WO2010075648A1

WO2010075648A1 - Improved inverted f antenna and wireless communication apparatus

Info

Publication number: WO2010075648A1
Application number: PCT/CN2008/073885
Authority: WO
Inventors: 刘朋; 郭羲祥; 任涛
Original assignee: 深圳市好易通科技有限公司
Priority date: 2008-12-31
Filing date: 2008-12-31
Publication date: 2010-07-08

Abstract

An improved inverted F antenna and wireless communication apparatus with the antenna, the antenna mainly includes the first conductor part facing a circuit board, a ground conductor part connecting with the first conductor part and electrically connecting to the ground point of the circuit board, and a feed conductor part connecting with the first conductor part and electrically connecting to the feed point of the circuit board; the tail of the first conductor part is set as a helical structure. Setting the tail of the first conductor part as a helical structure enables the resonance and small volume of the antenna, which thereby enables the antenna on a lower frequency to be internally set in the wireless communication apparatus. Thus the wireless communication apparatus is portable.

Description

An improved inverted F antenna and wireless communication device

Technical field

The present invention relates to a radio frequency antenna, and more particularly to an improved inverted-F antenna and wireless communication device.

At present, handheld terminal communication devices have become very popular, and miniaturized and portable communication tools are increasingly popular. The antennas of the conventional handheld terminals are designed according to a half-wavelength symmetric matrix model, that is, the size of the antenna and the host are half of the operating wavelengths, which can obtain better antenna performance. However, when the frequency used is lower, such as 400MHz, 155MHz, 80MHz, the working wavelength is longer, and the corresponding antenna will be very long, which is very unfavorable for carrying. In the prior art, the antenna is usually bent from the middle to be parallel to the ground, and the size of the antenna is also reduced to some extent, so that the antenna has a lower profile, that is, an inverted L-shaped antenna, see FIG. It is a schematic structural diagram of an L-shaped antenna in the prior art.

The disadvantage of the inverted L antenna is that the impedance is low, the input impedance is small, and the bandwidth is narrow. Usually, a matching circuit needs to be added, but the addition of the matching circuit affects the bandwidth and increases the loss. Therefore, the self-resonance of the antenna is needed to solve the above problem. A grounding point is introduced near the antenna feeding point, which can realize self-resonance of the antenna and achieve impedance matching, that is, an inverted F antenna (IFA). Referring to FIG. 1b, it is a schematic structural diagram of the inverted F antenna in the prior art. The existing IFA is widely used for its low profile shape, but when used for, for example, mobile phones, walkie-talkie-sized terminal devices, the size is still large, such as the 468MHz civilian walkie-talkie band, the wavelength is 640mm, even if it is IFA, It is not possible to reduce its volume to the built-in level. This does not allow for a "wireless" design of its appearance, which is both inconvenient and aesthetically pleasing.

Summary of the invention

The technical problem to be solved by the present invention is that, in view of the above-mentioned prior art, the antenna of the lower frequency band cannot be built into the host to make it inconvenient to carry, and a small size can be realized, and the antenna of the lower frequency band can be realized. Inverted F antenna and wireless communication equipment that are convenient to carry and beautiful in appearance to the host.

The technical solution adopted by the present invention to solve the technical problem thereof is to provide an improved inverted-F antenna, which mainly a first conductor portion facing the circuit board, a ground conductor portion connected to the first conductor and electrically connected to a ground point of the circuit board, a feed connected to the first conductor and electrically connected to a feeding point of the circuit board An electric conductor portion, and a tail portion of the first conductor portion is disposed in a spiral structure.

In the improved inverted-F antenna of the present invention, the first conductor portion is parallel to the circuit board, the ground conductor portion and the feed conductor portion are both perpendicular to the circuit board, and the spiral structure is located at the feed One side of the electrical conductor portion.

In the improved inverted-F antenna according to the present invention, the distance between the end of the spiral structure adjacent to the feed conductor portion and the portion of the feed conductor is greater than the pitch of the turns of the spiral structure.

In the improved inverted-F antenna according to the present invention, the spiral structure is close to the end of the feed conductor portion and the feed conductor portion is twice the pitch of the turns of the spiral structure.

In the improved inverted- _F antenna according to the present invention, the diameter of the coil of the spiral structure is 4.5 mm_6 mm. In the improved inverted- _F antenna of the present invention, the distance between the feeding point and the grounding point is 8 mm-lOmmo. In the improved inverted-F antenna of the present invention, the distance between the first conductor portion and the circuit board is 10 mm _ 15 mm.

In the improved inverted-F antenna of the present invention, the spiral structure has a spiral length of 20 mm to 40 mm. In the improved inverted-F antenna of the present invention, the spiral structure has a spiral length of 29 mm.

In order to solve the above technical problem, the present invention further provides a wireless communication device, which mainly includes an inverted F antenna and a motherboard for transmitting a communication signal to at least the outside or receiving a communication signal from the outside, and the inverted F antenna includes: a first conductor portion of the circuit board, a ground conductor portion connected to the first conductor and electrically connected to a ground point of the circuit board, a feed conductor portion connected to the first conductor and electrically connected to the feed of the circuit board The tail portion of the first conductor portion is disposed in a spiral structure.

An improved inverted-F antenna and wireless communication device embodying the present invention, since the tail portion of the first conductor portion of the antenna facing the circuit board is provided in a spiral structure, which combines the advantages of the inverted-F antenna and the helical bat rotor antenna, It reduces the size of the antenna, and the spiral structure makes it possible to achieve resonance, so that the antenna of the lower frequency band can be built into the host, and the communication device can be wirelessized, which is convenient to carry and beautiful in appearance. [16] The present invention will be further described with reference to the accompanying drawings and embodiments, in which:

[17] Figure la is a schematic structural view of an L-shaped antenna in the prior art;

[18] Figure lb is a schematic structural view of an inverted F antenna in the prior art;

2 is a schematic structural view of an embodiment of the improved inverted-F antenna built in the host of the present invention;

Figure 3 is a radiation pattern of an embodiment of the present invention;

4 is an impedance graph of an embodiment of the present invention.

detailed description

[22] The present invention is directed to an improved inverted F antenna in which prior art antennas are not capable of implementing built-in defects in the lower frequency band. This antenna combines the features of an IFA antenna and a bat rotor antenna (Helix antenna) to replace the existing linear form of the radiating arm of the horizontal portion of the IFA antenna in a spiral.

[23] Referring to Fig. 2, it is a schematic structural view of an embodiment of the improved inverted-F antenna built in the host. An inverted F antenna is disposed at the upper end of the motherboard 4, and both the antenna and the motherboard 4 are built in the casing. The inverted F antenna includes a first conductor portion 1 facing the circuit board of the motherboard 4, a feed conductor portion 3 electrically connected to a phase perpendicular to the first conductor portion 1 extending along a feed point of the circuit board, and The first conductor is connected and electrically connected to the ground conductor portion 2 of the ground point of the circuit board. The first conductor portion 1 is parallel to the circuit board, and the ground conductor portion 2 and the feed conductor portion 3 are perpendicular to the circuit board.

Further, the tail portion of the first conductor portion 1 on the side of the feed conductor portion 3 is provided as a spiral structure 11. The helical structure 11 can achieve resonance of the antenna. The size of the helix 均有 has an effect on the antenna bandwidth and impedance. In radio communication, the impedance of the antenna does not match the impedance of the feeder or the impedance of the antenna does not match with the impedance of the transmitter. The high-frequency energy will be reflected and folded back, and the standing wave will be merged with the forward part of the interference.

VSWR reflects the forward and reflected waves in the antenna, VSWR = (1 + Γ) I (1-Γ), Γ is the reflection coefficient: Γ = (ZL-ZO) I (ZL + ZO), where ZL is the load Impedance,

Z0 is the characteristic impedance. For example, VSWR = 2: 1吋, reflection coefficient Γ = 1/3,

That is, 1/3 of the voltage is reflected back. In the embodiment of the present invention, the antenna height, that is, the distance between the first conductor portion 1 and the circuit board is 15 mm, the width is 40 mm, and the VSWR is less than 2.5, and the matching is good; if the antenna height is lOmm, the VSWR is less than 4.0. The height of the antenna is 10mm - 15mm.

[25] The size of the helical structure 11 affects the bandwidth and gain of the antenna. The diameter of the turns of the spiral portion is usually 5mm, when its diameter is 6mm, it will increase the antenna bandwidth, and the antenna will reduce the gain of the antenna. When it is 4mm in diameter, it will reduce the bandwidth and the gain will not increase. Preferably, the diameter of the coil is 4.5mm. Up to 6 mm.

[26] The helical portion of the antenna is separated from the feeding conductor portion by a small distance, and the distance cannot be too close. Therefore, preferably, the distance between the end of the spiral structure 11 close to the feeding conductor portion and the feeding conductor portion 3 is larger than the spiral The pitch of the turns of the structure 11; more preferably, the end of the spiral structure 11 near the feed conductor portion is twice the distance of the feed conductor portion 3 from the pitch of the turns of the spiral structure 11.

[27] The helical length of the helical structure 11 of the first conductor portion of the antenna is an important parameter determining the bandwidth of the antenna, so the length of the spiral is relatively long, but if the overall length of the antenna, that is, the horizontal length of the first conductor portion exceeds the host The width of the antenna will produce the maximum gain direction offset, and the overall length of the antenna should not exceed the width of the host. The length of the spiral is 20mm吋, VSWR<2.5 in the 10MHz bandwidth; when the length is 28mm吋, the VSWR<2.0 in the 10MHz bandwidth; when the length is 36.6mm吋, the VSWR is less than 1.6 in the 10MHz bandwidth, which is ideal. . Preferably, the helical structure 11 has a helical length of 20 mm to 40 mm, and more preferably, the helical structure 11 has a helical length of 29 mm. For example, if the width of the main unit is 42mm, the distance between the feed point and the ground point is about 9mm, and the feed point is 4mm away from the spiral structure. Preferably, the distance between the feeding point and the receiving point is 8 mm_10 mm. The spiral helical structure 11 provided by the present invention is similar to the conventional Helix antenna in the prior art and will not be described in detail herein.

Referring to Figures 3 through 4, Figure 3 is a radiation pattern of an embodiment of the present invention; and Figure 4 is an impedance graph of an embodiment of the present invention. As can be seen from Fig. 3, the maximum gain of the antenna provided by the present invention is Odbi, and its pattern reflects its performance to the conventional omnidirectional antenna. Preferably, a matching circuit can be added to the circuit or a spiral structure can be used to increase its bandwidth in the ultra high frequency band (UHF).

[29] Since the size of the antenna and the host add up to half of the operating wavelength, the inverted-F antenna provided by the present invention can greatly shorten the antenna length for application to a variety of terminal communication devices, such as mobile phones, walkie-talkies, and the like. It can realize the wireless appearance of the communication device. In addition to reducing the size of the antenna, the invention also utilizes the resonance characteristics of the spiral structure, thereby realizing the antenna of the lower frequency band to be built into the host, making the communication device more convenient to carry and more beautiful in appearance; meanwhile, the antenna has the size. Small, high gain, wide bandwidth, good consistency, low cost, etc.

[30] The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and is in the spirit of the present invention. Any modifications, equivalent substitutions or improvements made within the principles are intended to be included within the scope of the present invention.

Claims

Claim

An improved inverted-F antenna comprising: a first conductor portion (1) facing a circuit board, a ground conductor portion (2) connected to the first conductor and electrically connected to a ground point of the circuit board, and the first A feed conductor portion (3) having conductors connected and electrically connected to a feed point of the circuit board, characterized in that the tail portion of the first conductor portion (1) is provided as a spiral structure (11).

The improved inverted-F antenna according to claim 1, wherein said first conductor portion (1) is parallel to the circuit board, and said ground conductor portion (2) and said feed conductor portion (3) are both vertical In the circuit board, the spiral structure (11) is located on one side of the feed conductor portion (3). The improved inverted-F antenna according to claim 1, characterized in that the distance between the end of the spiral structure (11) near the feed conductor portion and the feed conductor portion (3) is larger than the spiral structure

(11) The pitch of the turns.

The improved inverted-F antenna according to claim 3, characterized in that the distance between the end of the spiral structure (11) adjacent to the feed conductor portion and the feed conductor portion (3) is a spiral structure (11) ) The pitch of the turns is twice.

The improved inverted-F antenna according to any one of claims 1 to 4, characterized in that the diameter of the turns of the spiral structure (11) is 4.5 mm - 6 mm.

The improved inverted-F antenna according to any one of claims 1 to 4, characterized in that the distance between the feeding point and the grounding point is 8 mm - 10 mm.

The improved inverted-F antenna according to any one of claims 1 to 4, characterized in that the distance between the first conductor portion (1) and the circuit board is 10 mm - 15 mm.

The improved inverted-F antenna according to any one of claims 1 to 4, characterized in that the spiral structure (11) has a spiral length of 20 - 40 mm.

The improved inverted-F antenna according to claim 8, characterized in that the spiral structure (11) has a spiral length of 29 mm.

A wireless communication device, comprising an inverted F antenna and a motherboard (4) for transmitting a communication signal to at least the outside world or receiving a communication signal from the outside, wherein the inverted F antenna comprises: a first conductor facing the circuit board a portion (1), a ground conductor portion (2) connected to the first conductor and electrically connected to a ground point of the circuit board, and a feeding point connected to the first conductor and electrically connected to the circuit board The tail portion of the first conductor portion (1) of the feed conductor portion is provided as a spiral structure (11).