WO2012003632A1

WO2012003632A1 - Antenna for body near-field

Info

Publication number: WO2012003632A1
Application number: PCT/CN2010/075038
Authority: WO
Inventors: 刘朋; 郭羲祥
Original assignee: 海能达通信股份有限公司
Priority date: 2010-07-07
Filing date: 2010-07-07
Publication date: 2012-01-12

Abstract

An antenna for body near-field is provided. The antenna includes a first antenna unit, a second antenna unit, a first feeder, a second feeder and a third feeder. The first antenna unit includes a first baffle-board for avoiding the body to absorb the antenna voltage, a first symmetric-oscillator, and a first isolated component. One end of the first feeder electrically connects with the first symmetric oscillator. The second antenna unit includes a second baffle-board for avoiding the body to absorb the antenna voltage, a second symmetric-oscillator, a second isolated component. One end of the second feeder electrically connects with the second symmetric oscillator. The other end of the first feeder and the other end of the second feeder electrically connect with one end of the third feeder. The addition of baffle-boards to the antenna enables that the radiation-direction patterns of the antenna symmetric-oscillators concentrate on the direction toward the sky, and two antenna units are set suitably so that the antenna-radiation-direction patterns with wider lobes are formed, the loss of gain is reduced when the antenna is close to the body, the structure of the antenna is made simple and the cost of its design becomes less.

Description

Antenna suitable for near field of human body

The present invention relates to the field of antennas, and more particularly to an antenna suitable for the near field of a human body. Background technique

A GPS antenna converts the electromagnetic wave energy of a radio signal received from a satellite into a current that can be ingested by a receiver electronic device. The size and shape characteristics of the antenna determine the antenna's ability to acquire GPS signals. The built-in antenna of the current GPS receiver is a flat antenna or a four-arm helical antenna.

A patch antenna is a microstrip antenna used in the GPS band. It consists of a floor, a radiating sheet and a medium. The medium is generally ceramic. It is radiated by a pair of edges of the four sides and the gap formed by the floor. The radiation is concentrated on the upper hemisphere and has the highest gain in the center direction. The typical gain is 0-3dBi, which is vertical or circular.

The Quadrifilar Helix Antenna consists of four specific curved metal lines that do not require any grounding. This configuration gives the antenna a 3dB gain in either direction, increasing the time it takes for satellite signals to be received. The four-arm helical antenna has a full 360-degree reception capability, so when combined with an electronic device such as a PDA (Personal Digital Assistant), the four-arm helical antenna can receive regardless of the placement position of the PDA, which is different from the use. Flat-panel GPS antennas need to be placed flat for better reception.

The panel antenna is a microstrip antenna. The radiation is formed by the gap between the two opposite edges and the ground. When the antenna is close to the human body, the voltage on the slot antenna is absorbed by the human body, causing the antenna performance to deteriorate sharply and the gain is greatly reduced. Wherever the four-arm helical antenna is placed in the human body, the gain in the opposite direction is absorbed by the human body, which causes a large gain loss, so that only half of the gain pattern satisfies the requirements and is expensive. Summary of the invention

The technical problem to be solved by the present invention is that the gain of the above-mentioned antenna for the prior art is close to the human body. A large-field loss antenna that does not satisfy the gain omnidirectionality and is expensive. The technical solution adopted by the present invention to solve the technical problem is: constructing an antenna suitable for a near field of a human body, comprising: a first antenna unit, a second antenna unit, a first feeder, a second feeder, and a third feeder; The first antenna unit includes a first reflecting plate for preventing the human body from absorbing the antenna voltage, a first symmetrical vibrator, and the first reflecting plate disposed between the first reflecting plate and the first symmetrical vibrator for isolating the first reflecting plate And a first spacer of the first symmetrical vibrator; one end of the first feed line is electrically connected to the first symmetrical vibrator;

The second antenna unit includes a second reflecting plate for preventing the human body from absorbing the antenna voltage, a second symmetrical vibrator, and the second reflecting plate and the second symmetrical vibrator disposed to isolate the second a second spacer of the reflector and the second symmetrical vibrator, and one end of the second feeder is electrically connected to the second symmetrical vibrator;

The other end of the first feed line and the other end of the second feed line are electrically connected to one end of the third feed line.

The invention has the beneficial effects that the reflector is added to the antenna so that the radiation pattern of the antenna symmetry is concentrated in the direction toward the sky. By providing two antenna units, the antenna radiation pattern of the wider lobes can be formed, thereby weakening The effect of the human body on the performance of the antenna reduces the loss of gain when the antenna approaches the human body, forming omnidirectional polarized radiation facing the upper hemisphere. Moreover, the antenna of the present invention has a simple structure and a low design cost. DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

1 is a schematic structural view of a human near-field antenna according to an embodiment of the invention;

2 is a schematic structural view of the first antenna unit shown in FIG. 1;

3 is a schematic structural view of a second antenna unit shown in FIG. 1;

4 is a schematic diagram of a GPS band curve of the human near-field antenna 100 shown in FIG. 1;

FIG. 5 is a gain pattern of the human near-field antenna 100 shown in FIG. 1. detailed description FIG. 1 is a schematic structural view of a human near-field antenna 100 according to an embodiment of the invention. As can be seen from FIG. 1, the human near-field antenna 100 includes: a first antenna unit 101, a second antenna unit 102, a first feeder line, a second feeder line, and a third feeder line.

The first antenna unit 101 is electrically connected to one end of the first feed line, the second antenna unit 102 is electrically connected to one end of the second feed line, and one end of the third feed line unit is electrically connected to the other end of the first feed line and the second feed line, The other end of the three-feed unit is connected to an electronic device that transmits and receives signals.

The human near-field antenna 100 can operate in the GPS band. For the GPS signal, the frequency is 1575 Hz, while the GPS signal has a wavelength of 19.05 cm and a half wavelength of about 9.5 cm.

In an embodiment of the invention, the lengths of the first feed line and the second feed line are equal, that is, the phase difference between the first antenna unit 101 and the second antenna unit 102 is 0 degrees. In still another embodiment of the invention, the first feed line and the second feed line each have a length of about 130 mm. Among them, a coaxial cable can be used as the first feeder, the second feeder, and the third feeder. The specific shape of the first feed line, the second feed line, and the third feed line is not limited and may be, for example, a spiral shape, a polygonal line shape, or the like. Figure 1 shows a polygonal line shape.

In an embodiment of the invention, the specific structures of the first antenna unit 101 and the second antenna unit 102 shown in FIG. 1 are identical. The detailed structure is shown in Figure 2 and Figure 3.

FIG. 2 is a schematic structural view of the first antenna unit 101 shown in FIG. 1. The first antenna unit 101 includes a first reflection plate 101a for preventing the human body from absorbing the antenna voltage, a first symmetrical vibrator 101b, and a first reflection plate 101a disposed between the first reflection plate 101a and the first symmetrical vibrator 101b for isolating the first reflection plate 101a. And a first spacer 101c of the first symmetrical vibrator 101b.

The first reflection plate 101a is made of a metal material such as, but not limited to, copper, iron, or the like. The first spacer 101c (hatched portion in hatching in Fig. 2) is disposed on the first reflecting plate 101a and below the first symmetrical vibrator 101b, and may be made of a non-metallic material such as, but not limited to, plastic or the like. The first symmetrical vibrator 101b (shown by the thick black lines on the first spacer 101c) may be made of a metal material such as, but not limited to, copper foil, and all materials which can serve as antenna symmetrical vibrators can be used.

The specific shape of the first spacer 101c can be designed as needed, and the shape of the first spacer 101c shown in Fig. 2 is identical to that of the first symmetrical vibrator 101b, similar to a strip shape. The size of the first spacer 101c can be adjusted to be as large as the reflector, which is also a preferred solution. 2 is a smaller size than the first symmetric vibrator 101b, but this is shown for convenience of understanding, but this It is not intended to limit the invention. The first spacer 101c may have other shapes as long as it can achieve no electrical contact between the first symmetrical vibrator 101b and the first reflector 101a.

In a preferred embodiment of the invention, the first symmetrical vibrator 101b should be located at the centerline position (symmetric axis position) of the first reflector 101a to ensure minimal frequency drift when approaching the human body. The distance between the first antenna unit 101 and the second antenna unit 102 is preferably set at 1.25 to 1.5 times, so that the gain pattern of the antenna is optimized.

In an embodiment of the invention, the first symmetric vibrator 101b is a half-wavelength symmetric vibrator. If the antenna 100 operates in the GPS band, the total length of the first symmetrical vibrator 101b is half a wavelength, i.e., 9.75 cm.

In general, a symmetric oscillator consists of two symmetrically placed oscillators. As can be seen from FIG. 2, the first symmetric vibrator 101b includes two arms, which are shown as two thick lines in FIG. 2. If the antenna 100 operates in the GPS band and the first symmetric vibrator 101b is a half-wavelength symmetric vibrator, these two 5厘米。 The total length of the arm is 9. 5cm. The two arms are electrically connected to the first feed line. If the first feed line is a coaxial cable, the inner core of the first feed line is connected to one of the two arms, which is the positive pole of the first symmetric vibrator. The outer sheath of the first feed line is connected to the other arm, which is the negative pole of the first symmetric vibrator. Thereby, the signal received by the antenna is transmitted by the first feeder and finally transmitted to the electronic device via the third feeder connected to the electronic device.

FIG. 3 is a schematic structural view of the second antenna unit 102 shown in FIG. 1. In an embodiment of the invention, the specific structure of the second antenna unit 102 is identical to that of the first antenna unit 101. The second antenna unit 102 includes a second reflection plate 102a for preventing the human body from absorbing the antenna voltage, a second symmetrical vibrator 102b, and is disposed between the second reflection plate and the second symmetrical vibrator for isolating the first a second reflector and a second spacer 102c of the second symmetrical vibrator.

The second reflector 102a, the second symmetry oscillator 102b, and the second spacer 102c are similar in structure to the first reflector 101a, the first symmetrical oscillator 101b, and the first spacer 101c shown in FIG. 2, and details are not described herein. . The content of the first antenna unit 101 described in Fig. 2 is applied to the second antenna unit 102.

The second reflection plate 102a may be made of a metal material such as, but not limited to, copper, iron, or the like. The second spacer 102c (hatched portion in FIG. 3) is disposed on the second reflecting plate 102a and below the second symmetrical vibrator 102b, and may be made of a non-metallic material such as, but not limited to, plastic or the like. The second symmetrical vibrator 102 b (shown by the thick black line on the second spacer 102 c ) may be made of a metal material, such as but not Limited to copper foil, all materials that can be used as antenna symmetrical vibrators can be used.

The specific shape of the second spacer 102c can be designed as needed, and the shape of the second spacer 102c shown in Fig. 2 is identical to that of the second symmetrical vibrator 102b, which is similar to the strip shape. The size of the second spacer 102c can be adjusted to be as large as the reflector, which is also a preferred solution. 2, for the sake of easy understanding, the second spacer 102c is shown to be slightly larger in size than the second symmetric vibrator 102b, but this is not intended to limit the invention. The second spacer 102c may have other shapes as long as electrical contact between the second symmetrical vibrator 102b and the second reflecting plate 102a can be achieved.

In a preferred embodiment of the invention, the second symmetrical vibrator 102b should be located at the centerline position (symmetric axis position) of the second reflector 102a to ensure minimal frequency drift when approaching the human body. The distance between the first antenna unit 101 and the second antenna unit 102 is preferably set at 1.25 to 1.5 times, so that the gain pattern of the antenna is optimized.

In an embodiment of the invention, the second symmetrical vibrator 102b is a half-wavelength symmetrical vibrator. If the antenna 100 operates in the GPS band, then the total length of the first person symmetric vibrator 102b is half a wavelength, i.e., 9.5 cm.

As can be seen from FIG. 3, the second symmetric vibrator 102b includes two arms, which are shown as two thick lines in FIG. 3. If the antenna 100 operates in the GPS band and the second symmetric vibrator 102b is a half-wavelength symmetric vibrator, The total length of the arms is 9.5 cm. The two arms are electrically connected to the second feed line. If the second feed line is a coaxial cable, the inner core of the second feed line is connected to one of the two arms, which is the positive pole of the second symmetrical vibrator. The outer skin of the second feed line is connected to the other arm, which is the negative pole of the second symmetric vibrator. The signal received by the antenna is then passed down by the second feeder and finally passed to the electronic device via a third feeder connected to the electronic device.

In an embodiment of the invention, the first feed line and the second feed line are of equal length, each being 130 mm. In practical applications, the antenna 100 can be applied to an electronic device that is close to the human body (near field of the human body), such as a transceiver, and is applied to the GPS band as a GPS receiver. In use, the first antenna unit 101 and the second antenna unit 102 can be placed on both shoulders of the human body, and one antenna unit can be placed on one side, or can be placed at any distance of 260 mm. The first antenna unit 101 and the second antenna unit 102 are electrically connected by the first feeder and the second feeder and connected to the electronic device through the third feeder. The feeders can be designed in different shapes according to actual needs.

The following is a detailed description of the simulation results of the human near-field antenna 100. Applied to antenna 100 Taking the GPS frequency band as an example, the first symmetric vibrator 101 b and the second symmetric vibrator 102 b are half-wavelength symmetric vibrators, and the parameters are set as follows: The first feeder and the second feeder are equal in length (that is, the phase difference is 0 degrees), preferably 130 mm. That is, the sum of the lengths of the first feeder and the second feeder is 260 mm. The first antenna unit and the second antenna unit are placed at the shoulder positions of the human body.

Fig. 4 is a schematic diagram showing the GPS band curve of the human near-field antenna 100 shown in Fig. 1 under the above parameter setting. Figure 5 is a gain pattern of the human near-field antenna 100. It can be seen from Fig. 4 that the return loss is ideal at a frequency of about 1575 MHz, and the performance of the GPS is optimal, that is, the human near-field antenna 100 provided by the present invention achieves better performance in the GPS band.

As can be seen from Fig. 5, the GPS radiation direction can be mostly concentrated in the direction pointing to the sky, the performance of the antenna is better, and the gain pattern is concentrated on the upper hemisphere. In the middle part of Fig. 5, the lobe is small (ie, pointing in the direction of the human head), while the lobes on both sides are wider, and the antenna gain is higher (this is the simulation value of free space), which is about 6dBi. (The gain data for this simulation is the absence of an antenna jacket and mainframe housing, excluding the ideal value of the feeder loss). The positions of ml, m2, m3, and m5 in the figure are the peak points of the gain, where the gains of ml and m3 are the available gains (m2 is the position pointing to the human brain) are greater than or equal to 6dBi, and the position of m4 is the position of OdBi. Used to indicate the lobe width.

In this simulation experiment, the first symmetrical vibrator 101 b and the second symmetrical vibrator 102 b should be located at the center line positions of the first reflecting plate 101a and the second reflecting plate 102a, respectively, to ensure that the frequency drift is minimized when approaching the human body. The distance between the first antenna unit 101 and the second antenna unit 102 is about 1.25 to 1.5 times. At this time, the lobe pattern of the antenna is divided into three, and the lobes in the middle position are narrow, and the lobes on both sides are not too low, the whole The gain pattern is optimal.

The solution is set according to the characteristics of the human body. Of course, in practical applications, the first antenna unit 101 and the second antenna unit 102 can also be placed at other positions of the human body by adjusting the position of the two antenna elements and the phase of the unit feeding. Poor, the same effect, that is, the settings of the two antenna units can be varied.

If the sum of the lengths of the first feed line and the second feed line is adjusted (no longer 260 mm), the difference between the lengths of the first feed line and the second feed line is changed (ie, the phase difference is changed, for example, the phase difference is between 90 degrees and 135 degrees). In addition, the purpose of reducing the influence of the human body on the antenna gain can also be achieved. The relationship between the phase difference and the difference between the lengths of the first feed line and the second feed line is as follows: The difference in length is half a wavelength, and the phase difference is 180 degrees; The difference between the degrees is a quarter wavelength, and the phase difference is 90 degrees. The magnitude and size of the specific change depends on the strength of the antenna's gain pattern. Many changes can be made based on the technical solution of the present invention without departing from the scope of the present invention.

The antenna 100 suitable for the near field of the human body is provided with a suitable size reflective sheet directly under the symmetrical vibrator (without any electrical contact with the symmetrical vibrator), thereby effectively reducing the influence of the human body on the antenna performance, and By adjusting the spacing of the two antenna elements, the maximum lobe width is adjusted to the narrowest, so that the absorption of the human brain is minimized, the influence of the human body on the antenna performance is weakened, and the gain loss of the antenna when approaching the human body is reduced, forming the upward direction. Omnidirectional polarized radiation of the hemisphere. The radiation performance of the antenna provided by the invention is more concentrated in the direction of the sky, and the addition of the reflector not only enhances the directivity of the antenna, but also reduces the influence of the human body in close use, and is suitable for the special environment of the close body. Moreover, the antenna of the present invention has a simple structure and a low design cost.

Claims

Rights request

An antenna suitable for a near field of a human body, comprising: a first antenna unit, a second antenna unit, a first feeder, a second feeder, and a third feeder;

The first antenna unit includes a first reflecting plate for preventing a human body from absorbing an antenna voltage, a first symmetrical vibrator, and a first symmetrical reflector disposed between the first reflecting plate and the first symmetrical vibrator for isolating the first a first spacer of the reflector and the first symmetrical vibrator; one end of the first feed line is electrically connected to the first symmetrical vibrator;

2. The antenna according to claim 1, wherein the first symmetric vibrator and the second symmetric vibrator are both half-wavelength symmetric vibrators.

The antenna according to claim 2, further comprising: the first feed line and the second feed line are equal in length.

The antenna according to claim 3, further comprising: the first feed line has a length of 130 mm.

The antenna according to claim 1, wherein the first symmetrical vibrator is disposed at a center symmetrical position of the first reflecting plate; and the second symmetrical vibrator is disposed at a center of the second reflecting plate Symmetrical position.

The antenna according to claim 1, wherein the first feed line has a polygonal line shape.

The antenna according to any one of claims 1 to 6, wherein the first reflecting plate and the second reflecting plate are made of a metal material.

The antenna according to any one of claims 1 to 6, wherein the first spacer and the second spacer are made of a non-metal material.

The antenna according to any one of claims 1 to 6, wherein the first symmetrical vibrator and the second symmetrical vibrator are made of a metal material.

The antenna according to any one of claims 1 to 6, wherein the antenna operates in a GPS band.