KR20030017128A - Dual- or multi-frequency planar inverted f-antenna - Google Patents

Abstract

PURPOSE: A dual or multi-frequency planar inverted F-antenna is provided to allow the antenna to be suitably arranged in a wide variety of internal installation spaces of communication equipment. CONSTITUTION: A dual or multi-frequency planar inverted F-antenna comprises a metal surface(31) matched to the size and shape of the internal installation space of a communication equipment and arranged on the top of a ground surface(30). The metal surface has an open slot(32) forming a common closed end(38) and a common open end(39), to thereby divide the metal surface into a longer portion(33) and a shorter portion(34). Positions of a short point(35) and a supply point(36) are adjusted in accordance with a predetermined frequency, to thereby obtain a predetermined impedance match between the short point and the supply point of the metal surface. The length of the longer portion between the short point to the open end of the open slot, and the length between the short point to the end of the shorter portion are determined by the dual and multi-resonance frequency interacting with the deformed and curved open slot.

Description

Dual or multi-frequency plane inverted F-antenna {DUAL- OR MULTI-FREQUENCY PLANAR INVERTED F-ANTENNA}

The present invention relates to dual or multi-frequency planar F-antennas and, more particularly, to planar antennas suitable for installation in different interior spaces of various equipment of dual or multi-frequency.

A spiral coil wound around a metal wire is an antenna. Any of the diameter of the coil of this type of spiral antenna or the pitch between the material or coil ring or the total length of the coil will affect the set function. However, a disadvantage of this conventional spiral antenna is that it protrudes three-dimensionally from the equipment. In communications equipment requiring modern miniaturized or built-in antennas (such as mobile phones or portable computers), conventional three-dimensional antennas are certainly not desirable.

Accordingly, various miniaturized planar microstrip antennas have been gradually researched and developed. Initially, however, microstrip antennas, such as those disclosed in US Pat. Nos. 3,921,177 and 3,810,183, typically consisted of thin metal sheets of circular or rectangular shape. Dielectric material is filled between the antenna and ground. Generally speaking, this kind of microstrip antenna may only be suitable for narrower frequency bandwidths. However, U.S. Patent No. 07/695686 provides a polygonal spiral microstrip antenna that is an improvement of the initial microstrip antenna. Its frequency bandwidth is close to that of a typical spiral antenna with a constant impedance. However, a drawback of this type of microstrip antenna is that it is not suitable for modern portable communication equipment because the diameter of the antenna must be very large in order to adapt to low frequencies.

Among the embodiments that can be applied to modern planar antennas, a relatively more noteworthy one is planar inverted F-antenna (PIFA) class. As shown in FIG. 1, the structure of this planar inverted F-antenna includes a metal wire 11 provided on the ground plane 10, and a shorting point 12 is provided at one end of the metal wire 11 and supplied. A point 13 is provided near the shorting point 12 and the feed point 13 is connected to a feed-in axis 14. In this way, a predetermined single frequency antenna is formed. This initial form of planar inverted F-antenna can be developed to obtain a planar inverted F-antenna as shown in FIG. 2. Basically, the planar inverted F-antenna is associated with a metal surface 15 and ground plane 100, a shorting point 120, a supply point 130 and a feed-in shaft 140 of a predetermined area. Includes parts.

“Dual-Frequency PIFA” on page 1451 of “IEEE”, published in October 1997, combines two separate blocks of different sizes into a rectangular shape or by providing open slots with two mutually right angles on a rectangular metal surface. It is described that certain dual frequency PIFAs can be formed. The problem, however, is that mobile phones with different forms of different brands include slightly different operating frequencies and various internal installation spaces for the antenna. Clearly, the techniques mentioned in the above document do not completely solve the problem of installing these dual or multi-frequency PIFAs in different brands of mobile phones.

It is an object of the present invention to provide a dual or multi-frequency PIFA. The device can be matched to various interior installation spaces of communication equipment and becomes a suitable built-in planar dual or multifrequency PIFA.

1 is a perspective view of a conventional single frequency inverted F-antenna;

2 is a perspective view of a conventional single frequency planar inverted F-antenna;

3 is a perspective view of the basic structure of the present invention;

4 is a perspective view of a possible embodiment of the present invention;

5 is a plan view of FIG. 4;

6 is an experimental diagram of the embodiment of FIGS. 4 and 5; And

7 to 10 are experimental diagrams of the electromagnetic radiation fields of the embodiments of the present invention.

In order to achieve the above object, the metal surface on the top of the ground plane of the present invention is divided into long and short portions of different sizes by the deformed and curved open slots, and the shorting point and the supply point can be adjusted appropriately. The length from the short to the end of the short part and the length of the long part from the short to the open end of the open slot are determined by their resonant frequency.

The novelty and other features of the present invention will become apparent upon reading the detailed description of its preferred embodiments in conjunction with the accompanying drawings.

First, referring to FIG. 3, according to the PIFA theory described above, the metal surface 31 may be installed on the ground plane 30 of the present invention. The open slot 32 of the metal surface 31 divides the metal surface into a long portion 33 and a short portion 34. The shorting point 35, feed point 36 and feed-in shaft 37 of the metal surface 31 are selected individually. The open slot 32 has a common closed end 38 and an open end 39 connecting the long part 33 and the short part 34.

Basically, the lengths L ₁ and L _{2 of the} long part 33 and the short part 34 are both λ / 4 of their resonant frequency (such as 900 MHz and 1800 MHz), respectively, and the 50 Ω impedance match is the supply point. By adjusting the position of 36 and the shorting point 35. The widths W ₂ and W _{1 of the} long portion 33 and the short portion 34 are factors that determine the gain of the antenna, respectively.

For example, when installed inside a mobile phone, different inventions provide different interior spaces and the width of the space is generally less than the length of the long part 33, so that the invention is shown in FIGS. 4 and 5. Possible embodiments as shown are provided.

4 and 5, the metal surface 31 of the present invention fits well with the area and shape of the installation environment, and the embodiment in which the edge portions 311 and 312 are cut out as shown is an interior of the mobile telephone. It can be installed to avoid the elements. The deformed and curved open slot 32 constitutes a short portion 34 as the inner zone and a long portion 33 as the outer zone. The open slot 32 makes the closed end 38 fixed in the proper position of the metal face 31 and the open end 39 is open to one side of the metal face 31. In this structure, a movement and adjustment test to obtain the position of the short point 35 and the supply point 36 can be performed.

The most important feature of the invention is the length from the short point 35 to the open end 39 of the long part 33 of the outer zone and the end point 320 of the short part 34 of the inner zone at the short point 35. The length up to is determined by λ / 4 of the double or the resonant frequency. That is, irrespective of the shape of the metal surface 31 according to various installation positions, a dual or multi-frequency PIFA suitable for the interior of communication equipment can be obtained by the deformed and curved open slot 32.

The height between the metal plane 31 and the ground plane 30 of the PIFA is preferably 0.04λ and should not be smaller than 0.04λ in order to avoid narrower bandwidth.

In the dual frequency PIFA test of the above-described structure of the present invention as shown in FIG. 6, the standing wave ratio (VSWR) for the frequency 880 MHz (point 1) is 2.415, and the standing wave ratio for the frequency 960 MHz (point 2) is 3.33. The standing wave ratio for the frequency to 1710 MHz (point 3) is 3.161 and the standing wave ratio for 1880 MHz (point 4) is 3.102. In the built-in type, standing wave ratios between 2.415 and 3.33 are very ideal.

For the electromagnetic radiation-field of the present invention as shown in Figures 7-10, the maximum antenna gains in the E-plane and H-plane at 925 MHz are 0.7 and -2.15 dBi, respectively, and the maximum antenna at 1800 MHz. The gain is 1.64 and 2.29 dBi, respectively. The present invention is certainly feasible.

Thus, this type of planar antenna of the present invention may be suitable for various frequencies and internal installation spaces of various brands. Due to this fact, the present invention has industrial value.

Claims (3)

The metal face of the antenna, which matches the size and shape of the internal installation space of the equipment, is installed on top of the ground plane, and the open slots provided on the metal face form a common closed end and an open end to extend the metal face. Divided into parts and short parts; A predetermined impedance match between the short point and the supply point of the metal surface is obtained by adjusting the positions of the short point and the supply point according to a predetermined frequency; The length of the elongated portion from the shorting point to the open end of the open slot and the length from the shorting point to the end point of the short portion are at double and pore resonant frequencies interacting with the deformed and curved open slot. Dual or multi-frequency planar inverted F-antenna, characterized in that determined by. The method of claim 1, A dual or multi-frequency planar inverted F-antenna, wherein the height between the planar inverted F-antenna and the ground plane is ≥0.04λ. The method of claim 1, Wherein the lengths of the long and short portions are determined by λ / 4 of the double or multi-resonant frequency.