TWI493788B - Planar antenna - Google Patents

Description

Planar antenna

The present invention relates to an antenna, and more particularly to a planar antenna.

In today's fast-changing world of technology, a variety of lightweight antennas have been developed for use in increasingly lightweight communications products. For example, mobile phones, notebook computers, digital portable assistants, and family room wireless base stations, etc., in addition to the high requirements of electrical characteristics, the lightness of the product is more urgently demanded by consumers. However, how to effectively reduce the size of the antenna and reduce the cost, so that the product has more diverse application areas, it is one of the urgent needs of research and development. Therefore, how to reduce the size of the antenna and make it cost-effective has become one of the goals pursued.

The invention relates to a planar antenna, which has the advantages of low cost and reduced volume.

According to the present invention, a planar antenna is provided, comprising a substrate, a grounding portion and a radiating portion. The substrate has a surface, the ground portion is disposed on the surface of the substrate, and one end of the ground portion is grounded. The radiation portion is disposed on the surface of the substrate, and one end of the radiation portion is electrically connected to the other end of the ground portion, and one end of the radiation portion serves as a feeding point. The radiation portion has a concave The groove and the groove are connected to the feed point.

The above described objects, features, and advantages of the present invention will become more apparent and understood.

The invention provides a planar antenna comprising a substrate, a grounding portion and a radiating portion. The substrate has a surface, the ground portion is disposed on the surface of the substrate, and one end of the ground portion is grounded. The radiation portion is disposed on the surface of the substrate, and one end of the radiation portion is electrically connected to the other end of the ground portion, and one end of the radiation portion serves as a feeding point. The radiating portion has a recess, and the recess is connected to the feed point. An embodiment will be described below.

Please refer to FIG. 1 , which is a schematic diagram of a planar antenna according to an embodiment of the present invention. The planar antenna 10 includes a substrate 30, a radiating portion 50, and a ground portion 70. The substrate 30 has opposing first and second surfaces 302, 304. The radiating portion 50 is disposed on the first surface 302 of the substrate 30. The radiating portion 50 has an end 52 and a recess 54. One end 52 of the radiating portion 50 serves as a feeding point, and the groove 54 of the radiating portion 50 is connected to the feeding point. The grounding portion 70 is disposed on the first surface 302 of the substrate 30, and the grounding portion 70 is electrically connected to the grounding surface 702 disposed on the second surface 304.

Please refer to FIG. 2, which shows a plan view of the planar antenna of FIG. 1. The radiation portion 50 has a long side S1 and a short side S2. The groove 54 of the radiating portion 50 is connected to the feeding point 52, and a part of the groove 54 is It extends along the long side S1 of the radiation portion 50. The grounding portion 70 has a first end 704 and a second end 706. The first end 704 is electrically connected to the ground plane 702, and the second end 706 is connected to the feed point 52.

As shown in Fig. 2, the periphery of the radiating portion 50 is approximately rectangular. The groove 54 of the radiating portion 50 is substantially L-shaped, having a first portion 542, a second portion 544, and an edge length sum L1. The first portion 542 of the groove 54 is second with the groove 54. Portions 544 are connected and substantially perpendicular to each other. The first portion 542 extends along the long side S1 of the radiating portion 50. The second portion 544 extends along the short side S2 of the radiation portion 50. Although the groove 54 of the embodiment is illustrated by an L-shaped structure, the groove 54 may be an annular structure and an arbitrary shape, and may have a plurality of turns, as long as the groove 54 is embedded. The radiation portion 50 and the groove 54 conform to the edge length sum L1 from the feed point 52, which is substantially equal to a quarter wavelength of the radiated wireless signal (L1≒1/4λ, λ represents the wavelength). Further, by changing the sum L1 of the edge length of the groove 54, the magnetic flux distribution of the antenna can be relatively changed to adjust the required radiation frequency.

Further, the substrate 30 has at least one through hole V1, so that the ground portion 70 located at the first surface 302 is electrically connected to the ground plane 702 of the second surface 304 through the through hole V1. The through hole V1 is preferably disposed at the first end 704 of the ground portion 70. The first end 704 of the grounding portion 70 is electrically connected to the ground plane 702 through the through hole V1. In the present embodiment, a through hole V1 is taken as an example, but the present invention is not limited thereto.

The principle of operation of the planar antenna 10 is similar to that of the Plane Inverted F Antenna (PIFA) shown in FIG. Referring to Figures 2 and 3 simultaneously, the endpoint 402 is the feed end, the endpoint 404 is open, and the endpoint 406 is grounded. In the present planar antenna 10, the feed point 52 is preferably used as the feed end, the other end 504 of the radiating portion is open, and the ground portion 70 is grounded. Thus, the radiating portion 50 functions similarly to the first portion 408 of the PIFA of FIG. 3, and the ground portion 70 functions similarly to the second portion 410 of the PIFA of FIG. After the signal is transmitted to the feed point 52 via the transmission line 522, the signal will be radiated through the radiation portion 50.

In the embodiment, the substrate 30 is, for example, a printed circuit board (PCB). The planar antenna 10 can be applied to a wireless local area network (Wireless LAN, WLAN), or the industry standard 802.11b/g for wireless network communication established by The Institute of Electrical and Electronic Engineers (IEEE), Bluetooth. (Bluetooth), etc.

As shown in Fig. 2, the substrate 30 is, for example, a printed circuit board made of glass fiber, having a dielectric constant ε _r of 4.4 and a loss tangent tan δ (Loss tangent) of 0.02.

Please refer to FIG. 4, which is a diagram showing the analog size of the planar antenna of FIG. 1. As shown in Fig. 4, the planar antenna 10 is modeled according to the dimensions indicated in the figure and the characteristic parameters of the substrate (ε _r = 4.4, tan δ = 0.02), and the unit of size is mm (mm).

Please refer to FIG. 5, which illustrates the planar antenna 10 of FIG. The result of the Return Loss simulated as shown in Figure 4. The planar antenna 10 of the present embodiment can be operated from 2.39 GHz to 2.49 GHz with a bandwidth of 100 MHz, depending on the requirement that the return loss needs to be less than -10 dB and the bandwidth needs to be greater than or equal to 100 MHz.

Please refer to FIG. 6 , which shows the result of the maximum gain (Peak Gain) simulated by the planar antenna 10 of FIG. 1 according to the size of FIG. 4 . The peak gain corresponding to the frequency band 2.39 GHz to 2.49 GHz of the planar antenna 10 of this embodiment is between 0.8 dBi and 1.3 dBi.

Please refer to FIG. 7 , which shows the result of the average gain (Average Gain) simulated by the planar antenna 10 of FIG. 1 according to the size of FIG. 4 . According to the specification requirement that the average gain is greater than ~4 dB, it can be seen from FIG. 7 that the average gain corresponding to the band 2.39 GHz to 2.49 GHz of the planar antenna 10 of the present embodiment is between ~0.87 dB and -0.8 dB.

Please refer to FIG. 8 , which illustrates a polarization field pattern 708 on the X-Z plane simulated by the planar antenna 10 of FIG. 1 operating at 2.45 GHz according to the size of FIG. 4 . It can be seen that the planar antenna 10 is characterized by an Omni-directional antenna.

Please refer to FIG. 9 , which is a polarization field pattern 709 simulated on the Y-Z plane simulated by the planar antenna 10 of FIG. 1 operating at 2.45 GHz according to the size of FIG. 4 .

Please refer to FIG. 10, which is a schematic diagram of a planar antenna according to another embodiment of the present invention. The planar antenna 10A includes a substrate 30A, a radiation portion 50A, and a ground portion 70A. Not with the planar antenna 10 of Fig. 1 Similarly, the grounding portion 70A can be grounded by other means, for example, by being connected to the grounding wire 902. As such, the present embodiment does not need to have the ground plane 702 as shown in FIG. Therefore, the planar antenna 10A only needs to be used to one surface 303 of the substrate and can also perform operations similar to PIFA.

As shown in FIG. 11, a schematic diagram of a planar antenna according to still another embodiment of the present invention is shown. The planar antenna 10B includes a substrate 30B, a radiation portion 50B, and a ground portion 70B. Different from the planar antenna 10 of Fig. 1, a portion 1002 of the groove 54B of the radiating portion 50B remote from the feeding point 52A is substantially a ring-shaped structure or even a spiral structure. By having a plurality of turns, the length of the groove 54B can be lengthened to obtain a desired frequency, and the area occupied by the planar antenna 10B can be saved. Portion 1002 of recess 54B may also be arcuate and need not have a turn. It is within the scope of the invention as long as the length of the recess 54B can be adjusted with the frequency of the signal to be radiated.

The planar antenna of the invention has good radiation characteristics, and the length of the groove is adjustable. The invention has the advantages of small volume, low cost and simple fabrication.

In view of the above, the present invention has been disclosed in a preferred embodiment, and is not intended to limit the present invention. A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

10, 10A, 10B‧‧‧ antenna

30, 30A, 30B‧‧‧ substrate

302‧‧‧ first surface

303‧‧‧One of the surfaces of the antenna

304‧‧‧ second surface

402‧‧‧Feeding end

404‧‧‧Open road

406‧‧‧ Grounding

408‧‧‧ first part

410‧‧‧Part II

50‧‧‧ Radiation Department

504‧‧‧The other end of the Radiation Department

52‧‧‧Feeding point

522‧‧‧ transmission line

54‧‧‧ Groove

542‧‧‧ first part

544‧‧‧Part 2

70‧‧‧ Grounding Department

702‧‧‧ ground plane

704‧‧‧ first end

706‧‧‧ second end

Polarization pattern on the X-Z plane of 708‧‧‧

Polarization pattern on the 709‧‧‧Y-Z plane

1002‧‧‧Parts of the groove

FIG. 1 is a schematic diagram of a planar antenna according to an embodiment of the present invention.

Fig. 2 is a plan view showing the planar antenna of Fig. 1.

Figure 3 is a schematic diagram of a planar inverted F-type antenna.

Figure 4 is a diagram showing the analog dimensions of the planar antenna of Figure 1.

Fig. 5 is a graph showing the result of the return loss simulated by the planar antenna of Fig. 1 according to the size of Fig. 4.

Figure 6 is a graph showing the results of the peak gain simulated by the planar antenna of Figure 1 in accordance with the dimensions of Figure 4.

Figure 7 is a graph showing the results of the average gain simulated by the planar antenna of Figure 1 in accordance with the dimensions of Figure 4.

Figure 8 is a diagram showing the polarization field pattern simulated on the X-Z plane when the planar antenna of Figure 1 is operated at 2.45 GHz.

Figure 9 is a diagram showing the polarization field pattern simulated on the Y-Z plane simulated by the planar antenna of Figure 1 operating at 2.45 GHz.

FIG. 10 is a schematic diagram of a planar antenna according to another embodiment of the present invention.

11 is a schematic diagram of a planar antenna according to still another embodiment of the present invention.

10‧‧‧Antenna

30‧‧‧Substrate

302‧‧‧ first surface

304‧‧‧ second surface

50‧‧‧ Radiation Department

52‧‧‧Feeding point

54‧‧‧ Groove

70‧‧‧ Grounding Department

702‧‧‧ ground plane

Claims (6)

A planar antenna comprising: a substrate having a surface; a grounding portion disposed on the surface, one end of the grounding portion being grounded through at least one through hole; a radiating portion disposed on the surface, the radiating portion is coupled to the surface The other end of the grounding portion is electrically connected, the end of the radiating portion is used as a feeding point, and the radiating portion has a groove connected to the feeding point; wherein the radiating portion functions like a flat In the first part of the Plane Inverted F Antenna (PIFA), the grounding portion acts like the second part of the PIFA. The planar antenna of claim 1, wherein the periphery of the radiating portion is substantially rectangular, and the recess extends along one of the long sides of the radiating portion. The planar antenna of claim 1, wherein the length of the edge of the groove from the feed point is substantially equal to a quarter wavelength. The planar antenna of claim 1, wherein the shape of the groove is substantially L-shaped. The planar antenna of claim 4, wherein the periphery of the radiating portion is substantially rectangular, and a portion of the groove connected to the feeding point extends along a long side of the radiating portion . The planar antenna according to claim 1, wherein The groove has a plurality of turns.