The antenna is one of the most important components in wireless communication devices. The main two functions of its wireless communication equipment are energy conversion and directional radiation or receiving functions. Its bandwidth is also a hard indicator, which is directly restrained for the broadband communication system, so the broadband technology of the antenna came into being.
The spiral antenna has occupied an important position in navigation systems and communication systems due to its good round pole performance, broadband bands, and high -oriented. With the development of wireless communication technology, from the 1930s, the use of radio applications above 30MHz to the use of the GHz frequency band above the Second World War, as well as the significant increase in information volume, the speed and quality of information transmission, the broadband Bring an antenna came into being. As a result, this article conducts a broadband band design and simulation analysis of the spiral antenna in the antenna.
The dissertation introduces the basic knowledge of the antenna and related research at home and abroad at home and abroad, and briefly describe the structure and basic parameters of the spiral antenna. The second chapter of the paper is the introduction of the design process of the spiral antenna of the broadband belt, and briefly introduces the simulation software CST. Finally, a micro -band spiral antenna is designed with its performance contrast analysis.
Keywords: antenna; broadband; spiral antenna
Antenna is one of the most important components in wireless communication equipment, its main two functions are energy conversion and directional radiation or receiving function. And its bandwidth is also a hard index, which has a direct constraint on the broadband communication system, so the broadband Technology of the Antenna Arises at the Right Moment.
Spiral antenna plays an important role in navigation system and communication system because of its good circular polarization performance, broadband property and high directional property. With the development of wireless communication technology, from the 1930s, the application frequency of radio in 30MHz to the second world war GHz band above the use, as well as the substantial improvement of information, information transmission speed and quality and other requirements, broadband antenna therefore emerged. Therefore, in this paper, the spiral antenna in the antenna broadband design and simulation analysis.
At the beginning of this paper, the basic knowledge of antenna and the related research of broadband antenna at home and abroad are introduced, and the structure and basic parameters of spiral antenna are briefly described. In the second chapter, the design process of broadband spiral antenna is introduced, and the simulation software CST is briefly introduced, followed by modeling and simulation of the designed broadband spiral antenna, and the performance of the simulation results is analyzed and studied. Finally, a microstrip spiral antenna is designed and compared with its performance Analysis.
Key words: ANTENNA; Wideband Antenna; The Spiral Antenna
Today is an era of information explosion. The information sent and received every day is irreplaceable, and wireless communication plays an irreplaceable role in the transmission of information. Important. The antenna is one of the most important components in the wireless communication system. Its function is to complete the conversion of electrical signals and wave signals and the launch and reception of electromagnetic energy in free space.
The system indicators and size of wireless communication determine the type and physical size of the antenna. Its overall work efficiency and good work quality are restricted by the operating performance of the antenna within a certain range. Therefore Studies have significant scientific significance. With the rapid development of electronic science and technology and communication technology, as one of the important components in the wireless communication system, antenna must have the trend of broadband and integration with the development of technology. Therefore The broadband and integration of the indicators has become the research direction of many communication technicians and scholars.
The spiral antenna has the characteristics of simple design and its wide bandwidth, easy structure, powerful function, rich in application fields, as well as a real input impedance and can produce round polarized light neighborhoods, but its inherent group delay special characteristics , Resulting in color dispersing limits its application scope, if it cannot be used as a pure radar antenna. In 1947, American scientist John D.kraru found the radiation characteristics of the spiral antenna through experiments . There are three modes of three -dimensional spiral antennas, which are the method direction mode, axial mode and cone mode. The spiral antenna has the characteristics of simple broadband, system structure, orientation radiation and rounding. Domain [2-3]. And with the development of science and technology, the superior electrical performance of the spiral antenna is also widely used; the spiral antenna is a “frequency -free antenna”. The relative bandwidth of these antennas can reach 30: 1 high, which means that if the antenna’s The frequency is 1GHz, so the antenna can still work in the frequency band to 30GHz (representing its good performance); so the spiral antenna provides a good design foundation for the broadband design of the antenna. The broadband band spiral antenna comes out, and it has the characteristics of large bandwidth and excellent performance of the spiral antenna. The geometric chart of the spiral antenna is shown in Figure 1.1:
Figure 1.1 Geometric diagram of the spiral antenna
The parameters of the spiral antenna are as follows:
D -spiral diameter
S -vertical distance between spiral rings
C -The length of the pile coil of a circle of spiral coils
C = π*D (1.1)
N -number of spiral coils
H -Height of the Spiral antenna
H = n*s (1.2)
α -snail distance angle
α = TAN^(-1) 〖〖S/C〗 (1.3)
Broadband band spiral antennas are of great significance in many fields such as national defense military, satellite communication, outer space communication, and radio , especially in the era of information creation of information, which has extraordinary significance for its in -depth research and use of multiple fields.
Broadband band spiral antennas at home and abroad at home and abroad
Before the mid -20th century, the bandwidth and application of antenna generally did not exceed 2: 1, and after the mid -20th century, the concept of frequent unrelated antennas in Rumsey in 1957, as well as the corner spiral and the number of planes that appeared later In the cycle structure antenna, people have expanded the bandwidth development of the antenna to 40: 1 and a higher ratio. In the 1970s, Soviet scholar Yulcartov and Ronorf made corresponding research and theoretical analysis of various forms of spiral antennas and proposed the working principle of the spiral antenna.
In the early 21st century, Professor of IEEE FELLOW, Warren Stutzman proposed a new type of six -arm spiral antenna , and this new six -arm antenna is used to maintain the relative distance between the spiral arm through mechanical principles. During the design process, Professor Warren Stutzman, on the basis of fully using the space in the antenna cover, reflects the characteristics of this new six -arm spiral antenna.
In 2019, Liu Lulu of Qingdao University designed a broadband band spiral antenna (Figure 1.2) with a single spiral feeder (Figure 1.2). The measured bandwidth is 38-55MHz.
Figure 1.2 Broadband band spiral antenna model and physical map designed by Liu Lu Road
Gu Aijun of the Chengdu University of Electronic Science and Technology of China designed a cone -to -number spiral antenna that can cover the S to X -band . It has a wider bandwidth, and the width of the 3DB band of antennas can reach 100^0, but its disadvantage is that the height of the antenna is higher and the height exceeds 80mm . The antenna structure is shown in Figure 1.3:
Figure 1.3 The cone pairing spiral antenna model and physical map proposed by Gu Aijun
The research content and thesis arrangement of this article
Based on the theory of the spiral antenna, this article designed a broadband band spiral antenna, and simulated analysis of it and the same micro -band spiral antenna.
The specific content arrangement of the full text is as follows:
Chapter One Introduction. This chapter mainly introduces the research background and research significance of the spiral antenna and its broadband broadband, and briefly describes the existing research results and research directions of this project. At the end of this chapter, the content is briefly described.
Chapter 2, Broadband Band Spiral Aperton Design Scheme. In this chapter, the basic parameters of the broadband band spiral antenna are designed and introduced in detail.
Chapter III, Modeling of Broadband Band Spiral Apertper. In this chapter, the design of the wide -frequency band spiral antenna is made to build simulation on the simulation software CST, and analyzes the results after the simulation, including S parameters, resident wave ratio, bandwidth, direction diagram, gain and impedance matching.
Chapter 4, analysis of broadband and micro -band spiral antenna. In this chapter, a micro -band spiral antenna is designed to compare the two antennas on the basis of Chapter 3, which shows the advantages and disadvantages of the two antennas.
Chapter 5, Summary. This chapter summarizes the research results and conclusions of the full text, and the future research direction of the broadband band spiral antenna will be summarized. At the same time, the design of this article needs to be improved.
Broadband band spiral antenna basic theory and design scheme
The spiral antenna is defined as an antenna formed by winding the wire into a spiral coil shape. Generally, it has a metal board or ground grid, and feeds on the coaxial axis. The internal conductor of the coaxial axis is connected to the spiral line. Polarization antenna; currently, there are usually some indicators for how to measure the performance of an antenna: direction diagram, directional factor, gain, input impedance, voltage resident ratio, antenna effective length and effective area, polarization and bandwidth, bandwidth, bandwidth Wait .
Broadband band antenna refers to the electrical characteristics such as the impedance and direction chart of the antenna (F_MAX/F_min = 2) or there are no significant changes in the range of several times.
Basic parameters of spiral antenna
The circuit parameters of the antenna and the far -field radiation parameters are functions that are transformed relative to frequency changes, which also allows the antenna to have a clear frequency characteristics. The bandwidth of the antenna indicates: the effective operating frequency range of the antenna, and the decisive effect on the antenna bandwidth is: the size of the antenna and the frequency characteristics of the antenna. Within the effective operating frequency range of the antenna, the resonance frequency is centered, and the departure of the resonance frequency has a allowable value. The frequency band within the allowable frequency range is called bandwidth. This article allows the deviation value to -10DB.
The definition of antenna bandwidth is generally divided into three types: relative bandwidth, absolute bandwidth, and frequency bandwidth. The bandwidth in this article uses multiplier bandwidth. The expression formula of the frequency bandwidth is shown in the formula (2.1):
Bw = f_max/f_min (2.1)
Among them, F_MAX represents the upper limit of the operating frequency, and F_MIN represents the lower limit of the operating frequency.
ΔF = F_H-F_L (2.2)
Among them, F_H is the high -end frequency of antenna, and F_L is the low -end frequency of antenna.
Bw_2 = (f_h-f_l)/f_0 (2.3)
Among them, F_0 is the center frequency, F_H is the high -end frequency of antenna, and F_L is the low -end frequency of antenna work.
The antenna input impedance is defined as the ratio of input voltage and input current of the transmission line port. Its expression is as shown in the formula (2.4):
Z_in (z) = (u (u (z))/(i (z)) (2.4)
U (Z) in the formula indicates the voltage of each point on the transmission line, and i (Z) represents the current on the transmission line.
When designing antenna, we must first meet the impedance of the antenna itself or the impedance of the same feeder port; and the type of antenna, the frequency of the antenna, the working environment, the structure size, and the processing materials of the processing materials are all right. The antenna input impedance has an important impact; the impact of changes in the frequency of the antenna on the frequency of frequency on the operating environment, structural size and other external factors are relatively sensitive. The degree of matching between antennas and feed wires will gradually deteriorate, resulting in increased reflection coefficients and voltage resident wave ratios on the feed wire, and the radiation efficiency of the antenna decreases.
The effective absorption or reflection of the energy when the radio wave is passed in an antenna depends on whether the impedance matches the corresponding operating frequency or bandwidth. When the impedance is not matched, we can use the antenna regulators, Baron, impedance converter, and matching networks containing capacitors and inductors to adjust; in general, when designing antennas, we will correspond to the simulation software and antenna corresponding to corresponding corresponding to the antenna. Knowledge optimizes the structure size of the antenna to achieve better impedance matching effects. Smith Chart is an effective way to analyze the problem of transmission line matching . You can also intuitively watch the impedance value of the antenna. In engineering applications, the input impedance of the general feed port input is 50Ω.
The direction diagram of the antenna refers to a curve chart that changes in the direction of the radiation field at a certain distance from the antenna. The plane and the plane) are represented by the direction diagram. The antenna direction chart is also called Radiation Pattern or Far-Field Pattern. In order Parameters such as the front and rear and direction coefficients, and the width of the waves is an important parameter of the antenna. Within a certain range, the verticality of the antenna can be used to improve the quality of the coverage. Figure 2.1, Figure 2.2 are the polar coordinate direction diagram of the antenna, and the native coordinates of the ingredients of the antenna:
Right -angle coordinates ingredient diagram
Define the ratio of reflex wave voltage (or current) at any point of the transmission line to Z
Γ_u = (u_- (z))/(u_+ (z)) (2.5)
Γ_i (z) = (i_- (z))/(i_+ (z)) (2.6)
The U_- (Z), I_- (Z) in the formula (2.5) and (2.6) represent the voltage and current of the microwave on the transmission line on the transmission line. The voltage and current.
We usually refer to the voltage reflex coefficient as the reflex coefficient and record it as γ (Z):
Γ (Z) = (Z_1-Z_0)/(Z_1+Z_0) E^(-jβz) = γ_1 E^(-j2βz) (2.7)
Γ_1 = (Z_1-Z_0)/(Z_1-Z_0) E^(-jβz) = | γ_1 | E^(Jϕ_1) (2.8)
Among them, γ_1 is called terminal reflex coefficient, Z_1 is terminal load impedance, Z_0 is the characteristic impedance of non -consuming transmission lines, and β is phase transition constant. So any reflex coefficient can be represented by the terminal reflection coefficient:
Γ (Z) = | γ_1 | E^(J (ϕ_1-2βz)) (2.9)
For uniformly non -consuming transmission cables, the size of the reflex coefficient at any position is equal. Only the phase of the transmission line varies according to the period. Repeatability.
The antenna efficiency is defined as the ratio of antenna radiation power to input power.
σ_A = p_σ/p_i = p_σ/(p_σ+p_1) (2.10)
Among them, P_σ is the radiation power, P_i is the input power, P_1 is ohm loss, and the antenna efficiency can also be represented by formulas (2.10)
σ_A = R_σ/(R_σ+R_1) (2.11)
In the formula, R_σ is the strength of the radiation resistance and the amount of radiation power of the antenna is used, and R_1 is the loss resistance; from the formula (2.11), it can be seen that the antenna efficiency should be improved and R_1 should be reduced.
The definition of antenna gain is that when the input probability is equal, the actual antenna and the ideal radiation unit at the same point of the space are recorded as G. The antenna gain can also be understood as: in the direction (θ, ψ) direction, the power density S (θ, ψ) of the antenna is the ratio of the ideal point source of the radiation power S_0 of the same power input . Because the antenna is a passive device, the signal cannot be enlarged. Its gain represents the degree of convergence of energy. The greater the gain, the narrower the beam, and otherwise it corresponds to the wide beam. Then its expression is visible (2.12):
G = d ((_a (2.12)
Among them, D represents the direction coefficient of antenna, η_a means antenna efficiency.
From the formula (2.12), the higher the antenna direction coefficient and antenna efficiency, the higher the gain coefficient, which means that the physical connection between them is quite close; in other words Compared with the direction of an antenna, the input power is enlarged by the maximum radiation direction.
The definition of the Bobby is: The ratio of voltage amplitude amplitude of the abdominal point on the transmission line to the voltage amplitude of the node node is expressed by ρ, and its expression is shown (2.13):
_ = | u | _max/| u | _min (2.13)
Because the upper voltage of the transmission line is formed by the incident wave voltage and the reflection wave voltage, the maximum voltage is in the same place in the same place as the incident wave and the reflection wave phase, and the minimum value is located in the opposite point of the incident wave and the reflection wave phase, so there is any
| U | _max = | u_+ |+ | u_- | (2.14)
| U | _min = | u_+ |- | u_- | (2.15)
Replace the formula (2.14) and (2.15) into the formula (2.13), and use the formula (2.5) and (2.6) to get it
= (1+ | γ_1 |)/(1-| γ_1 |) (2.16)
Formula (2.16) represents the relationship between the terminal reflection coefficient and the resident wave ratio; when | γ_1 | = 0, that is, when there is no reflex on the transmission line, the voltage resident wave ratio ρ = 1, and when | γ_1 | = 1, that is, the transmission line, that is, the transmission line When the upper reflection, the voltage stationbore ratio → ∞ → ∞, you can know that the value range of the voltage resident wave ratio ρ is 1 ≤ρ≤∞; it can be seen that the voltage resident wave ratio can be used to describe the working status of the transmission line as However, the voltage resident wave ratio is a real number that does not include phase information.
S parameters or scattering parameters describe the electrical behavior of the linear electrical network when the changing steady -state signal incentive is incentive. And the S parameter can also be converted to each other with voltage resident wave ratio. Below is the physical meaning of each parameter:
S_11 is the input reflection coefficient, and it is also the input return loss loss
S_12 is the reverse transmission coefficient, that is, isolation
S_21 is a positive transmission coefficient, that is, gain
S_22 is the output reflection coefficient, that is, back loss loss
The characteristics of the S parameter under the three special networks are as follows:
Easy Network: S_11 = S_12
Symmetric network: s_11 = s_22
Consumed network: 〖(s_11)〗^2+〖(s_12)〗^2 = 1
Settings of basic parameters
Working frequency: F = 2 ～ 16GHz
Circuit radius: r = 1mm
Spiral diameter: d = 8mm
Vertical distance between spiral coils: s = 7.5mm
Spiral height: H = 30mm
Direction of spiral circles: n = 4
Spiral week long: C = 25.12mm
Spiral angle: α = 〖16.66〗^0
Electromagnetic simulation software cst
CST is a comprehensive, accurate and integrated professional simulation software for three -dimensional electromagnetic, circuit, temperature, and structural stress design engineers. Electromagnetic algorithm and high -frequency algorithm. Its design environment is a channel for entering the studio set, supporting the synergy between sub -software, and the data is processed and exported after data. CST is designed by German CST Co., Ltd., and CST is currently the world’s largest pure electromagnetic field simulation software company. In China, CST China Lid is a branch of Germany CST in China.
CST EM Studio and Microwave Studio (CST Microwave Studio) are the two major studios used in this paper.
CST Electromagnetic Studio (CSTEMS) is a universal static electromagnetic, constant stable current, and low -frequency passive structure electromagnetic field simulation software. It has seven solutions (such as static electricity, static magnetic, low -frequency domains, etc.). The grid, limited integration and finite element can be applied within the range of electromagnetic torque calculation, electromagnetic field analysis, non -destructive detection, induction heating and other range.
CST Microwth Studio (CST MWS) is commonly used in mid-to-high-frequency passive devices simulation, suitable for all electromagnetic bands, design simulation and simulation analysis of HZ-THZ, THZ to light wave bands, filters, RCS, etc., calculate arbitrary materials and arbitrary structure Electromagnetic problems of devices; have nine types of time domain frequency domain full -wave algorithms and two high -frequency algorithms (such as: time domain limited integration, time domain transmission matrix, frequency domain limited integration, frequency domain finite element, bullet jump radio method, etc.),
The CST built -in FIT (limited accumulation method) algorithm is divided into two algorithms: time domain and frequency domain. FIT is the core algorithm of microwave studios (MWS) . The algorithm of FIT and FDTD is equivalent. FDTD (Limited Domains) is a differential form of the Maxwell Formula Group. It is generally used to calculate large -size objects. Its calculation speed is fast but not accurate. It has advantageous applications in terms of closing problems and biomagnetic effects. It is also relatively simple. The object is divided into a square grid, and the FDTD divides the space area where the object is located into a small -size unit unit, and assumes that the field in the volume unit is the constant. Because the algorithms of FIT and FDTD are equivalent under the right -angle coordinate system, the algorithm is as follows: first divide the calculated object space area into some columns of small blocks, and perform electric field strength E at the edge center of each cubic block. (X, y, z, t) sampling, perform magnetic field strength H (x, y, z, t) in the center of the cubic block of the cubic block (see Figure 2.3), then perform time sampling, the strength E and magnetic induction strength B For the time interval of equal time, but E and B sampling time points are staggered for half a time step (see Figure 2.4), and the remaining variable potential shift D and magnetic field strength H are expressed by this structure. Finally Together, the initial state, electric field incentive sources, and boundary conditions in the specified area space field are obtained. The algorithm alternates the effect of the electromagnetic field at each time.
Figure 2.3 Sampling diagram
Figure 2.4 Passing sampling time point
Maxwell equations are as follows:
⃗ ⃗ ∙ d ρ = ρ (2.17)
⃗ ⃗ ∙ B 0 = 0 (2.18)
⃗ ⃗*e-=-(∂B ⃗)/∂t (2.19)
⃗ ⃗*h j = J ⃗+(∂B ⃗)/∂T (2.20)
In the formula, ⃗ 散 散 indicates the scatterness, ∇ ⃗*indicates the rotation, ρ indicates the charge density (charge/volume), and J ⃗ indicates the current density (current/area).
Bandwidth matching technology
The quality of the antenna bandwidth directly affects the radiation distance of energy, so it is very important to match the antenna bandwidth, but it is not easy to match the bandwidth matching. Our common matching methods include single -double branches matching, T -type matching network, λ/4 impedance converter, broadband gradient transform, π -type network, dual -e -terms multi -section matching converter, etc. , specific methods such as Figure 2.5 shown:
Among the several matching methods mentioned above, the band of the dual -e -terms matching transformer response is the best in the meaning of the given number, and at the frequency of the design, the response will be as flat as possible, so the response will be as flat as possible, so This response is also called the flattest response. When we match the traditional spiral antennas, we usually leave 1/4 of the bottom of the spiral coil, and use the appropriate matching section or a certain degree of cone transition, such as adding a certain width impedance matching tablet on the conductor [14 14 [14 ].
Figure 2.5 several matching methods
Modeling of Broadband Band Spiral Apertper
Establish a model and simulation
Use CST simulation software to model and simulate the model. The model is shown in Figure 3.1:
Figure 3.1 Broadband band spiral antenna model diagram
Simulation results and performance analysis
The original picture of the antenna simulation, as shown in Figure 3.2:
Figure 3.2 antenna simulation original map
The antenna simulation voltage resident Bobbi changes the curve with the frequency, as shown in Figure 3.3:
From Figure 3.3, it can be seen that the voltage resident wave ratio vswr <1.16, the voltage resident wave ratio of an antenna is still ideal; The connection is ideal, and in the current international standards, in the case of the default voltage resident wave ratio than 2, the antenna has a good matching situation, so the antenna designed in this article also has good matching.
The S parameter after simulating the antenna is shown in Figure 3.4:
Figure 3.4 Antenna Simulation S parameter
From Figure 3.4: The input rebate loss S11 in the set band of the antenna is relatively small, the overall is less than -20dB, and the resonance frequency point is close to -90dB when the resonance frequency point is 6.45GHz. GHz, the total bandwidth of the antenna is 0.44GHz.
When the frequency is f = 2GHz, F = 9GHz, F = 16GHz, the antenna simulation gain chart is shown in Figure 3.5:
Figure 3.5 antenna simulation gain chart
It can be obtained from Figure 3.5: the maximum gain of the antenna is 40.1DBI. As the frequency becomes larger, the gain of the antenna gradually becomes larger, and the increase in gain is relatively large, and the increase is relatively small.
When the frequency is f = 2GHz, F = 9GHz, F = 16GHz, the E -plane direction diagram of the antenna and the H plane direction chart are shown in Figure 3.6:
At F = 2GHz, the direction coefficient of the antenna is 4.256DBI, the radiation efficiency is 35.80dB, and the total radiation efficiency is -44.20db; f = 9GHz, the direction coefficient of the antenna is 7.156dbi, the radiation efficiency is 0.3944DB, and the total radiation efficiency is -26.23db; f = 16GHz, the direction coefficient of the antenna is 9.240dbi, the radiation efficiency is 0.1723DB, and the total radiation efficiency is -10.75DB. The radiation efficiency in this simulation refers to the loss of copper materials. The total radiation efficiency is the total efficiency of the echo loss of port matching in addition to the radiation efficiency.
From the H surface diagram of the antenna: when F = 2GHz, F = 9GHz, F = 16GHz, the width of its 3DB wave petals is 〖99.3〗^0, 〖127.8〗^0, 〖24.9〗^0 , The width of the main petals is 〖97.0〗^0, 〖65.0〗^0, 〖91.0〗^0; the designed antenna in the 2GHz ~ 9GHz band, the 3DB wave width of the antenna gradually becomes larger, and the working benefits of the antenna gradually gradually become larger. The difference is worse. In the 9 to 16GHz band, the width of the 3DB wave petals of the antenna gradually becomes smaller, and the working efficiency of the antenna gradually becomes better.
From the e -surface map of the antenna: the width of the 3DB of the petals is 〖91.0〗^0, 〖103.7〗^0, 〖100.5〗^0, the width of the main petals is 〖102.0〗^0, 〖179.0〗^0 〖356.0〗^0; To optimize the width of the 3DB of the antenna, you can use the height method of increasing antenna. If the height of the antenna is adopted, it has a negative impact on the antenna impedance matching and the direction of the antenna. In height, the radiation characteristics of the antenna will deteriorate. Therefore, you cannot blindly increase the height of the antenna, and to optimize the parameters of the antenna.
Analysis of the antenna
Analysis of antenna coil n
When the number of circles of antennas is taken n = 3, n = 4, n = 5, n = 6, respectively, simulation of the antenna: N = 3, the broadband range of the antenna is 6.42 to 6.66GHz, the total bandwidth It is 0.42GHz; n = 4, the antenna bandwidth range is 6.18 ~ 6.62GHz, and the total bandwidth is 0.44GHz; n = 5, the antenna bandwidth is 6.29 to 6.50GHz, the total bandwidth is 0.21GHz; The antenna bandwidth range is 6.31 ~ 6.60GHz, and the total bandwidth is 0.29GHz. Table 3.1 The relationship between the antenna coil and the antenna bandwidth:
Table 3.1 The relationship between the antenna coil and bandwidth
Antenna coil n simulation bandwidth total bandwidth
36.24 ~ 6.66GHz0.42GHz
46.18 ~ 6.62GHz0.44GHz
56.29 ~ 6.50GHz0.21GHz
66.31 ~ 6.60GHz0.29GHz
After analysis of coil N: When the number of coils is within 3 to 6 times, at N = 4, the antenna bandwidth reaches the maximum value; when the antenna coil is increased to more than 4 laps, the width of the antenna is significantly large Reduce.
The changes in the number of antenna coils and its gain are shown in Figure 3.7:
Figure 3.7 Chart of a change in the antenna coil and gain
From Figure 3.7, it can be seen that when the number of coils is 3 to 6 times, the number of coils at N = 5 is the largest.
Analysis of the outer radius R of an antenna reflector
When the outer pulse of the antenna is 20mm, 30mm, and 40mm, the antenna is simulated to simulate the antenna: R = 20mm, the bandwidth range of the antenna is 6.19 ~ 6.72GHz, and the total bandwidth is 0.53GHz; R = 30mm, the bandwidth range of the antenna, the bandwidth range of the antenna, In 6.18 ~ 6.62GHz, the total bandwidth is 0.44GHz; R = 40mm, the bandwidth range of the antenna is 2.05 ～ 2.3GHz and 2.70 ~ 3.14GHz, the total bandwidth is 0.69GHz; Table 3.2 represents the relationship between the outer radius of the antenna coil and bandwidth:
Table 3.2 The relationship between the outer radius and bandwidth of an antenna reflective board
The outer radius of the antenna reflective plate R simulation bandwidth total bandwidth
20mm6.19 ~ 6.72GHz0.53GHz
30mm6.18 ~ 6.62GHz0.44GHz
40mm6.17 ~ 6.66GHz0.49GHz
After analysis of the half -R outside the antenna: When the outer radius of the antenna reflective plate is R = 20mm, the bandwidth of the antenna is the ideal.
Antenna microwave radiation analysis
The magnetic field radiation diagram under the three frequencies of 2GHz, 9GHz, and 16GHz is as shown in Figure 3.8 and electric field radiation chart as shown in Figure 3.9:
Figure 3.8 antenna magnetic field radiation chart
Figure 3.9 Floor Electric Field Radiation Chart
From Figure 3.8 and Figure: In the 2 to 16GHz band, with the increase in frequency, the distribution density of the antenna’s electromagnetic field in free space gradually increases, and the strength and magnetic field strength of the antenna are gradually increasing, which leads to an antenna The direction coefficients have been gradually increasing, and the working performance of the antenna is also good; the maximum values of the electric field in 2GHz, 9GHz, and 16GHz are 3697.6V/m, 9848.35V/m, 25093.8V/m. The magnetic field is 2GHz, 9GHz, 9GHz, 9GHz, 9GHz The maximum value of 16GHz is 38.657a/m, 20.1123A/m, 21.1778A/m.
Local optimization of the model
Using the Nelder Mead Simplex Algorithm (Nildmi Simple Algorithm) algorithm in the local optimizer optimizes the model. This algorithm is a local optimization algorithm. The range is 28-32mm, and the optimization results are shown in Figure 3.9:
Figure 3.9 Optimized results map
From Figure 3.9, it can be seen that the antenna spiral height H is optimized within 28 to 32mm. When the antenna spiral height is 30.819mm, the value of the S11 is the smallest. Change,
Broadband band spiral antennas and micro -band spiral antenna comparison analysis
Design and simulation of micro -band spiral antenna
Plane -based angle spiral antenna  is a micro -band spiral antenna that is completely determined by the angle. Its curve equation is
〖R = r〗 _0 e^(A (φ-φ_0)) (4.1)
Among them, R_0 is the veil of the spiral starting angle φ_0, A is the spiral growth rate of the spiral coil, and φ_0 is the spiral starting angle of the spiral coil.
After a large number of previous trials, the radius of the antenna is usually selected by the minimum operating frequency of 1/4, and the minimum radius is selected as the maximum operating frequency corresponding to 1/4 .
The parameters of the equal angle plane spiral antenna designed in this article are: the operating frequency is 2 to 16GHz, which is
λ = c/f (4.2)
(Among them, λ is the wavelength, C is the speed of light in real vacuum 3.0*108m/s, F represents frequency) The wavelength of the spiral line at 2GHz and 16GHz is 150mm and 18.75mm, respectively. The spiral antennas designed in this article are self -complementary types, R = 2mm, α = 20^0, and the substrate uses Rogers RT5880 (Loss Free), the thickness is 1mm, the relative dielectric constant ε = 2.2, and the start -end setting of the antenna. The antenna model is shown in Figure 4.1:
Figure 4.1 Corner spiral antenna model map
The simulation of the plane and other corner spiral antennas is as shown in Figure 4.2:
Figure 4.2 Simulation original map
The S parameters of the corner spiral antenna of the plane are shown in Figure 4.3:
Figure 4.3 Corner spiral antenna S parameter chart
From Figure 5.3: The input return loss of the antenna S11 is larger, the minimum value is only close to -16DB, the large is close to 1DB, the resonance frequency of the antenna is 4.35GHz, and its bandwidth range is 4.21 to 4.49GHz. The total bandwidth is 0.28GHz Essence
The antenna gain chart of the three frequency points in the frequency band of the plane is the antenna gain chart of the three frequency points in the frequency band. As shown in Figure 4.4:
Figure 4.4 Grane spiral antenna gain map
It can be seen from Figure 5.4 that the gain within the frequency of the antenna is gradually increasing, reaching the maximum value at F = 16GHz; the maximum gain at 2GHz, 9GHz, 16GHz frequency points is -3.99dbi, 3.93DBI, 5.6 DBI, the gain is not ideal in the 2 to 6GHz band; for the gain of the increase in the plane spiral antenna, the most common method is to add a reflective board at a position of 1/4 wavelength of the spiral antenna, the literature [17, 18, 19] Both are classic examples of using reflective boards to increase antenna gain.
The direction diagram of the E plane of the antenna and the H plane, as shown in Figure 4.5:
Figure 4.5 The direction chart of E plane and H plane
At F = 2GHz, the direction coefficient of the antenna -3.401dbi, radiation efficiency -0.592db, total radiation efficiency -10.34db; when F = 9GHz, the direction coefficient of the antenna is 3.920dBi, the radiation efficiency is 0.008DB, and the total radiation efficiency -1.858db ; F = 16GHz, the direction coefficient of the antenna is 5.517dbi, the radiation efficiency is 0.085DB, and the total radiation efficiency is -3.078DB.
Analysis from the direction of the antenna H face: The width of 3DB wave petals at the three frequencies of the antenna at 2GHz, 9GHz, and 16GHz is 〖95.8〗^0, 〖94.8〗 〖180.0〗^0, 〖180.0〗^0, 〖180.0〗^0; the width of the antenna’s 3DB petals in the range range of the setting band gradually decreases, the working performance of the antenna in the full frequency band is better.
Analysis from the direction of the antenna e -faces: 3DB wave petals widths at the three frequencies of the antenna at 2GHz, 9GHz, and 16GHz are 0, 〖86.4〗^0, 〖75.8〗^0, and the width of the main petals is 〖180.0〗^^^^^ 0, 〖180.0〗^0, 〖180.0〗^0; the antenna 3DB of petals in the 2-9GHz band gradually increases, the antenna work performance is poor, and the 3DB wave petals in the 9 to 16GHz band gradually decrease, then the antenna will then the antenna The work performance gradually becomes better.
Comparison analysis of two antennas
Bandwidth contrast analysis
Table 4.1 summarizes the broadband performance of the two antennas. From Table 4.1, it can be obtained: the simulation bandwidth of the broadband band spiral antenna is 6.18-6.62GHz; the simulation bandwidth of the corner spiral antenna of the plane is 4.21 ～ 4.49GHz. The total bandwidth of the broadband band spiral antenna is 0.44GHz, while the total bandwidth of the angle spiral antenna of the plane is 0.28GHz. Compared with the width band spiral antenna, the bandwidth is better than the corner spiral antenna.
Table 4.1 The bandwidth of the two antennas
Antenna simulation bandwidth total bandwidth
Broadband band spiral antenna 6.18 ~ 6.62GHz0.44GHz
Corner spiral spiral antenna 4.21 ~ 4.49GHz0.28GHz
Radiation contrast analysis
The radiation parameters of the two antennas are shown in Table 4.2:
Table 4.2 Radiation parameter comparison
Frequency broadband band spiral antenna plane and other corner spiral antennas
3DB wave petal width direction coefficient 3DB wave petal main petal width direction coefficient coefficient
2 〖99.3〗^0 〖97.0〗^04.256dbi 〖95.8〗^0 〖180.0〗^0-3.401dbi
9 〖127.8〗^0 〖65.0〗^07.156dbi 〖94.8〗^0 〖180.0〗^03.920dbi
16 〖24.9〗^0 〖91.0〗^09.240dbi 〖70.8〗^0 〖180.0〗^05.517dbi
The maximum total radiation power of the broadband band spiral antenna is 0.043, and the maximum total radiation power of the corner spiral antennas of the plane is 0.33,
In contrast, it can be seen that the overall radiation characteristics are better than the corner spiral antennas of the plane.
Gain comparison analysis
The gain comparison of the two antennas is shown in Figure 4.6:
Figure 4.6 gain comparison chart
From Figure 4.6, you can obtain: the gain of the broadband band spiral antenna is 9.41 ~ 40.10dbi; the gain of the corner spiral antenna of the plane is -3.99 ～ 5.60dbi. The gain of the second antenna has been increasing: In contrast, it can be seen that the gain of the broadband band spiral antenna is far better than the corner spiral antennas.
After the above analysis, the broadband spiral antenna parameters in broadband, gain, impedance matching, and microwave radiation performance are better than the spiral antenna of the micro band.
This article introduces the theoretical knowledge and design requirements of the spiral antenna, and then uses CST to build an imitation calculation of 2 to 16GHz single -arm spiral antennas and graphic spiral antennas.
Began to understand the background of the development status of the broadband antenna at home and abroad, and the second chapter of the display of the basic theoretical knowledge of the spiral antenna and the determination of design requirements. In the end, Chapter 4 performs a design simulation calculation of the micro -band spiral antenna and compares and analyzes the results of the broadband band spiral antenna. This article mainly shows the superiority of the bandwidth of the broadband band, and the performance of the comparison of the micro -band antenna. It compares the superiority of the broadband band spiral antenna in some aspects.
Use the simulation software CST to optimize the parameters and finally determine the parameters of the antenna. After the simulation, the parameters of the antenna, voltage resident ratio, gain and other parameters are basically ideal. The width of the 3DB wave petals of the antenna is not ideal at 9GHz. Compared with the micro -band spiral antenna, the broadband band spiral antenna has a good bandwidth bandwidth sex.
The development of broadband antennas has been developed for more than ten years, and there are countless research on various broadband antennas, and most of them have succeeded. The research on this article is only a very small part of it. The broadband band antenna designed by the author also has improved places, such as improving the height of the spiral antenna, making it smaller, without having to take up too much space, and its ones. How to widen the width further and so on, these are studied in future topics.
Liu Qingxiang, Li Xiangqiang, Yuan Chengwei, Zhao Liu, Wang Xin, Li Jun. High-power double-layer radial line spiral array antenna theoretical analysis and numerical simulation [J]. Electronic Journal, 2005, (12): 2231-2234.
Research on the best design method of Yang Fei.
Research on Cui Chao. Smallized spiral antenna system [D]. Shanghai: East China Normal University, 2011.
Zhu Lidong, Wu Yanyong. Satellite Communication Introduction [M]. The fourth edition. Mens in Wanshou Road, Haidian District, Beijing: Electronic Industry Press, August 2002: 4-11.
Chen Xin. A new type of ultra -broadband small antenna [D]. Harbin: Harbin University of Technology, 2007.
Shu Na. Gas insulation combination based on chaos theory Electric discharge narrow band noise and identification research [D]. Chongqing: Chongqing University, 2013.
Aijun Gu,Shiwen Yang,Zaiping Nie. Analysis and Design of Miniaturized Ultra-Wideband Conical Log Spiral Antennas[C]. IEEE:Cross Strait Quad-Regional Radio Sciennce and Wireless Technology Conference.2013:191-194.
Zhang Ge. Research and design of broadband antenna [D]. Xi’an: Xi’an University of Electronic Science and Technology, 2014.
Lin Changlu, Nie Zaiping. Announcement Handbook [M]. The first edition. Performance of Wanshou Road, Haidian District, Beijing: Electronic Industry Press, June 2002: 5-16.
Tong Renbin. S -band continuous F -type power amplifier study [D]. Chengdu: University of Electronic Science and Technology, 2014.
Liu Xueguan, Guo Huiping. Microwave technology and antenna [M]. Fourth edition. Xi’an Tai Bainan Road No. 2: Xi’an University of Electronic Science and Technology Press, September 2018: 11.
Yu Xianwei. Research and design for dual -frequency micro -band antenna applicable to wireless local area network [D]. Nanjing: Nanjing University of Aeronautics and Astronautics, 2011.
Weiland T, Timm M, Munteanu I. A Practical Guide to 3-D Simulation [J]. IEEE Microwave Magazine, 2008, (9): 6. 6.
Roning. The research and design of the broadband circle polarized spiral antenna [D]. Shenzhen: Shenzhen University, 2014.
Study on Ma Fubao. The study of the round -polar antenna of the round band of the UHF band [D]. Xi’an: Xi’an University of Electronic Science and Technology, 2017.
Sharaiha,A. Terre,C,Analysis of Quadrifilar Resonant Printed Helical Antenna for Mobile communications[J]. Microwaves,Antennas and Propagation,IEEE Proceedings-H Vol, 140,1993:269-273.
Xia Chenggang. Plane and other corner spiral antennas and Barren’s design [D]. Guangdong: South China University of Technology, 2010.
Ahn J, CHA S H, CHA S G, Yoon Y J. Compact Spiral Element for Wideband Beam-Steering Arrays [J]. IEEE ANTENNAS & Wireless Propagation Letters, 2017, 16: 1994-1997.
Garía-Estellés A, Sánchez-Martínez J J, Gago-Lancho A C,Vázquez-Vázquez F. Compact cavity-backed spiral antennas with enhanced axial radio and gain at low frequencies[C]. IEEE:European Microwave Conference(EuMC),2018: 392-395.