CN104638355B - A kind of ultra-wideband antenna of the double trap characteristics of band - Google Patents

Abstract

The invention discloses a kind of ultra-wideband antennas of the double trap characteristics of band, including：It is disposed on the substrate the Radiating dipole and the first and second capacitive loops load split ring on surface；It is etched with trap slot on the Radiating dipole, is fed by feed line, the first and second capacitive loops load split ring is separately positioned on the both sides of feed line.The present invention loads split ring by etched a trap slot on radiating dipole patch respectively and using a pair of of capacitive loop at feeder line, effectively inhibits the interference of WiMAX (3.3 3.8GHz) systems and WLAN (5.15 5.825GHz) system.

Description

A UWB Antenna with Dual Notch Characteristics

technical field

The invention relates to the communication field, in particular to an ultra-wideband antenna with double notch characteristics.

Background technique

In the past decade or so, due to the outstanding advantages of Ultra Wide Band (UWB, Ultra Wide Band) antennas, such as high data rate and low power consumption, it has aroused widespread interest in the industry. However, the main challenges faced by the design of the UWB antenna include electromagnetic interference (EMI, Electromagnetic Interference) and radiation stability. Electromagnetic interference mainly comes from WiMAX (Worldwide Interoperability for Microwave Access) (3.3-3.8GHz) and wireless local area network (WLAN, Wireless Local Area Networks) (5.155.825GHz) systems, these system frequency bands occupy the US Federal Communications Commission ( FCC, Federal Communications Commission) allocated to UWB frequency band (3.1-10.6GHz). In order to mitigate the electromagnetic (EMI) interference caused by WiMAX and WLAN systems, researchers have proposed many UWB antenna designs with notch characteristics. However, due to the omnidirectional nature of these antennas, antennas of this type are generally low gain.

On the other hand, modern wireless communication systems have higher and higher requirements for safety and efficiency. Therefore, antennas with good directivity and high gain are urgently required. To meet these stringent requirements, researchers have designed some directional ultra-wideband antennas with high gain. By using electromagnetic dipoles (ME) combined with reflector structures, high gain, stable radiation patterns, and broadband width. In addition, there is also a UWB antenna using a box-shaped reflector, a directional band notch and high gain characteristics, however, this solution only achieves a band notch, and due to the addition of stacked parasitic patches (SSP) Increase antenna height.

To sum up, ordinary ultra-wideband notch antennas are usually omnidirectional and low-gain, which cannot meet the safety and efficiency requirements; electromagnetic dipole ultra-wideband antennas with reflectors have high-gain and directional characteristics, but they cannot achieve Notch, does not meet anti-interference requirements.

Contents of the invention

The technical problem to be solved by the present invention is to provide an ultra-wideband antenna with dual notch characteristics, which is used to solve the electromagnetic interference problem of the ultra-wideband antenna in the prior art.

In order to solve the above technical problems, the present invention provides an ultra-wideband antenna with dual notch characteristics, including:

The radiation dipole arranged on the upper surface of the substrate, and the first and second capacitive loop load split rings; the radiation dipole is etched with a trap, which is fed by a feeder line, and the first and second The capacitive loop load split rings are respectively arranged on both sides of the feeder line.

Further, the notch groove is used to control the frequency band of the notch, the longer the total length of the notch groove, the lower the frequency of the notch frequency band; the wider the width of the notch groove, the wider the notch frequency band.

further,

Among them, L _always is the total length of the notch groove, C is the speed of light, f _WiMAX is the WiMAX notch frequency, and ε _eff is the effective dielectric constant.

Further, the radiation dipole is elliptical, the trap groove is a U-shaped groove, and the length L ₁ of the closed end of the U-shaped groove, the height L ₂ of the U-shaped groove and the groove width W ₁ of the U-shaped groove are respectively in the range of 15.5 mm≤L ₁ ≤2*R _major ; 2mm≤L ₂ ≤2*R _minor ;0.1mm≤W ₁ ≤2mm; where, R _major is the radius of the major axis of the elliptical radiation dipole, and R _minor is the radius of the elliptical radiation dipole Major axis radius.

Further, the first and second capacitive loop load split rings are respectively used to control the frequency bands of different notches, and have different side lengths, the longer the side lengths of the first and second capacitive loop load split rings are , the lower the notch frequency band is; the wider the ring width of the first and second capacitive loop load split rings, the wider the notch frequency band.

further,

Wherein, L1 is the side length of the load split ring of the first _capacitive loop, C is the speed of light, f _WLAN is the WLAN notch frequency, and ε _eff is the effective dielectric constant.

Further, the distance G ₁ between the load split ring of the first capacitive loop and the feeder line ranges from _{0.1mm≤G1≤2mm} ;

The range of the distance G ₂ between the second capacitive loop load split ring and the feeder line is _{0.1mm≤G2≤2mm} .

Further, the antenna also includes:

For the arc-shaped floor arranged on the lower surface of the substrate, the range of the arc height H _arc of the arc-shaped floor is _1mm≤H arc≤6mm.

Further, the antenna also includes:

A copper reflector, the copper reflector is horn-shaped or box-shaped; the open end of the copper reflector constitutes the upper surface of the antenna, and the closed end constitutes the lower surface of the antenna, and the substrate is fixed on the lower surface of the antenna by plastic screws surface.

Further, the value of the distance H _ground between the lower surface of the antenna and the lower surface of the substrate is,

Among them, C is the speed of light, ε _eff is the effective permittivity, and f _center is the center frequency of the UWB antenna.

The beneficial effects of the present invention are as follows: the present invention effectively suppresses the WiMAX system and the WLAN system by etching a notch groove on the radiation dipole patch and adopting a pair of capacitive loop load split rings near the feeder line. interference.

Description of drawings

Fig. 1 is a three-dimensional schematic diagram of an ultra-wideband antenna with dual notch characteristics in an embodiment of the present invention;

Figure 2a is a top view of an ultra-wideband antenna with dual notch characteristics in an embodiment of the present invention;

Figure 2b is an enlarged schematic view of a large capacitive loop load split ring in an embodiment of the present invention;

Figure 2c is an enlarged schematic view of a small capacitive loop load split ring in an embodiment of the present invention;

Figure 2d is an enlarged schematic view of a curved floor in an embodiment of the present invention;

Fig. 3 is a side view of an ultra-wideband antenna with dual notch characteristics in an embodiment of the present invention;

Figure 4a, Figure 4b, and Figure 4c are the vector current distribution diagrams of the U-shaped groove and the capacitive loop load split ring in the 3.5GHz, 5.3GHz and 5.6GHz frequency bands respectively in the embodiment of the present invention;

Figure 4d is a schematic diagram of the current intensity of the U-shaped groove and the capacitive loop load split ring in different channel segments in the embodiment of the present invention;

Fig. 5 is a schematic diagram of standing wave ratio and gain of a kind of ultra-wideband antenna with dual notch characteristics in simulating and testing an embodiment of the present invention;

Fig. 6 a and Fig. 6 b are the radiation patterns of a kind of ultra-wideband antenna with double notch characteristic in the embodiment of the present invention simulated and measured in the 4GHZ frequency band;

Fig. 7a and Fig. 7b are the radiation patterns of an ultra-wideband antenna with double notch characteristics in the simulation and measurement of the embodiment of the present invention in the 7GHZ frequency band;

Fig. 8a and Fig. 8b are simulation and measurement radiation patterns of an ultra-wideband antenna with double notch characteristics in the embodiment of the present invention in the 9GHZ frequency band.

Detailed ways

In order to solve the problem of electromagnetic interference of the ultra-wideband antenna in the prior art, the present invention provides an ultra-wideband antenna with dual notch characteristics. The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

As shown in Figure 1, the antenna includes a copper reflector 1, a substrate 2, a radiating dipole 4, a feeder 6, a pair of capacitive load split rings, and a curved floor 10; wherein the copper reflector 1 is horn-shaped and adopts Made of copper material, the open end of the copper reflector 1 forms the upper surface of the antenna, and the closed end forms the lower surface of the antenna, and the area of the upper surface is larger than the area of the lower surface. The substrate 2 adopts a square Rogers 5880 (Rogers 5880) substrate, and plastic screw fixing holes 3 are set near the four included corners of the substrate 2, and the plastic screws pass through the plastic screw fixing holes 3 to fix the substrate 2 on the lower surface of the antenna. A curved floor 10 is printed on the lower surface of the substrate 2 (the side of the substrate 2 facing the lower surface of the antenna). The curved floor 10 is used as a ground plane. Arc, that is to say, an arc-shaped floor 10 is set between the substrate 2 and the lower surface of the antenna; an elliptical radiation dipole 4 is printed on one end of the upper surface of the substrate 2 (the side facing away from the lower surface) , the end of the radiation dipole 4 on the substrate 2 is called the top of the substrate 2, and the other end is called the bottom of the substrate 2; the radiation dipole 4 is fed by the feed line 6; and the radiation dipole 4 A U-shaped groove 5 is etched on the top, the open end of the U-shaped groove 5 faces the top of the substrate 2 , and the closed end faces the feeder 6 . One end of the feeder 6 is connected to the radiation dipole 4, and the other end is connected to the SMA connector 7, and a pair of capacitive loop load split rings with different sizes are arranged on the substrate 2 on both sides of the feeder 6, that is to say The side lengths of the two capacitive loop load split rings are different or the side lengths and ring widths of each side of the two capacitive loop load split rings are different. The two capacitive loop load split rings are respectively the first capacitive loop load split ring 8 and the second capacitive loop load split ring 9, and the openings of the two capacitive loop load split rings are all facing away from Feed line 6.

As shown in Figures 2a, 2b, 2c and 2d, the substrate 2 has a thickness (H _sub ) of 0.787mm and a dielectric constant of 2.2. The major axis (R _major ) and minor axis (R _minor ) radii of the elliptical radiation dipole 4 are 19 mm and 9.8 mm, respectively.

The U-shaped slot 5 is mainly used to avoid electromagnetic interference caused by WiMAX (3.3-3.8GHz). The U-shaped slot can also use the E-shaped slot, which is collectively called the notch slot. The total length of the notch slot controls the frequency band of the WiMax notch. The longer the total length, the lower the frequency of the notch frequency band; the slot width of the notch slot W ₁ controls the width of the notch, the wider the groove width of W1, the wider the notch frequency band. vice versa. For example, when the wave notch is a U-shaped groove, the _total length L of the wave notch = L ₁ +2*L ₂ ; generally speaking, it should conform to the formula: Where C is the speed of light, f _WiMAX is the WiMAX notch frequency, and ε _eff is the effective dielectric constant. The value range is: 15.5mm≤L ₁ ≤2*R _major ; 2mm≤L ₂ ≤2*R _minor ; 0.1mm≤W ₁ ≤2mm, the groove width (W ₁ ) of the U-shaped groove 5 is 0.4mm, U The length (L ₁ ) of the closed end of the U-shaped groove 5 is 25.5 mm, and the height (L ₂ ) of the U-shaped groove 5 is 4.9 mm. The feeder line 6 has a width (W _line ) of 2 mm and a characteristic impedance of 50Ω. The distance (H ₁ ) between the bottom end of the base plate and the closed end of the U-shaped groove was 26.3 mm.

Due to the wide bandwidth of the WLAN (5.15-5.825GHz) notch band, it is divided into two continuous notch bands, respectively 5.15-5.35GHz and 5.35-5.825GHz, correspondingly, these two capacitive loops are specially designed Load split rings (ie: the first and second capacitive loops load split rings) to generate and control two continuous notch frequency bands, thereby suppressing electromagnetic interference caused by WLAN (5.15-5.825 GHz). The overall shape of the first/second capacitive split ring can be square or semicircular or triangular. The characteristic is that there is a parallel capacitor port at the opening, and the coupling strip near the feeder line can be parallel to the feeder line; the opening with a large size Take the side length (L ₁ ) of the ring (the first capacitive split ring) as an example, L ₁ = L ₃ +2*(L ₄ +L ₅ +L ₆ )+6*W ₂ , which should meet: which is where C is the speed of light, f _WLAN is the WLAN notch frequency, and ε _eff is the effective permittivity. That is, the side length L ₃ +2*(L ₄ +L ₅ +L ₆ )+6*W ₂ controls the frequency band of the WLAN notch, the longer the total length, the lower the frequency of the notch band; W ₂ mainly controls the width of the notch , the wider W ₂ is, the wider the notch frequency band is, and the wider W ₂ is, the higher the notch frequency band is. And vice versa. In addition, the distance G ₁ /G ₂ between the large/small capacitive split ring and the feeder is also important, the closer the coupling current is, the better the coupling current effect is, and the general value range is: 0.1mm≤G ₁ ≤2mm; 0.1mm≤G ₂ ≤2mm; the ring widths (W ₂ , W ₃ ) of the two capacitive loop load split rings are both 0.4mm, and the distances (G ₁ , G ₂ ) from the feeder 6 are both 0.1 mm.

In addition, in order to achieve good impedance matching, the ground plane is printed on the back of the substrate and is designed to be arc-shaped. The arc-shaped height H _arc on the back of the substrate can mainly adjust the impedance matching and expand the bandwidth of the UWB antenna. The value range should generally be : 1mm≤H _arc ≤6mm.

In order to obtain good directivity and high gain, an optimized reflector is used. The horn transmitter is mainly used to increase the gain and improve the directional pattern. Its shape can be a horn or a box. Among them, the distance H _ground between the lower surface of the horn transmitter (the lower surface of the antenna) and the substrate is a key parameter, and the value should satisfy Among them, C is the speed of light, ε _eff is the effective dielectric constant f _center is the center frequency of the ultra-wideband antenna. The general value range of other parameters is: 77mm≤L _uref ≤121mm; 77mm≤L _lref ≤121mm, L _lref ≤L _uref , 8mm≤H _ref ≤60mm. Its height (H _ref ) is preferably 22 mm. The distance (H _ground ) between the substrate and the bottom of the reflector is 10mm, which is very important for the effect of the gain. The dimensions of the upper surface (L _uref ×L _uref ) and the lower surface (L _lref ×L _lref ) of the antenna are 99×99mm2 and 77×77mm2, respectively. The detailed dimensions of the antenna are preferably as shown in Table 1.

Table 1

In the table, L ₁ and L ₂ represent the length of the closed end of the U-shaped slot 5 and the height of the U-shaped slot 5 respectively; L ₃ represents the coupling band parallel to the feeder line of the first capacitive loop load split ring 8, mainly The current of the feeder is coupled to the first capacitive ring, L ₄ represents the coupling band perpendicular to the feeder of the first capacitive loop load split ring 8, and L ₆ represents the vertical portion of the opening of the first capacitive split ring, It is mainly inductive, L ₅ represents the horizontal part at the opening of the first capacitive split ring, which is mainly capacitive; L ₇ represents the coupling band of the second capacitive loop load split ring 9 parallel to the feeder line, which mainly connects the feeder line The current coupled to the second capacitive ring, L ₈ represents the coupling band of the second capacitive loop load split ring 9 perpendicular to the feeder line, L ₉ represents the vertical part of the opening of the second capacitive split ring, mainly in the form of Inductive, L ₁₀ represents the horizontal part at the opening of the second capacitive split ring, which is mainly capacitive; L ₁₁ represents the length of the curved floor 10, W ₄ represents the width of the curved floor 10, and _Harc represents the height of the curved floor 10 Arc height; L _sub and W _sub respectively represent the length and width of the substrate 2, H _sub represents the thickness of the substrate 2, H _ground represents the height of the substrate 2 from the lower surface of the antenna; L _line represents the length of the feeder 6, W _line Indicates the width of the feeder line 6; H ₂ and H ₃ respectively represent the distance between the bottom end of the small capacitive split ring (the second capacitive split ring) and the bottom end of the substrate and the distance between the bottom end of the large capacitive split ring (the first capacitive split ring ) between the bottom and the bottom of the substrate.

Figure 4a, Figure 4b, Figure 4c and Figure 4d show the vector current distribution of U-shaped slot and capacitive loop load split ring at different frequency bands of 3.5GHz, 5.3GHz and 5.6GHz. These frequencies are the center frequencies of WiMAX and WLAN (high and low bands), respectively. It can be seen from the figure that the U-shaped groove and a pair of capacitive loop load split rings have the strongest current in the above three frequency bands, while the current in other places is relatively small, that is, the U-shaped groove and a pair of capacitive loop loads The split ring plays a leading role in the above frequency bands respectively, and is stronger than the electric dipole current, thus realizing the notch effect.

The standing wave ratio, gain, and radiation pattern of the ultra-wideband antenna with double notch characteristics in the embodiment of the present invention are measured by an Agilent E5071C network analyzer and a SATIMO antenna measurement system.

As shown in Figure 5, the measured curve is in good agreement with the simulated curve. The measured impedance bandwidth is 3-10.8GHz, and the notch frequency bands are 3.2-3.9GHz and 5.1-5.9GHz (SWR≤2). The peak VSWR ratios of the lower and upper notched bands of WiMAX and WLAN are 15.5, 7.5 and 9.1, respectively. Corresponding to the above notched bands, the measured gains drop to 2.7, 7.4 and 6.7 dBi, respectively. In other words, the antenna can suppress WiMAX and WLAN interference, and the effect is obvious. In the remaining frequency bands, the measured gain fluctuates between 9.5dBi-12.5dBi, including the required UWB frequency band, which is relatively stable, high enough and directional, and suitable for UWB applications. As shown in Fig. 6a, Fig. 6b, Fig. 7a, Fig. 7b, Fig. 8a and Fig. 8b, the antenna exhibits good directional radiation characteristics. In the operating frequency range, substantially symmetrical radiation patterns are achieved in the E- and H-planes. In addition, the cross-polarization levels measured on both the E- and H-planes are substantially lower than -22dB, while the front-to-back ratios are both greater than 16dB. Due to the influence of the second harmonic in the high frequency band, the E-plane of the main polarization is slightly divided into three parts.

The ultra-wideband antenna with double notch characteristics of the embodiment of the present invention has low cross polarization, substantially symmetrical E-plane and H-plane electrical characteristics, and can simultaneously meet the requirements of safety and efficiency and double notch frequency bands. Suppress WiMAX (3.3-3.8GHz) systems and WLAN (5.15-5.825GHz) systems by etching a U-shaped groove on the radiating dipole patch and adopting a pair of capacitive loop load split rings near the feed line, respectively interference; the arc design of the ground plane under the substrate provides excellent impedance matching; the optimized horn-shaped copper reflector meets the requirements of safety and efficiency, and obtains good directivity and high gain characteristics. According to the test results, the ultra-wideband antenna with dual notch characteristics of the embodiment of the present invention has these features, is suitable for directional ultra-wideband communication, and meets the requirements of security, orientation and high data transmission rate.

Although preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, and therefore, the scope of the present invention should not be limited to the above-described embodiments.

Claims (7)

1. A kind of ultra-broadband antenna with double notch wave characteristic, it is characterized in that, comprising: The radiation dipole arranged on the upper surface of the substrate, the first and second capacitive loops load the split ring and the copper reflector; the radiation dipole is etched with a wave notch, which is fed by the feeder line, and the first and the second capacitive loop load split ring are respectively arranged on both sides of the feeder; the notch groove is used to control the frequency band of the notch, the longer the total length of the notch groove, the lower the frequency of the notch frequency band; the notch groove The wider the slot width, the wider the notch frequency band; the first and second capacitive loop load split rings are respectively used to control different notch frequency bands, and have different side lengths; The copper reflector is trumpet-shaped; the open end of the copper reflector constitutes the upper surface of the antenna, the closed end constitutes the lower surface of the antenna, and the substrate is fixed on the lower surface of the antenna by plastic screws; The value of the distance _Hground between the lower surface of the copper reflector and the lower surface of the substrate is, Among them, C is the speed of light, ε _eff is the effective permittivity, and f _center is the center frequency of the UWB antenna. 2. The antenna of claim 1, comprising: Among them, L _always is the total length of the notch groove, C is the speed of light, f _WiMAX is the WiMAX notch frequency, and ε _eff is the effective dielectric constant. 3. The antenna according to any one of claims 1-2, comprising: The radiation dipole is elliptical, the trap groove is U-shaped groove, the length L ₁ of the closed end of the U-shaped groove, the height L ₂ of the U-shaped groove and the groove width W ₁ of the U-shaped groove are respectively in the range of 15.5mm≤ L ₁ ≤2*R _major ; 2mm≤L ₂ ≤2*R _minor ;0.1mm≤W ₁ ≤2mm; where, R _major is the radius of the major axis of the elliptical radiation dipole, and R _minor is the minor axis of the elliptical radiation dipole radius. 4. The antenna of claim 1, comprising: The longer the side length of the first and second capacitive loop load split rings, the lower the notch frequency band; the wider the ring width of the first and second capacitive loop load split rings, the wider the notch frequency band. 5. The antenna of claim 4, comprising: Among them, L _{capacitance 1} is the side length of the first capacitive loop load split ring, C is the speed of light, f _WLAN is the WLAN notch frequency, ε _eff is the effective dielectric constant; W ₂ is the first capacitive loop load opening The ring width of the ring. 6. The antenna of claim 1, comprising: The range of the distance G ₁ between the load split ring of the first capacitive loop and the feeder line is _{0.1mm≤G1≤2mm} ; The range of the distance G ₂ between the second capacitive loop load split ring and the feeder line is _{0.1mm≤G2≤2mm} . 7. The antenna according to claim 1, wherein the antenna further comprises: For the arc-shaped floor arranged on the lower surface of the substrate, the range of the arc height H _arc of the arc-shaped floor is _1mm≤H arc≤6mm.