is schematically shown in fig. 11. In the figure, an antenna a is connected to a unit constituted by an inductor L and a capacitor C. The antenna is connected in series with a capacitor C, which is connected to a low noise amplifier LNA, while an inductor L is mounted between ground and the connection point of the antenna and the capacitor C.

In order to obtain good impedance matching, the values of the capacitor C and the inductor L are such that C-5 pF and L-15 nH. The impedance matching unit is optimized for arms tilted at an angle equal to 60 °.

With reference to fig. 12, 13 and 14, a variation of the first embodiment of the present invention will now be described. As shown in fig. 12, in this case the antenna comprises an arm 2 identical to the arm 2 of fig. 2 and an arm 1 constituted only by the upper face 12 of the box forming the arm 1 of fig. 2. In this case, the impedance matching curve and the efficiency curve shown in fig. 13 and 14, respectively, are obtained. The curves of fig. 13 comparing the impedance match of the antenna of fig. 12 with the impedance match of the antenna of fig. 2 indicate that: a good impedance match is still obtained over the entire UHF band. The curves of fig. 14 show that: in this case, since the side wall and the lower wall of the arm 1 of fig. 2 are removed, the efficiency of the antenna of fig. 12 is lower than that of the antenna of fig. 2 in the low band.

With reference to fig. 15, 16 and 17, a third embodiment of the present invention will now be described. In this case, the arm 2 is identical to the arm 2 of the antenna of fig. 2 and 12, while the arm 1 comprises only an upper surface 1c and a lateral surface 1 d. In this case, the arm 1 forms a cover to be mounted to the electronic card. The simulation results shown in fig. 16 and 17 demonstrate that: this example gives significantly similar results to the embodiment of fig. 2. The embodiment has the advantage that it can be more easily industrialized than the embodiment of fig. 2.

A description will now be given of another embodiment of the antenna according to the present invention with reference to fig. 18. In this case, the arm 10 is constituted by an element having the shape of a rectangular box whose upper surface is stamped (stamp) in such a way as to obtain the part 10 c. The stamped portion may receive the arm 20 when the arm 20 is folded for shipping. The arm 20 has a shape corresponding to a semi-ellipse. The arms 10 and 20 are of substantially equal size and correspond to about lambda/4 at the desired operating frequency. As in the case of the other figures, the arms 10 and 20 are connected to each other at the level of the hinge area 30 in such a way that they can rotate relative to each other.

With reference to fig. 19, an embodiment of an electronic card according to the invention will now be described, the arm 1 of the antenna forming a cover or box for this electronic card. The electronic card may include all integrated circuits necessary for processing digital television signals. Thus, as shown in fig. 14, this card 100 comprises a low noise amplifier 101, said low noise amplifier 101 being connected at the output of the antenna at the level of the rotation area 3 or 30 of the antenna, the signal from the LNA amplifier being sent to a tuner 102 and then to a demodulator 103 connected to a USB interface 104. The electronic card features a USB connection port 105. The electronic card may feature shielding of the RE part, if necessary.

As will be apparent to those skilled in the art: other types of connection ports enabling connection to the electronic device may be used, such as formats for memory cards (compact flash, SD, XD, etc.).

The electronic card can be manufactured in such a way that it can be easily inserted into the arms 1 forming the box as shown in fig. 2, so that it has a length of between 70-80mm and a width of between 15-25 mm.

It is clear that the above described electronic card constitutes only one example of an electronic card that can be used in the context of the present invention. According to a variant of embodiment, this card can also be integrated into a standard USB piece (key) for carrying personal data, photos or music.

Claims (6)

1. A compact UHF dipole-type broadband antenna comprising a first conductive arm (110) and a second conductive arm (220) differently powered, connected to each other at the level of a hinge region (3) located at one of the ends of each arm, said hinge region comprising connection elements for connecting the antenna to processing circuits, one of said arms, called first conductive arm, forming at least one cover for an electronic card, each arm having a substantially rectangular shape extended by a bend (1b, 2b) at the level of said hinge region to obtain a larger frequency band.

2. The antenna of claim 1, wherein: the first conductive arm (1) has the shape of a box (10), the electronic card being inserted in the box (10).

3. The antenna of claim 1, wherein: the first conductive arm comprises an upper surface (1c) covering the electronic card and two lateral surfaces associated with said upper surface to form a cover.

4. The antenna of claim 1, wherein: the first conductive arm (1, 10) and the second conductive arm (2, 20) each have a length equal to λ/4 at an operating center frequency of the antenna.

5. The antenna of claim 1, wherein: the first (1, 10) and second (2, 20) conductive arms have complementary profiles that enable them to be folded together.

6. The antenna of claim 1, wherein: the electronic card (100) comprises at one of its ends a connection port for powering the antenna and at the other end a connection port to an electronic device.