CN100364171C - Planar dual-frequency monopole antenna - Google Patents

Abstract

A planar dual-band monopole antenna. An antenna capable of receiving signals of different frequency bands, having a short length and a small size is provided, which comprises a dielectric substrate; a microstrip line printed on a surface of the dielectric substrate and having one end as a signal feed-in end; a grounding metal surface printed on the other surface of the dielectric substrate; the low-frequency radiator extends from the other end of the microstrip line to the direction other than the position opposite to the grounding metal surface on the surface where the microstrip line is located, extends to one side direction of the longitudinal axis of the microstrip line after extending for a preset length, and continues to extend to the position adjacent to the position opposite to the grounding metal surface in the direction opposite to the grounding metal surface after extending for the preset length; and the high-frequency radiator extends from the other end of the microstrip line to the direction other than the position opposite to the grounding metal surface, and extends to the other side of the longitudinal axis after extending for a preset length to form a plane, so that the high-frequency radiator and the low-frequency radiator are respectively positioned at two sides of the longitudinal axis of the microstrip line.

Description

Planar dual-band monopole antenna

technical field

The invention belongs to antennas, in particular to a planar double-frequency monopole antenna.

Background technique

Traditionally, the antennas arranged in parallel on a general TV set are called Lecher (Lecher) lines. As shown in Figure 1, when the radiating metal tubes 14 arranged in parallel on this antenna, such as copper tubes, are very close together, currents flowing in opposite directions will be induced, causing electromagnetic fields in opposite directions to be radiated. produce radiation.

Therefore, in order to allow the antenna to effectively radiate radio waves in a small space, as shown in Figure 2, traditionally, the front ends of the Lecher wires are bent 90° in opposite directions so that the current on them is directed toward the flow in the same direction, thus forming what is now called a dipole (dipole) antenna. The dipole antenna uses a balanced transmission line as the feed line 24. The two signal line terminals 242 of the balanced structure transmission line extend the same length in opposite directions respectively. The length of each signal line terminal 242 is about the resonance wavelength (λ ), so its total length is about one-half of the resonant wavelength. In this way, the dipole antenna can use two quarter-wavelength signal line terminals 242 as radiators, so this kind of antenna can also be called a half-wavelength dipole antenna, which is generally designed with a single frequency.

Traditionally, in order to make this kind of antenna lighter, thinner and shorter, the industry has fabricated this kind of dipole antenna on a printed circuit board to make a microstrip monopole antenna.

As shown in Figures 3 and 4, the microstrip monopole antenna includes a dielectric substrate 37, a microstrip line 34 printed on one side of the dielectric substrate 37 with one end as a signal feed-in terminal 341, and a microstrip line 34 printed on the dielectric substrate 37. The other side of the electrical substrate 37 corresponds to the ground metal plane 38 at the position of the microstrip line 34 . The other end of the microstrip line 34 extends an inverted L-shaped radiator 342 to a position other than the grounding metal plane 38, forming a so-called monopole antenna. The monopole antenna utilizes the mapping principle (Image theory) generated by the grounded metal surface 38 to map the microstrip line 34 and the inverted L-shaped radiator 342 of this unbalanced structure to form a dipole antenna equivalent Radiator structure, this kind of monopole antenna is also generally single-frequency design.

In recent years, due to the great increase in the market demand for mobile communication products, the development of wireless communication has become more rapid. Among the many wireless communication standards, the most eye-catching one is the Institute of Electrical and Electronics Engineers (hereinafter referred to as: IEEE) 802.11 WLAN Wireless Local Area Network protocol, IEEE 802.11 protocol was formulated in 1997. This protocol not only provides many unprecedented functions in wireless communication, but also provides solutions that enable wireless products of various brands to communicate with each other. The formulation of the agreement undoubtedly opened a new milestone for the development of wireless communication.

However, in August 2000, IEEE made the 802.11 protocol a joint agreement between the Institute of Electrical and Electronics Engineers (IEEE)/American National Standards Institute (ANSI) and the International Organization for Standardization (ISO)/International Electrotechnical Council (IEC). The standard has been further revised, and two important contents have been added to the revised content, namely the IEEE802.11a agreement and the IEEE802.11b agreement. According to the provisions of the two agreements, in the extended standard entity layer, Its operating frequency bands must be set at 5 billion hertz (5GHz) and 2.4 billion hertz (24GHz) respectively. Therefore, when wireless communication products want to use the two wireless communication protocols at the same time, the aforementioned traditional antennas cannot meet this requirement, and must be based on According to the requirements of the frequency band, install multiple antennas. However, this not only increases the cost of components and installation procedures, but also requires more space on wireless communication products to install antennas, so that the size of wireless communication products cannot be easily reduced to meet the trend of thin, light and small designs.

Contents of the invention

The object of the present invention is to provide a planar dual-frequency monopole antenna capable of receiving signals of different frequency bands, short in length and small in size.

The invention comprises a dielectric substrate; a microstrip line printed on a surface of the dielectric substrate, one end of the micro wire is used as a signal feed-in end, and the end of the micro wire opposite to the signal feed-in end forms a It is the other end of the micro-wire; a grounded metal surface is printed on the opposite surface of the dielectric substrate and the surface where the microstrip line is located, and the position of the grounded metal surface is opposite to the position of the microstrip line; a low-frequency radiator , the low-frequency radiator extends from the other end of the microstrip line to a direction other than the position opposite to the ground metal surface on the surface where the microstrip line is located, the extension direction is formed as the longitudinal axis direction of the microstrip line, and the low-frequency radiator is in the After extending for a predetermined length, it extends toward one side of the longitudinal axis of the microstrip line, and after extending a predetermined length toward one side of the longitudinal axis, it continues to extend toward the position opposite to the grounding metal surface on the surface where the microstrip line is located until it is adjacent to and grounding The position opposite to the metal surface; and a high-frequency radiator, the high-frequency radiator extends from the other end of the microstrip line to a direction other than the position opposite to the grounded metal surface on the surface where the microstrip line is located, and extends on the surface of the microstrip line After the line is extended for a predetermined length, it is extended to the other side of the longitudinal axis of the microstrip line to form a plane, so that the high-frequency radiation and the low-frequency radiator are respectively located on both sides of the longitudinal axis of the microstrip line.

Wherein: the lengths from the other end of the microstrip line to the free ends of the low and high frequency radiators are respectively equal to a quarter of the wavelength of each frequency band in the dual frequency bands to be designed.

Since the present invention includes a dielectric substrate; a microstrip line is printed on a surface of the dielectric substrate, and one end of the microstrip line is used as a signal feed-in end, and the end of the micro-wire opposite to the signal feed-in end Formed as the other end of the micro-wire; a grounded metal surface, printed on the other surface of the dielectric substrate opposite to the surface where the microstrip line is located, and the position of the grounded metal surface is opposite to the position of the microstrip line; a low-frequency radiation The other end of the microstrip line extends in a direction other than the position opposite to the ground metal surface from the other end of the microstrip line, the extension direction is formed as the longitudinal axis direction of the microstrip line, and after extending a predetermined length The direction of one side of the longitudinal axis of the microstrip line extends, and after extending a predetermined length to one side of the longitudinal axis, the surface where the microstrip line is located continues to extend in the direction opposite to the grounded metal surface to a position adjacent to the position opposite to the grounded metal surface ; and a high-frequency radiator, which extends from the other end of the microstrip line to a direction other than the position opposite to the grounded metal surface on the surface where the microstrip line is located, and after the microstrip line extends a predetermined length The direction extending to the other side of the longitudinal axis of the microstrip line is defined as a plane, so that the high-frequency radiator and the low-frequency radiator are respectively located on both sides of the longitudinal axis of the microstrip line. When the present invention operates in the two frequency bands stipulated in the IEEE802.11a agreement and the IEEE802.11b agreement, the microstrip line other than the grounding metal surface is extended from one side of the longitudinal axis to the lower and high-frequency radiators to respectively receive American electronic motors The measurement results of dual-band signals stipulated in the IEEE802.11a protocol and IEEE802.11b protocol of the Institute of Engineers show that they can indeed be used to receive dual-band signals respectively. Not only can it receive signals of different frequency bands, but it is also short in length and small in size, thereby achieving the purpose of the present invention.

Description of drawings

Figure 1 is a schematic front view of a traditional Lecher line structure.

Fig. 2 is a schematic front view of a traditional dipole antenna structure.

FIG. 3 is a schematic perspective view of the structure of a traditional microstrip monopole antenna.

Fig. 4 is a schematic cross-sectional view of the structure of a traditional microstrip monopole antenna.

Fig. 5 is a schematic perspective view of the structure of Embodiment 1 of the present invention.

Fig. 6 is a schematic perspective view of the second embodiment of the present invention.

FIG. 7 is a schematic diagram of measurement results of Embodiment 1 of the present invention.

FIG. 8 is a schematic diagram of measurement results of Example 2 of the present invention.

Detailed ways

Embodiment one

As shown in Figure 5, the present invention includes a dielectric substrate 57, a microstrip line 54 printed on one side of the dielectric substrate 57 with one end as a signal feed-in terminal 541, and a microstrip line printed on the other side of the dielectric substrate 57. Corresponding to the ground metal plane 58 of the microstrip line 54 .

The other end of the microstrip line 54 extends in a direction corresponding to a position other than the ground metal surface 58 , and after extending for a predetermined length, a low-frequency radiator 542 and a planar high-frequency radiator 543 are respectively extended from both sides of the longitudinal axis.

After extending for a predetermined length, the low frequency radiator 542 continues to extend in a direction corresponding to the grounded metal plane 58 to a position corresponding to the adjacent grounded metal plane 58 .

The planar high-frequency radiator 543 can increase the high-frequency resonance bandwidth.

In this way, the low and high frequency radiators 542 and 543 are respectively used to receive signals of different frequency bands.

Embodiment two

As shown in Figure 6, the present invention includes a dielectric substrate 67, a microstrip line 64 printed on one side of the dielectric substrate 67 with one end as a signal feed-in terminal 641, whose input impedance is fixed to 50 ohms (Ω), and printed The other side of the dielectric substrate 67 corresponds to the ground metal plane 68 of the microstrip line 64 .

The other end of the microstrip line 64 extends in a direction corresponding to a position other than the ground metal surface 68 , and after extending for a predetermined length, a low-frequency radiator 642 and a planar high-frequency radiator 643 are respectively extended from the same side of the longitudinal axis.

After extending for a predetermined length, the low frequency radiator 642 continues to extend in a direction corresponding to the grounding metal surface 68 to a position corresponding to the adjacent grounding metal surface 68 and maintain a certain distance therebetween.

The high-frequency radiator 643 which is a plane can increase the bandwidth of high-frequency resonance, and it is kept at a certain distance from the low-frequency radiator 642 .

In this way, the low and high frequency radiators 642 and 643 are respectively used to receive signals of different frequency bands.

In Embodiment 1 (2) of the present invention, since the low and high frequency radiators 542, 543 (or 642, 643) are used to receive signals of different frequency bands respectively, so by corresponding to the grounding metal surface 58 (or 68) other than The length of the microstrip line 54 (or 64) extending to the free ends of the low and high frequency radiators 542, 543 (or 642, 643) should have a certain proportional relationship with the different resonant frequencies to be designed for the antenna.

The present invention extends from the microstrip line 54 (or 64) other than the grounding metal plane 58 (or 68) to the length of the free ends of the low and high frequency radiators 542, 543 (or 642, 643) to be approximately equal to the two pairs of intended design respectively. A quarter of the wavelength of each frequency band in the frequency band is the best, and the low and high frequency radiators of different lengths are used to receive the dual-band signals stipulated in the IEEE802.11a agreement and the IEEE802.11b agreement.

As shown in Figure 5, in the first embodiment, the microstrip line 54, the low-frequency radiator 542, the high-frequency radiator 543, and the ground metal surface 58 are printed to a flat plate shape with a thickness of about 0.8mm and a dielectric coefficient of about 4.3-4.7. On the dielectric substrate 57 , the width of the microstrip line 54 and the low frequency radiator 542 is about 1 mm; the length of the low frequency radiator 542 is about 18 mm. The area of the high-frequency radiator 543 is about 80 mm ² .

As shown in Figure 7, Embodiment 1 of the present invention operates in two frequency bands of 2.4-2.5 billion hertz (2.4-2.5 GHz) and 5.15-5.85 billion hertz (5.15-5.85 GHz) stipulated in the IEEE802.11a protocol and the IEEE802.11b protocol , the measurement result of its return loss (Return Loss) is:

△1: 2.4 billion hertz (2.4GHz); -14.2750 decibels (dB);

△2: 2.5 billion hertz (2.5GHz); -15.601 decibels (dB);

△3: 5.15 billion hertz (5.15GHz); -11.887 decibels (dB);

△4: 5.35 billion hertz (5.35GHz); -20.362 decibels (dB);

△5: 5.85 billion hertz (5.85GHz); -12.599 decibels (dB);

That is, both are better than 11 decibels (dB). Therefore, the measurement results show that the planar dual-band monopole antenna of the present invention can indeed be used to receive dual-band signals respectively.

As shown in Figure 6, the microstrip line 64, low-frequency radiator 642, high-frequency radiator 643 and ground metal surface 68 in the second embodiment are printed on a flat plate with a thickness of about 0.8mm and a dielectric coefficient of about 4.3-4.7 On the dielectric substrate 67, the width of the microstrip line 64 and the low frequency radiator 642 is about 1mm; the length of the low frequency radiator 642 is about 17mm; the area of the high frequency radiator 643 is about 77mm ² .

As shown in Figure 8, Embodiment 2 of the present invention operates at 232 million hertz (0.232 GHz), 2.4-2.5 billion hertz (2.4-2.5 GHz) and 5.15-5.85 billion hertz ( 5.15～5.85GHz) two frequency bands, the measured return loss (Return Loss) measurement results are:

△1: 2.4 billion hertz (2.4GHz); -11.841 decibels (dB);

△2: 2.5 billion hertz (2.5GHz); -16.220 decibels (dB);

△3: 5.15 billion hertz (5.15GHz); -25.878 decibels (dB);

△4: 5.85 billion hertz (5.85GHz); -17.554 decibels (dB);

△5: 232 million hertz (0.2 32GHz); -0.16870 decibels (dB);

That is, both are better than 11 decibels (dB). Therefore, the measurement results show that the planar dual-band monopole antenna of the present invention can indeed be used to receive dual-band signals respectively.

Claims (2)

1. plane formula double frequency mono-polar antenna comprises:

A dielectric medium substrate;

A microstrip line is printed on dielectric medium substrate one surface, with an end of this microstrip line as the signal feed side; An end relative with this signal feed side of this little electric wire forms the other end of little electric wire;

A grounding metal plane be printed on dielectric medium substrate and another relative surperficial face of surface, microstrip line place, and the position of this grounding metal plane is relative with the position of microstrip line;

A low frequency radiation body, this low frequency radiation body is by other end extension of the direction beyond the position relative with grounding metal plane on surface, microstrip line place of microstrip line, this bearing of trend forms the longitudinal axis direction of microstrip line, and this low frequency radiation body side direction to the longitudinal axis of microstrip line after definite length extended extends, it is characterized in that

Described low frequency radiation body continues extend to contiguous with grounding metal plane relative position on surface, microstrip line place to the locality relative with grounding metal plane after longitudinal axis one side direction definite length extended; And

A high frequency radiation body, this high frequency radiation body on surface, microstrip line place by the described other end of microstrip line to the grounding metal plane relative position beyond direction extend, and after the microstrip line definite length extended, extend to the opposite side direction of microstrip line longitudinal axis and be the plane, make high frequency radiation body and low frequency radiation body lay respectively at the both sides of microstrip line longitudinal axis.

2. plane formula double frequency mono-polar antenna according to claim 1 is characterized in that, from the described other end of described microstrip line to low, the free-ended length of high frequency radiation body, equals 1/4th length of each band wavelength in the two-band of institute's desire design respectively.

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