KR20070017109A - A dual band diversity wlan antenna system for laptop computers, printers and similar devices - Google Patents

Abstract

The present invention relates to a dual band antenna device having a dielectric substrate 6. A microstrip transmission line 4 is disposed on a first surface of the dielectric substrate, and a ground plate 7 is disposed on a second surface opposite to the first surface, and a first microstrip transmission line 4 is disposed. The dielectric pellet 5 is mounted on the surface. On the first side of the dielectric substrate, an inverted L-shaped flat antenna (PILA) component 1 is mounted in two pieces, the PILA component 1 contacting and extending over the surface of the dielectric pellet 5. The arm part 2 and the 2nd arm part 3 are provided. The first arm portion and the second arm portion are different from each other in contact with the surface of the dielectric pellet. The antenna device of the present invention is configured to operate well in the frequency band of 2.4 GHz and the frequency band of 5.9 GHz.

Description

A dual band diversity WLAN antenna system for use in devices such as laptop computers, printers, printers, printers and simulators

The present invention relates to an IEEE802.11a / b / g wireless LAN (LAN) having a dual-band radiator coupled to a microstrip transmission line by shaped ceramic pellets of molded ceramic. A novel antenna which operates in the frequency band used. The antenna device of the present invention is designed to be mounted on the display portion of a laptop computer, or can be used in a device that communicates with a computer such as a printer.

With the introduction of wireless LAN connections, there is a need for compact, inexpensive antennas that operate in the 2.4-2.5 GHz and 4.9-5.9 GHz frequency bands. Such antennas are typically mounted on laptop computers, PDAs, and the like, and may also be mounted on printers, scanners, or other peripheral devices.

An important characteristic of these antennas is that they must be highly efficient and have radiation patterns that are as omnidirectional as possible even when mounted in the device. There is a trade-off between the problem of making it smaller and lowering the manufacturing cost. Most antennas will be connected directly to a very small coaxial cable, and the antenna design must implement appropriate attachment measures to control the cable placement precisely enough to ensure good repeatability of the input match. .

According to a first aspect of the present invention, there is provided a dual band antenna device having a dielectric substrate, wherein a microstrip transmission line is disposed on a first side of the dielectric substrate, and a ground plate is disposed on a second side opposite to the first side, Dielectric pellets are mounted on a first side of the microstrip transmission line, and on the first side of the dielectric substrate, two inverted L-shaped flat antenna (PILA) components are mounted in two, and the PILA component is mounted on the surface of the dielectric pellets. A first arm portion and a second arm portion extending in contact therewith, wherein the first arm portion and the second arm portion have different areas in contact with the surface of the dielectric pellet, and the PILA component is electrically connected to the ground plate. It is characterized by providing a band antenna device.

The dielectric substrate may be in the form of a printed circuit board (PCB) having a metallized (eg copper) ground plane. Particularly preferred dielectric substrates are Duroid® PCBs.

The dielectric pellets are preferably made of a ceramic material having a high dielectric constant, for example, having a relative dielectric constant of at least six or more.

The dielectric pellets are preferably long-length rectangles with an almost flat top surface (ie, the surface of the pellet at the end from the first side of the dielectric surface). In particular, it is preferable to form the bridge structure so as to connect with the microstrip transmission line only at its end.

The bifurcated PILA is disposed almost in line with the long length dielectric pellets, the first arm portion of the PILA being in contact with the surface extending across almost the entire longitudinal direction of the top surface of the dielectric pellets, and the second arm of the PILA The portions are shorter in length than the first arm portion and contact in less area than the exposed surface of the dielectric pellets in contact with the first arm portion. The ends of the PILA at the ends from the first and second arm portions may be connected to the ground plate by conductive pins passing through the dielectric substrate.

Compared to the conventional dielectric resonator antenna (DRA) structure, when ceramic pellets (resonators) are fed at a single point (for example, by a flob or slot feeder), the ceramic pellets of the present invention are connected to a microstrip transmission line. Feed along the length. Ceramic pellets do not radiate on their own, but serve as a mainspinning structure by acting as a dielectric load on the arm portion of the PILA.

For example, in the low frequency band of 2.4 GHz, the longer first arm of the PILA's arm portion functions as the main radiator and is excited by an electromagnetic field at the edge of the ceramic pellets near the end of the first arm portion.

For example, in the low frequency band of 5.54 GHz, the shorter second arm of the PILA's arm portion functions as the main radiator and is excited by an electromagnetic field at the edge of the ceramic pellets near the end of the second arm portion.

Nevertheless, the entire ceramic pellet can excite the PILA stronger or weaker, depending on the frequency and the specific design element.

By exciting the two arm portions of the PILA differently, the present invention provides a novel dual band hybrid antenna.

In another embodiment, the portion of the dielectric substrate directly underneath the ceramic pellets may be removed so that the dielectric pellets float out of the PILA on the ground plate and may omit the microstrip transmission line. In this embodiment, the dielectric pellets are fed directly by a coaxial cable having internal elements soldered or otherwise connected to the dielectric pellets and external elements connected to ground.

Accordingly, in another aspect, the present invention provides a dual band antenna device having a dielectric substrate, wherein a microstrip transmission line is disposed on a first side of the dielectric substrate, a ground plate is disposed on a second side opposite to the first side, On the first surface of the dielectric substrate, two inverted L-shaped flat antennas (PILA) parts are mounted in two, the PILA parts having a first arm part and a second arm part electrically connected, and the first arm part and the first arm part. 2 the arm portion is connected to the surface of the dielectric pellet, the dielectric substrate includes a hole disposed below the dielectric pellet, the dielectric pellet is connected to the coaxial feed line, the first arm portion and the second arm portion of the PILA component The area in contact with the surface of the pellets is different and the PILA component provides a dual band antenna device electrically connected to the ground plane.

BRIEF DESCRIPTION OF DRAWINGS To aid the understanding of the present invention and to show how the invention works, it will be described in detail below with reference to the accompanying drawings.

1 shows a preferred embodiment of the present invention.

FIG. 2 is a diagram showing an electromagnetic field configuration of the antenna shown in FIG. 1 in the band of 2.4 GHz. FIG.

FIG. 3 shows the electromagnetic field configuration of the antenna shown in FIG. 1 in the band of 5.5 GHz. FIG.

4 is a coordinate diagram showing measured values of return loss of the antenna shown in FIG.

FIG. 5 shows the coordinates of the isolation between the pair of antennas shown in FIG. 1. FIG.

In the embodiment shown in FIG. 1, the antenna comprises three main components.

Radiating element (1): This element is a quarter-wavelength, grounded patch of narrow shape, with separate radiators 2, 3 for each frequency band ( grounded patch).

Microstrip Transmission Lines 4: Radiating elements 1, 2, 3 are excited from microstrip feed lines 4 entering the open circuit end of the antenna structure. This microstrip feed line 4 uses a matched microstrip / coaxial transition scheme to allow feeding from an ultra-small coaxial cable (1.2 mm in diameter) (not shown) to the antenna.

Ceramic pellets (ceramic pellets 5): A radiating element 1 is mounted on top of the dielectric pellets 5 (? R = 6 in this embodiment) made of molded ceramics, reducing its physical length, To strengthen the coupling between the radiating element 1 and the microstrip feed line 4.

The radiating element 1, the microstrip transmission line 4, and the dielectric pellets 5 made of ceramic are all mounted on one side of the insulating substrate 6, and the insulating substrate is preferably made of Duroid®. . On the opposite side of the insulating substrate 6, a conductive ground plate 7 is provided.

The leg 8 of the radiating element 1 is shorted to the ground plate 7 through the insulating substrate 6 by conductive connection.

Although the dielectric pellets 5 made of ceramic do not function as a dielectric resonator antenna (DRA), the operation of the antenna structure depends largely on the presence of the dielectric pellets made of ceramic for reasons other than simply loading a dielectric. Done. Thus, an antenna structure having dielectric pellets made of ceramic is also referred to as a hybrid ceramic antenna.

The radiating element 1 is a PIFA (inverted F-shape) with a fixed feed point connected into the patch or in intimate capacitive coupling to the patch, in typical use for use of small patch antennas. Flat panel antennas). In the opposite case, the radiating element 1 corresponds to a PILA (inverted L-shaped flat antenna) and does not have a direct feed point. Instead, the radiating element is excited by an electromagnetic field in the dielectric pellets 5 of ceramic having a relatively long length, and is powered by the microstrip transmission line 4. The electromagnetic field in the dielectric pellets 5 made of ceramic is generated by displacement current. This arrangement provides a number of additional parameters such as the shape, dimensions and relative permittivity of the dielectric pellets 5 in ceramic and their relative positions to the microstrip transmission line 4 and the radiating element 1. Optimizing these parameters allows the designer to substantially select the performance of the antenna, as can be seen from the embodiments of the present invention.

The microstrip transmission line is arranged at the open end of the PILA 1. In a typical feed line, it will be difficult to power the antenna because its impedance is very high.

PILA 1 is divided into two arm portions 2, 3 having different lengths. The dielectric pellet 5 made of a long length of ceramic functions as a power feeding portion, effectively driving the two arm portions 2 and 3 of the PILA 1, each operating at an appropriate frequency.

Simulation result:

Early antennas were performed using HFSS, an Ansoft® 3D electromagnetic simulator. Computer simulation results show that good return loss is obtained in the desired frequency band. The simulation results also show that the two parts 2, 3 of the radiating element 1 operate effectively and independently, and that the size, shape and permittivity of the dielectric pellets 5 made of ceramic are optimized. FIG. 2 shows the electric field distribution expected in the middle of the low frequency band of 2.4 GHz, and the electric field distribution shown in FIG. 2 is the strongest at the end of the long arm part 3 of the radiating element 1. FIG. 3 shows the electric field distribution expected in the middle of the high frequency band of 5.5 GHz, the electric field distribution shown in FIG. 3 being the strongest at the end of the arm part 2 on the short side of the radiating element 1.

Measurement result:

4 shows the result of measuring the reflection efficiency on the input side of the completed antenna and the feed cable. The small ripple of the measured values, caused by mismatches at the measuring points, is a common problem when working with micro cables at high frequencies.

It can be seen that this design is configured to provide wider bandwidth at 5 GHz rather than 2.5 GHz, corresponding to the requirements of the antenna. In practical applications, compensating the connector discontinuity in the connected device can reduce input mismatch and corresponding ripple, and achieve a return loss of 10 dB across both bands.

In order to investigate the isolation performance, a pair of antennas was mounted on the top of the display with a 75 mm spacing of the laptop application, between the antennas. As can be seen from FIG. 5, the isolation between the antennas is approximately 20 dB in the low frequency band (when antennas are closer together electrically) and 40 dB in the high frequency band.

Preferred features of the invention are applicable to all features of the invention and can be used in any possible combination.

The words "comprising", "comprising", and the like, which are used throughout the description and claims of this specification, are not for the purpose of limitation and are not intended to exclude other components, integral parts, parts, accessories, or steps.

Claims (8)

A dual band antenna device having a dielectric substrate, A microstrip transmission line is disposed on a first surface of the dielectric substrate, and a ground plate is disposed on a second surface opposite to the first surface, A dielectric pellet is mounted on the first surface on which the microstrip transmission line is disposed, On the first surface of the dielectric substrate, two inverted L-shaped flat antenna (PILA) components are mounted in two parts, The PILA component has a first arm portion and a second arm portion in contact with and extending over the surface of the dielectric pellets, wherein the first arm portion and the second arm portion are in contact with the surface of the dielectric pellet. Different, And the PILA component is electrically connected to the ground plate. The method of claim 1, And the dielectric pellets are made of a ceramic material having a high dielectric constant. The method according to claim 1 or 2, And wherein said dielectric pellet is made of a long length structure having a substantially flat exposed surface facing each other spaced from a first side of said dielectric substrate. The method of claim 3, wherein And the dielectric pellet is formed as a bridge structure having a first feed portion and a second feed portion in contact with the microstrip transmission line. The method according to claim 3 or 4, The bifurcated PILA is disposed almost in line with the long length dielectric pellets, wherein the first arm portion of the PILA contacts the exposed surface while extending across substantially the entire longitudinal direction of the exposed surface of the dielectric pellets. And wherein the second arm portion of the PILA is shorter in length than the first arm portion and contacts in less area than the exposed surface of the dielectric pellets in contact with the first arm portion. The method according to any one of claims 1 to 5, The dual band antenna device is configured to operate in the first frequency band of 2.4GHz to 2.5GHz and the second frequency band of 4.9GHz to 5.9GHz. A dual band antenna device having a dielectric substrate, A microstrip transmission line is disposed on a first surface of the dielectric substrate, and a ground plate is disposed on a second surface opposite to the first surface, On the first surface of the dielectric substrate, two inverted L-shaped flat antenna (PILA) components are mounted in two parts, The PILA component has a first arm portion and a second arm portion electrically connected to each other. A surface of a dielectric pellet is connected to the first arm portion and the second arm portion, The dielectric substrate comprises a hole formed under the dielectric pellets, The dielectric pellets are connected to a coaxial feed line, The first arm portion and the second arm portion of the PILA part are different from each other in contact with the surface of the dielectric pellet, And the PILA component is electrically connected to the ground plate. Dual band antenna device as disclosed or shown in the accompanying drawings with reference to the accompanying drawings.

Images