阅读说明：本技术 一种超宽带高增益Vivaldi天线 (Ultra-wideband high-gain Vivaldi antenna ) 是由 张凯悦 燕有杰 蒋廷勇 王彬文 刘启龙 成真伯 王殿喜 于 2021-10-19 设计创作，主要内容包括：本发明涉及天线技术领域,具体涉及一种超宽带高增益Vivaldi天线。包括介质基板、辐射部分、馈电部分；辐射部分包括第一辐射体、第二辐射体和第三辐射体第一辐射体的内指数槽线与第二辐射体的外指数槽线构成V型槽线,第三辐射体的内指数槽线与第二辐射体的外指数槽线构成V型槽线,从而形成改进型的双V型槽线；馈电部分包括阻抗渐变微带结构和T型功率分配器；第一辐射体和第三辐射体上有开槽,所述开槽为系列矩形槽缝,各矩形槽缝的宽度和间隔相等,长度线性减小。本发明在高频增益损失较小的情况下明显改善了Vivaldi天线在低频段的增益。(The invention relates to the technical field of antennas, in particular to an ultra-wideband high-gain Vivaldi antenna. Comprises a dielectric substrate, a radiation part and a power feeding part; the radiation part comprises a first radiator, a second radiator and a third radiator, wherein the inner index slot line of the first radiator and the outer index slot line of the second radiator form a V-shaped slot line, and the inner index slot line of the third radiator and the outer index slot line of the second radiator form a V-shaped slot line, so that an improved double-V-shaped slot line is formed; the feed part comprises an impedance gradual change microstrip structure and a T-shaped power divider; the first radiator and the third radiator are provided with grooves, the grooves are series of rectangular slots, the width and the interval of each rectangular slot are equal, and the length is linearly reduced. The invention obviously improves the gain of the Vivaldi antenna in a low frequency band under the condition of small high-frequency gain loss.)

1. An ultra-wideband high-gain Vivaldi antenna is characterized by comprising a dielectric substrate, a radiation part and a feed part;

the dielectric substrate comprises a ground plane on the back side and a feed plane on the front side;

the radiation part comprises a first radiation body, a second radiation body and a third radiation body; the first radiator and the third radiator are symmetrically arranged on the feed surface of the dielectric substrate, the second radiator is arranged on the ground surface of the dielectric substrate, and the first radiator and the third radiator both comprise two slot lines, an inner index slot line and an outer index slot line; the inner index slot line of the first radiator and the outer index slot line of the second radiator form a V-shaped slot line, and the inner index slot line of the third radiator and the outer index slot line of the second radiator form a V-shaped slot line, so that an improved double-V-shaped slot line is formed; the improved double-V-shaped groove lines are exponential increasing curves and are symmetrical up and down, so that the cross polarization level of the antenna is reduced, and the gain of the antenna is enhanced;

the first radiator and the third radiator are provided with grooves, the grooves are series of rectangular slots, the width and the interval of each rectangular slot are equal, the length is linearly reduced, the slot loading is adopted to improve the current distribution, the current path is increased, and the low-frequency gain is enhanced;

the feed part comprises an impedance gradual change microstrip structure and a T-shaped power divider, and is arranged on the dielectric substrate and connected with the radiation part; the impedance gradual change microstrip structure is arranged on the ground plane, and the gradual change slot line is a quarter ellipse; the T-shaped power divider comprises an input end, two first impedance conversion lines, two second impedance conversion lines and four output ends, wherein the input end is arranged on the feeding surface, is connected with one first impedance conversion line and one second impedance conversion line which are arranged on the feeding surface, and is respectively connected with the first radiator and the third radiator through the two output ends; the first impedance conversion line and the second impedance conversion line of the ground plane are connected with the impedance gradual change microstrip structure and then are connected with the second radiator through two output ends; the two first impedance conversion lines are connected through the through hole, so that interaction of a positive electrode and a negative electrode is realized, and normal work of the antenna is ensured.

2. An ultra-wideband high-gain Vivaldi antenna according to claim 1, wherein the four outputs of said T-shaped power divider are each chamfered at the bend.

3. The ultra-wideband high-gain Vivaldi antenna as claimed in claim 2, wherein the junction of the first impedance transformation line and the second impedance transformation line of the T-shaped power splitter is V-cut.

4. The ultra-wideband high-gain Vivaldi antenna as claimed in claim 2, wherein the effect of vias on the length of the feed path can be balanced by offsetting the input axis of said T-shaped power divider to the via side by half the thickness of the dielectric substrate.

Technical Field

The invention relates to the technical field of antennas, in particular to an ultra-wideband high-gain Vivaldi antenna.

Background

The ultra-wideband technology has the advantages of insensitive channel fading, low power spectral density of transmitted signals, low interception capability, low system complexity, low energy, capability of providing positioning accuracy of several centimeters and the like, and thus becomes one of popular technologies in the field of wireless communication. The Vivaldi antenna has the advantages of wide bandwidth, simple structure, easiness in processing, low cost and the like, and has important application in the fields of radar, tumor detection, microwave imaging and the like. In a microwave imaging system, in order to meet the requirements of detection depth and precision, the gain of an ultra-wideband antenna needs to be improved.

To address this problem, lengthening the dielectric substrate is a common idea for increasing the antenna gain, but this approach leads to an increase in the size of the antenna. An article, "antenna impedance information with ENZ and high-reactivity index property for high-gain video antenna design", published by researchers such as G.K. Paney and M.K. Meshram, proposes to use a metamaterial to achieve the purpose of high gain, but this method also brings problems and causes the antenna impedance bandwidth to be narrower. In addition, the high gain of the conventional Vivaldi antenna is often reflected in a higher frequency band, and the problem of overlarge gain difference between the high frequency band and the low frequency band exists.

Disclosure of Invention

The invention aims to provide an ultra-wideband high-gain Vivaldi antenna, which solves the technical problem that the Vivaldi antenna realizes higher radiation gain on the basis of widening low-frequency bandwidth.

In order to achieve the purpose, the technical scheme of the invention is as follows:

an ultra-wideband high-gain Vivaldi antenna comprises a dielectric substrate, a radiation part and a feed part;

the dielectric substrate comprises a ground plane on the back side and a feed plane on the front side;

the radiation part comprises a first radiation body, a second radiation body and a third radiation body; the first radiator and the third radiator are symmetrically arranged on the feed surface of the dielectric substrate, the second radiator is arranged on the ground surface of the dielectric substrate, and the first radiator and the third radiator both comprise two slot lines, an inner index slot line and an outer index slot line; the inner index slot line of the first radiator and the outer index slot line of the second radiator form a V-shaped slot line, and the inner index slot line of the third radiator and the outer index slot line of the second radiator form a V-shaped slot line, so that an improved double-V-shaped slot line is formed; the improved double-V-shaped groove lines are exponential increasing curves and are symmetrical up and down, so that the cross polarization level of the antenna is reduced, and the gain of the antenna is enhanced; the first radiator and the third radiator are provided with grooves, the grooves are series of rectangular slots, the width and the interval of each rectangular slot are equal, the length is linearly reduced, the slot loading is used for improving the current distribution, increasing the current path and enhancing the low-frequency gain;

the feed part comprises an impedance gradual change microstrip structure and a T-shaped power divider, and is arranged on the dielectric substrate and connected with the radiation part; the impedance gradual change microstrip structure is arranged on the ground plane, and the gradual change slot line is a quarter ellipse; the T-shaped power divider comprises an input end, two first impedance conversion lines, two second impedance conversion lines and four output ends, wherein the input end is arranged on the feeding surface, is connected with one first impedance conversion line and one second impedance conversion line which are arranged on the feeding surface, and is respectively connected with the first radiator and the third radiator through the two output ends; the first impedance conversion line and the second impedance conversion line of the ground plane are connected with the impedance gradual change microstrip structure and then are connected with the second radiator through two output ends; the two first impedance conversion lines are connected through the through hole, so that interaction of a positive electrode and a negative electrode is realized, and normal work of the antenna is ensured;

furthermore, the bent part of each output end of the four output ends of the T-shaped power divider is processed by a chamfer angle, so that the impedance matching of the connecting part is improved.

Furthermore, the connection position of the first impedance conversion line and the second impedance conversion line of the T-shaped power divider is subjected to V-shaped corner cutting treatment, so that the impedance matching of the connection position is improved.

Furthermore, the input end axis of the T-shaped power divider deviates 0.5mm towards the via hole side, so that the influence of the via hole on the length of the feed path can be balanced.

The invention has the following beneficial effects:

the Vivaldi antenna research based on the via holes and the gradual change rectangular slots has the following beneficial effects:

1. the ultra-wideband high-gain Vivaldi antenna provided by the invention has the advantages that S11< -10dB and the gain of 5-12.2dBi are within the bandwidth of 0.7-10GHz, the gain is greater than 7.1dBi when the frequency is greater than 0.8GHz, the gain is greater than 10dBi within the frequency band of 1.7-10GHz, the ultra-wideband and the high gain are realized, and the gain difference within the high-low frequency bandwidth is reduced.

2. The invention provides an ultra-wideband high-gain Vivaldi antenna, and provides a method for combining an improved double V-shaped slot line with loading of a rectangular gradually-changed slot, so that the gain of the Vivaldi antenna in a low-frequency band is obviously improved under the condition of small high-frequency gain loss.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a diagram of the dimensions of the front patch structure of the present invention;

FIG. 3 is a dimensional diagram of a reverse patch structure of the present invention;

FIG. 4 is a diagram illustrating a simulation result of return loss characteristics according to the present invention;

FIG. 5 is a diagram illustrating the gain simulation result of the present invention.

Detailed Description

The invention will be described and explained with reference to the drawings.

An ultra-wideband high-gain Vivaldi antenna as shown in fig. 1 includes a first radiator 1, a second radiator 2, a third radiator 3, a dielectric substrate 4 and a feed structure 5.

The first radiator 1 and the third radiator 3 are printed on the feed surface of the dielectric substrate 4, the upper and the lower parts of the first radiator and the third radiator are in a symmetrical structure, and the second radiator 2 is printed on the ground surface of the dielectric substrate 4. The slot lines of the first radiator 1 and the third radiator 3 comprise an outer index slot line 11 and an inner index slot line 12, a series of rectangular slots 13 are formed, and the slot line of the second radiator 2 comprises an outer index slot line 31 and an inner index slot line 32. The feed structure 5 is an impedance gradual change microstrip structure and a T-shaped power divider, and comprises a microstrip feed line 51 printed on the feed surface of the dielectric substrate 4 and a perfect circle gradual change balun structure 53 printed on the ground surface, wherein two output ends of the microstrip feed line 51 are respectively connected with the first radiator and the third radiator, two output ends of the perfect circle gradual change balun structure 53 are respectively connected with the second radiator, and the connection positions are processed by adopting corner cuts so as to optimize impedance matching.

The dielectric plate had a length of 319.9mm, a width of 200.0mm, a thickness of 1.0mm, a relative dielectric constant of 2.65 and a dielectric loss tangent of 0.001.

The expression general formula of the index gradual change slot line of the antenna is as follows:

y＝C1i*e^ai*x+C2i+ws/2

wherein C1i, ai and C2i are coefficients. The coefficients of the index gradual change slotlines 11 are respectively C11, a1 and C21, the coefficients of the inner index slotlines 12 are respectively C12, a2 and C22, the coefficients of the outer index slotlines 31 are respectively C13, a3 and C23, the coefficients of the inner index slotlines 32 are respectively C14, a4 and C24, wherein C11-C12-C13-1.

The inner index slot line 12 and the outer index slot line 31 form an inclined V-shaped slot, the other V-shaped slot is in a symmetrical position below the inclined V-shaped slot, the inner index slot line and the outer index slot line form an improved double V-shaped slot, the cross polarization of the antenna is reduced, the gain of the antenna is improved, and the inner index slot line 32 is used for optimizing the current distribution of the second radiator.

The series of rectangular slots 13 are used to improve the current distribution and the gain of the antenna. As shown in fig. 2, the lengths of the 23 rectangular slots are in an arithmetic sequence, wherein the longest slot length is dy1, the shortest slot length is dy2, the slot width is dx, the distance between the slots is dg, and the rightmost slot is away from the right edge ds of the substrate.

As shown in fig. 2, the axis of the input end of the T-shaped power divider deviates 0.5mm to the via side, the deviation is half of the thickness of the dielectric substrate, so as to balance the influence of the via on the length of the feed path, and the connection between the input end and the impedance transformation line is subjected to V-shaped corner cutting. The width of the input end feeder line is wf, the width of the impedance conversion line is wb, the width of the V-shaped corner cut is aw, and the depth is ad.

As shown in fig. 3, the feed line of the second radiator is composed of a perfect circular tapered balun and an impedance conversion line. The width of the right-circular gradually-changed balun structure is w1, the radius of the circular arc is 38.70mm, the axis of the right-circular gradually-changed balun structure deviates 0.5mm towards the side of the through hole, and the deviation is half of the thickness of the dielectric substrate.

The impedance conversion line on one side of the T-shaped power divider is connected through the two cylindrical through holes 52, so that the normal synthesis of the electric field between the double V-shaped grooves is realized, and the normal work of the antenna is ensured. Wherein the diameter of the bottom surface of the cylinder is 0.4mm, and the height is 1 mm. The middle of the via hole structure is isolated by a Z-shaped slot with the width of 0.4 mm.

After the optimization of the CST software, the specific parameters of the antenna are finally determined as table 1.

TABLE 1

The present example was modeled in the electromagnetic simulation software CST. Fig. 4 is a diagram illustrating a simulation result of return loss characteristics. According to the standing wave ratio simulation result, the S11< -10dB of the antenna is obtained in the frequency range of 0.7-10 GHz.

Fig. 5 is a diagram showing the results of the gain simulation of the present example. In the frequency range of 0.7-10GHz, the antenna gain is 5-12dBi, when the frequency is greater than 0.8GHz, the gain is greater than 7.1dBi, and in the frequency range of 1.7-10GHz, the gain is greater than 10dBi, and the antenna gain is relatively stable in the whole working frequency range.