Low-frequency improved antenna structure

Abstract

The invention provides a low-frequency improved antenna structure which comprises a substrate, an antenna circuit is arranged on the front face of the substrate, an antenna ground is arranged on the back face of the substrate, an antenna unit is arranged on the front face side of the first edge of the substrate, and a low-frequency lifting branch knot is arranged on the back face side of the second edge of the substrate. The first edge and the second edge are a group of opposite sides of the substrate; the feed point supporting foot of the antenna unit is connected with the feed point of the antenna circuit, and the grounding supporting foot of the antenna unit and the low-frequency lifting branch knot are both connected with the antenna ground. According to the low-frequency improved antenna structure, the low-frequency lifting branch knot is arranged on one side of the antenna ground of the other edge, opposite to the antenna unit, of the substrate to form low-frequency waves with new frequency, and the problems that the antenna unit is narrow in low-frequency bandwidth and low in efficiency when the size of the substrate is limited are solved.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a low-frequency improved antenna structure. Background Art

[0002] In order to meet the requirements of some scenarios, mobile communication products usually need to control the size within a smaller range, and the antennas of small-sized products generally use built-in antenna technology. As the size becomes smaller, the length of the motherboard will also become smaller. According to the antenna principle, the motherboard length can only be well stimulated when it is a quarter of the wavelength of the antenna frequency. However, a small-sized motherboard cannot reach a quarter of the wavelength of the low frequency, so it cannot stimulate radiation well, resulting in low efficiency at low frequencies. Existing antenna technology generally meets the requirements of different low-frequency bands through pifa antenna + switch combination debugging, such as Figure 1 As shown, although the prior art can achieve different low frequencies through debugging, since the length of the mainboard does not reach a quarter wavelength of the required frequency, the low-frequency bandwidth of the prior solution is narrow and the radiation efficiency is low.

[0003] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0004] The present invention provides a low-frequency improved antenna structure, aiming to solve the technical problems mentioned in the background art existing in the antenna structure of the prior art.

[0005] The technical solution of the present invention is as follows:

[0006] A low-frequency improved antenna structure includes a substrate, an antenna circuit is arranged on the front side of the substrate, an antenna ground is arranged on the back side of the substrate, an antenna unit is arranged on the front side of the first edge of the substrate, and a low-frequency lifting branch is arranged on the back side of the second edge of the substrate, wherein the first edge and the second edge are a group of opposite sides of the substrate; the feeding point leg of the antenna unit is connected to the feeding point of the antenna circuit, and the grounding leg of the antenna unit and the low-frequency lifting branch are both connected to the antenna ground.

[0007] In an optional embodiment of the present invention, the low-frequency boosting branch is also connected to a frequency modulation switching circuit, the frequency modulation switching circuit includes a radio frequency switch chip, the ANT pin of the radio frequency switch chip is electrically connected to the low-frequency boosting branch, each RF pin of the radio frequency switch chip is connected to a passive component, and all of the passive components are connected in parallel and grounded.

[0008] In an optional embodiment of the present invention, the passive element includes one or more of a capacitor, a resistor and an inductor.

[0009] In an optional implementation manner of the present invention, the low-frequency boosting branch is further connected to an electrostatic discharge circuit, and the electrostatic discharge circuit is provided with an inductor and is grounded.

[0010] In an optional implementation manner of the present invention, if the passive element is a resistor, the resistance value of the resistor is zero.

[0011] In an optional embodiment of the present invention, the antenna unit is a PIFA antenna, the length direction of the radiation surface of the PIFA antenna is parallel to the first edge of the substrate, the feeding point of the antenna circuit is arranged at the first corner of the front side of the substrate, and the feeding point leg and the grounding leg of the PIFA antenna are both arranged on the corresponding sides of the first corner;

[0012] The low-frequency lifting branch is rod-shaped, the length direction of the low-frequency lifting branch is parallel to the second edge of the substrate, and the connection point between the low-frequency lifting branch and the antenna ground is arranged at the second corner of the back side of the substrate, wherein the first corner and the second corner are a set of diagonals of the substrate.

[0013] In an optional implementation manner of the present invention, the electrical length of the low-frequency boosting branch is greater than 1%-5% of a quarter wavelength of the low frequency of the antenna unit.

[0014] In an optional implementation manner of the present invention, the feed point support pin and the ground support pin of the pifa antenna are arranged side by side and spaced apart on the outer side of the pifa antenna in the length direction.

[0015] In an optional implementation manner of the present invention, the distance between the radiation surface of the antenna unit and the front surface of the substrate and the distance between the low-frequency lifting branch and the back surface of the substrate are both 0.5-1.5 cm.

[0016] In an optional implementation manner of the present invention, the antenna unit and the low-frequency boost branch are made of materials including copper, aluminum and steel.

[0017] Beneficial effects are as follows: the present invention provides a low-frequency improved antenna structure, comprising a substrate, an antenna circuit is arranged on the front of the substrate, an antenna ground is arranged on the back of the substrate, an antenna unit is arranged on the front side of the first edge of the substrate, and a low-frequency lifting branch is arranged on the back side of the second edge of the substrate, wherein the first edge and the second edge are a set of opposite sides of the substrate; the feeding point leg of the antenna unit is connected to the feeding point of the antenna circuit, and the grounding leg of the antenna unit and the low-frequency lifting branch are both connected to the antenna ground. The low-frequency improved antenna structure of the present invention arranges a low-frequency lifting branch on the antenna ground side of the other edge of the substrate opposite to the antenna unit to form a low-frequency wave of a new frequency, which solves the problem of narrow low-frequency bandwidth and low efficiency of the antenna unit when the size of the substrate is limited. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of an existing mainboard antenna structure of the present invention.

[0019] Figure 2 It is a structural schematic diagram of a low-frequency improved antenna structure of the present invention.

[0020] Figure 3 The figure is a schematic structural diagram of a frequency modulation switch circuit of the present invention.

[0021] Figure 4 The figure is a comparison diagram of the low-frequency waveforms of the existing antenna structure and the antenna structure of the present invention.

[0022] Figure 5 The figure is a comparison diagram of the efficiency of the existing antenna structure and the antenna structure of the present invention.

[0023] The reference numerals in the figures are as follows:

[0024] 10-substrate; 20-antenna unit; 30-low-frequency boost branch; 40-feed point support; 50-ground support; 60-RF switch chip; 70-passive components. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0026] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] Reference throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, when the phrases "in one embodiment" or "in some embodiments" appear in various places throughout the specification, not all references are to the same embodiment. Furthermore, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner.

[0029] See also Figure 2 The present invention provides a low-frequency improved antenna structure, including a substrate 10, wherein an antenna circuit is disposed on the front side (the upper surface is shown in the figure), an antenna ground is disposed on the back side of the substrate 10, an antenna unit 20 is disposed on the front side of the first edge of the substrate 10, and a low-frequency boosting branch 30 is disposed on the back side of the second edge of the substrate 10, wherein the first edge and the second edge are a set of opposite sides of the substrate 10, the feed point leg 40 of the antenna unit 20 is connected to the feed point of the antenna circuit, and the grounding leg 50 of the antenna unit 20 and the low-frequency boosting branch 30 are both connected to the antenna ground. In the present invention, the antenna circuit is used to drive the antenna unit 20 to transmit a signal, and the low-frequency boosting branch 30 is used to enable the antenna unit 20 to form a new low-frequency wave, and the new low-frequency wave acts together with the original low-frequency wave of the antenna unit 20, thereby improving the low-frequency bandwidth and efficiency of the antenna unit 20.

[0030] See also Figure 3 In an optional embodiment of the present invention, the low-frequency boosting branch 30 is also connected to a frequency modulation switch circuit, and the frequency modulation switch circuit includes a radio frequency switch chip 60, and the ANT pin of the radio frequency switch chip 60 is electrically connected to the low-frequency boosting branch 30. Each RF pin of the radio frequency switch chip 60 is connected to a passive component 70, and all of the passive components 70 are connected in parallel and grounded. The passive components include one or more of capacitors, resistors, and inductors. In the present invention, the radio frequency switch chip 60 and the passive component 70 can change the electrical and physical length of the low-frequency boosting branch 30, so that the low-frequency boosting branch 30 emits a low frequency of the desired design frequency. Each RF pin can be connected to one or more passive components 70. When multiple passive components 70 are connected, multiple passive components 70 are connected in series. If the passive component uses a resistor, the resistance value of the selected resistor is zero. The present invention can change the electrical physical length of the low-frequency boosting branch through capacitance or inductance and 0Ω resistance to make the frequency reach the frequency we need. Similarly, the frequency of the antenna body needs to be lower than the frequency of the boosting low-frequency branch, so as to achieve the purpose of improving the low-frequency bandwidth and efficiency.

[0031] In an optional embodiment of the present invention, the RF switch chip 60 can specifically use a RF switch chip of model MXD8544A, and the RF switch chip 60 includes 1 ANT pin, 4 RF pins, 1 VDD pin, 1 GND pin and 3 V pins, and the 4 RF pins are all connected to 1 inductor, and the 4 RF pins are grounded together after being connected to the inductor. The ANT pin is connected to a low-frequency boost branch, and the V pin and VDD pin of the RF switch chip 60 are used for input signals to control the on and off of the RF pin so as to enable the low-frequency boost branch to send different frequencies. In another optional embodiment of the present invention, the low-frequency boost branch is also connected to an electrostatic discharge circuit, and the electrostatic discharge circuit is provided with an inductor and grounded.

[0032] See also Figure 2 In an optional embodiment of the present invention, the antenna unit 20 may be a pifa antenna, the radiation surface (rectangle) of the pifa antenna is parallel to the first edge of the substrate 10 in the length direction (more specifically, the outer side of the radiation surface is aligned with the first edge of the substrate 10), the feeding point of the antenna circuit is arranged at the first corner of the front side of the substrate 10, and the feeding point leg and the grounding leg of the pifa antenna are both arranged on the corresponding side of the first corner; the feeding point leg of the pifa antenna is connected to the feeding point of the antenna circuit, and the pifa antenna passes through the substrate 10 and is connected to the antenna ground on the back side of the substrate 10. In an optional embodiment of the present invention, the feeding point leg and the grounding leg of the pifa antenna are arranged side by side and spaced apart on the outer side of the pifa antenna in the length direction to facilitate the connection of the feeding point leg and the grounding leg of the pifa antenna.

[0033] See also Figure 2 In an optional embodiment of the present invention, the low-frequency lifting branch 30 is rod-shaped, the length direction of the low-frequency lifting branch 30 is parallel to the second edge of the substrate 10, the connection point between the low-frequency lifting branch 30 and the antenna ground is set at the second corner of the back of the substrate 10, the low-frequency lifting branch 30 is connected to the connection point of the antenna ground, and the low-frequency lifting branch 30 and its connecting pin form an L shape, wherein the first corner and the second corner are a set of diagonal corners of the substrate 10. In an optional embodiment of the present invention, the electrical length of the low-frequency lifting branch 30 is greater than 1%-5% of the quarter wavelength of the low frequency of the antenna unit 20, so that the low-frequency lifting branch 30 forms a new low-frequency waveform.

[0034] The invention adds a low-frequency branch node at the antenna foot, and its electrical length is slightly greater than a quarter wavelength of the low frequency, so that a new waveform is generated near the frequency of the original low-frequency branch node. The waveform frequencies of the two branches are similar, thus generating a "W"-shaped waveform. Figure 4The low-frequency waveform comparison diagram of the existing antenna structure and the antenna structure of the present invention (taking a mobile phone watch as an example and based on an arm model test), from Figure 4 It can be seen from the above that the bandwidth of the "W"-shaped waveform formed by adding and enhancing the low-frequency branch is much wider and deeper than the bandwidth of the single "V"-shaped waveform in the original scheme. Figure 5 This is an efficiency comparison diagram between the existing antenna structure and the antenna structure of the present invention. It can be seen from the figure that the efficiency and return loss diagrams are basically consistent. The antenna structure solution of the present invention has better bandwidth and efficiency at low frequencies.

[0035] In summary, the present invention provides a low-frequency improved antenna structure, including a substrate, an antenna circuit is arranged on the front side of the substrate, an antenna ground is arranged on the back side of the substrate, an antenna unit is arranged on the front side of the first edge of the substrate, and a low-frequency lifting branch is arranged on the back side of the second edge of the substrate, wherein the first edge and the second edge are a set of opposite sides of the substrate; the feeding point leg of the antenna unit is connected to the feeding point of the antenna circuit, and the grounding leg of the antenna unit and the low-frequency lifting branch are both connected to the antenna ground. The low-frequency improved antenna structure of the present invention arranges a low-frequency lifting branch on the antenna ground side of the other edge of the substrate opposite to the antenna unit to form a low-frequency wave of a new frequency, which solves the problem of narrow low-frequency bandwidth and low efficiency of the antenna unit when the size of the substrate is limited.

[0036] Although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A low frequency improved antenna structure, characterized in that: It includes a substrate, an antenna circuit is arranged on the front side of the substrate, an antenna ground is arranged on the back side of the substrate, an antenna unit is arranged on the front side of the first edge of the substrate, and a low-frequency lifting branch is arranged on the back side of the second edge of the substrate, wherein the first edge and the second edge are a group of opposite sides of the substrate; the feeding point leg of the antenna unit is connected to the feeding point of the antenna circuit, and the grounding leg of the antenna unit and the low-frequency lifting branch are both connected to the antenna ground.

2. The low-frequency improved antenna structure according to claim 1, characterized in that: The low-frequency boost branch is also connected to a frequency modulation switch circuit, which includes a radio frequency switch chip. The ANT pin of the radio frequency switch chip is electrically connected to the low-frequency boost branch. Each RF pin of the radio frequency switch chip is connected to a passive component, and all of the passive components are connected in parallel and grounded.

3. The low frequency improved antenna structure according to claim 2, characterized in that: The passive components include one or more of capacitors, resistors and inductors.

4. The low frequency improved antenna structure according to claim 2, characterized in that: The low-frequency boosting branch is also connected to an electrostatic discharge circuit, and an inductor is provided on the electrostatic discharge circuit and is grounded.

5. The low frequency improved antenna structure according to claim 3, characterized in that: If the passive element is a resistor, the resistance of the resistor is zero.

6. The low frequency improved antenna structure according to claim 4, characterized in that: The antenna unit is a pifa antenna, the length direction of the radiation surface of the pifa antenna is parallel to the first edge of the substrate, the feeding point of the antenna circuit is arranged at the first corner of the front side of the substrate, and the feeding point leg and the grounding leg of the pifa antenna are both arranged on the corresponding side of the first corner; The low-frequency lifting branch is rod-shaped, the length direction of the low-frequency lifting branch is parallel to the second edge of the substrate, and the connection point between the low-frequency lifting branch and the antenna ground is arranged at the second corner of the back side of the substrate, wherein the first corner and the second corner are a set of diagonals of the substrate.

7. The low frequency improved antenna structure according to claim 5, characterized in that: The electrical length of the low-frequency boosting branch is greater than 1%-5% of a quarter wavelength of the low frequency of the antenna unit.

8. The low frequency improved antenna structure according to claim 1, characterized in that: The feed point support pin and the ground support pin of the pifa antenna are arranged side by side and at intervals on the outer side of the pifa antenna in the length direction.

9. The low frequency improved antenna structure according to claim 1, characterized in that: The distance between the radiation surface of the antenna unit and the front surface of the substrate and the distance between the low-frequency lifting branch and the back surface of the substrate are both 0.5-1.5 cm.

10. The low-frequency improved antenna structure according to any one of claims 1 to 9, characterized in that: The materials of the antenna unit and the low-frequency boost branch include copper, aluminum and steel.

Images