Design, simulation and construction of a new microstrip antenna with the ability to control multiple frequency bands

Number of pages: 113 File Format: word File Code: 31379
Year: Not Specified University Degree: Master's degree Category: Electronic Engineering
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  • Summary of Design, simulation and construction of a new microstrip antenna with the ability to control multiple frequency bands

    Dissertation for Master's Degree in Telecommunication Electricity (Field)

    In this thesis, a patch microstrip antenna with very effective changes in the ground plane and its radiation part is studied to increase efficiency, create various modes of frequency response and the possibility of controlling these modes. The changes applied to this antenna have created a new structure of microstrip antennas, which has a format similar to a microstrip patch antenna and a quasi-monopole function. The design of the structure presented in the first part is started from a microstrip patch antenna. The dimensions of the antenna are equal to 34 x 20 square mm. To achieve the desired results, the ground plane and radiation patch have been significantly modified. These changes in the first stage include applying a pair of U-shaped slots on the ground plane. For the first time, a pair of opposite U-shaped slits (their rules facing each other) are located in the plane of the Earth. These gaps play the role of an effective resonator whose resonance frequency is determined according to their position and dimensions. Then a slot with a composite shape is created on the radiation patch. Parametric simulation has been investigated on the influencing parameters to optimize the performance. Considering these corrections, two broad bands, 1.38-3.98 GHz and 5.15-15.2 GHz are covered. In the second part of the antenna design, a very small slot is added in a certain part of the ground plane. This slot plays the role of a switch in the antenna, so different frequency responses such as single-band or multi-band modes as well as narrow band or wide band can be achieved in the entire frequency band of 1.5-6 GHz. In this section, the location of the slot has been investigated and optimized for better performance.

    Microstrip antenna, its definition and structure

    1-1 Definition of microstrip antenna

    The concept of microstrip radiators was first proposed by Deschamps in late 1953 and the first practical antenna was built in 1970. Since then, extensive research has been done on various microstrip antennas. A microstrip antenna in its simplest configuration, as shown in Figure 1-1, consists of an insulator with a dielectric constant of less than 10 ( ) with a ground plane on one side and a radiation plane on the other side. The radiation conductor plate is generally made of gold and copper. This conductor can have different shapes, but usually shapes are used that are expected to perform well and can be analyzed easily. Different types of insulators have different dielectric constant and loss tangent. Ideally, in the antenna topic, the dielectric constant of the insulator should be less than 2.5 to increase the scattering and radiating fields [1].

    Figure 1-1: Simple microstrip antenna configuration[1[.

    1-2 Advantages and disadvantages of microstrip antennas

    Microstrip antennas have several advantages over conventional microwave antennas, which make them used in the range The frequency range has been widened from 100 MHz to 100 GHz, some of these advantages are:

    1

    1) having a low weight and volume and a plate structure with a low thickness

    2) the possibility of manufacturing very cheaply for mass production

    3) the simplicity of integrated manufacturing with MICs on a substrate

    4) the possibility of having linear or circular polarization with feeding methods Easy

    5) The possibility of designing for two-frequency and two-polarization mode

    6) Feeding lines and matching networks are built simultaneously with the antenna structure.

    Microstrip antennas, despite having these advantages, have the following disadvantages:

    1) Narrow bandwidth and issues related to manufacturing error

    2) Lower gain

    3) High ohmic losses in the array feeding structure

    4) Half-plane radiation

    5) Having a complex feeding structure for arrays

    6) Having poor polarization purity[1]

    7) Sub-radiation from feeding and connection points

    8) Surface wave excitation

    9) Poor power management capabilities

    Narrow bandwidth microstrip antennas on the order of 1 They have up to 5% in normal mode, which is the main limiting criterion for the applications of these antennas. Most efforts of researchers in this category have been spent on increasing the bandwidth of these antennas, and bandwidths up to 70% have been obtained [2] and [3].

    1-3 types of microstrip antennas

    2

    Microstrip antennas are described by a large number of physical parameters compared to conventional microwave antennas. These antennas have different types with their own characteristics and are used for various applications according to the desired specifications. All microstrip antennas are divided into four main categories:

    microstrip patch antennas

    microstrip dipole antennas

    microstrip slot antennas

    wave microstrip antennas

    1-3-1 patch antennas[2] microstrip

    These antennas include a flat patch or non-planar that is on one side of the dielectric and the ground plane on the other side of the dielectric. The thickness of the patch is generally considered. There are many sub-layers that are used to design microstrip antennas and their dielectric constants are usually in the range of 2.2 to 12. The height of the substrate is in these antennas. Low dielectric constants have high efficiency and more bandwidth, which of course is associated with the greater height of the substrate. Thin substrates with higher dielectric constants are desirable for microwave circuits because they require confined fields to minimize unwanted radiation, but will have lower bandwidth and efficiency. The patch has different shapes. The most important ones that have practical applications and are mostly used in the design of antennas are shown in Figure 1-2 [1]. Patch antennas have a gain of 5 to 6 dB and the range of dB3 beam width is from 70 to 90 degrees [1].

    1-3-2 bipolar antennas [3] Microstrip

    These type of antennas have a different length to width ratio compared to the patch. The width of dipole antennas is usually smaller than 0.05. The radiation patterns of patch and dipole antennas are the same due to the similar longitudinal current distribution on them, but their radiation resistance, bandwidth and cross polarization are very different [4] and [5]. Microstrip dipole antennas are considered because they create linear polarization and occupy little space, so they are suitable for arrays. These antennas are widely used in very high frequencies, and for this purpose, their thick sublayer (representing the capacitor with plates far apart, reducing the stored energy and reducing the quality factor) is chosen in order to obtain the appropriate bandwidth. The feeding network for these antennas is very important and must be considered in the analysis phase. In Figure 1-3, you can see an example of microstrip dipole antennas fed by the proximity method [1].

    Figure 1-3: Dipole antenna with proximity feeding [1].     

    1-3-3 Microstrip slot antennas[4]

    4

    ?0 In this type of antenna, a slot is placed in the ground plane of a grounded substrate. Figure 1-4 shows some forms of this type of antenna. This type of antenna is fed using microstrip lines or coplanar waveguide [5]. These antennas are usually two-way emitters because they radiate on both sides of the slot. Unidirectional radiation is obtained when a reflective plate is placed on one side of the slot [1]. Slot antennas have advantages over patch antennas. For example, they create more bandwidth, and basically, with slot antennas, you can make the antenna as compact as possible. These antennas are explained in detail in the third chapter. Figure 1-4: Some examples of microstrip slot antenna structures [1]. They are wide enough to establish a TE wave. These antennas are adapted by a resistive load to prevent the generation of standing waves. If the antenna system is designed in such a way that the load connected to the end of the antenna has a high impedance matching with the whole system, then the wave created by the source at the end of the antenna is not returned, and this particular type of antenna is known as traveling wave antenna.

  • Contents & References of Design, simulation and construction of a new microstrip antenna with the ability to control multiple frequency bands

    List:

    Chapter 1 Microstrip antennas, their definition and structure

    Definition of microstrip antenna 1.

    Advantages and disadvantages of microstrip antennas. 1

    Types of microstrip antennas. 2

    Microstrip patch antennas. 3

    Microstrip dipole antennas. 4

    Microstrip slot antennas. 4

    Waving microstrip antennas. 5

    Applications of microstrip antennas. 7

    Types of feeding methods for microstrip antennas. 8

    Microstrip line. 8

    Coaxial probe. 9

    Proximity coupling 10. Aperture coupling. 12. Waveguide feeding. 13. Microstrip antenna analysis methods. 13. Transmission line model. 14. Lip effects. 14. Effect of effective length on resonance frequency. 16. Microstrip antenna design. 17

    The housing model. 18

    B

    Arranging the fields (modes)-  19

    Density of equivalent currents. 23 Important parameters in checking the performance of microstrip antennas. 27

    Frequency bandwidth (impedance). 27

    Radiation pattern. 28

    Directionality and gain. 28

    Input impedance in microstrip antenna. 29

    Increase Bandwidth of microstrip antennas.30

    Chapter Two Introduction of microstrip and printed monopole slot antennas

    Slot antenna..33

    Introduction of slot antenna. 33

    Feeding methods of microstrip slot antennas. 34

    Design of slot antenna fed with microstrip line. 36

    Broadbanding methods of microstrip slot antennas. 36

    Introduction of types of microstrip slot antennas. 37

    Square ring slot antenna. 37

    Circular ring slot antenna. 38

    Narrowing slot antenna. 39

    Monopole antenna. 47

    Conclusion .. 50

    T

    Chapter 3 Types of combined monopole-slot antennas (Monopole - Slot Antenna)

    Introduction .. 52

    First type antenna .. 53

    First structure: slot 53

    Second structure: L-shaped slot with three different modes for feeding. 54

    Third structure: T-shaped slot with horizontal feed line. 57

    Fourth structure: two L-slots with two vertical-diagonal combined feeding. 58

    Second type antenna. ..67

    The fourth chapter of quasi-monopolar microstrip antenna with two broad bands and frequency response control capability

    Abstract..68

    Introduction ..69

    Antenna design and parametric study. 70

    4-3-1 Design and practical results of quasi-monopolar microstrip antenna with two broad bands. 70

    4-3-2 Design and practical results of pseudo-monopolar microstrip antenna with two wide bands and frequency response control capability

    ..82

    Chapter Five General conclusion and suggestions for future studies

    4-4 General conclusion.85

    4-5    Suggestions for future studies.86

    References  ..87

    Th

     

     

    Forms list

    Chapter 1 Microstrip antennas, their definition and structure

    Figure 1-1 Simple microstrip antenna configuration. 1

    Figure 1-2 Different forms for microstrip patch. 3

    Figure 1-3 Dipole antenna with proximity feeding. 4

    Figure 4-1 Some examples of microstrip slot antenna structures. 5

    Figure 5-1 Different types of wave microstrip antennas. 6

    Figure 1-6 Feeding by the method of microstrip line in the form of an edge and its equivalent circuit. 9

    Figure 1-7 Feeding by the method of microstrip line through a slot and its equivalent circuit. 9

    Figure 1-8 Antenna with feeding by the coaxial cable method: (a) Antenna schematic. (b) Equivalent feeding circuit 10. Figure 9-1 Antenna with electromagnetic coupling feeding: (a) antenna scheme. (b) Feeding equivalent circuit. 11

    Figure 1-10 Antenna with aperture feeding: (a) Antenna scheme. (b) Feeding equivalent circuit. 12

    Figure 11-1 Antenna with waveguide feeding. 13

    Figure 12-1 Microstrip line and its corresponding electric field lines. 15

    Figure 1-13 Dielectric constant affecting15

    Figure 13-1 Effective dielectric constant based on frequency for common substrates. 16

    Figure 14-1 Physical and effective length of rectangular microstrip antenna. 16

    Figure 15-1 Charge distribution and formation of current density on microstrip patch. 18

    Figure 16-1 Microstrip patch antenna geometry 20

    Figure 1-17 Geometry of rectangular microstrip patch antenna. 23

    Figure 18-1 Equivalent current density on four sides of patch antenna with and without flat ground. 24

    Figure 1-19 Radiation slots in rectangular microstrip antenna and equivalent magnetic current densities. 26

    Figure 20-1 The common pattern in plates E and H related to each of the radiating grooves and the sum of both of them. 26

    C

    Figure 21-1 Current density on the non-radiating grooves in the rectangular microstrip antenna. 27

    Figure 22-1 The resistance and reactance change curve of a microstrip antenna according to Frequency. 29

    Figure 23-1 The effect of change in thickness and dielectric constant on VSWR<2 impedance bandwidth and radiation efficiency. 32

    Chapter Two Introduction of printed microstrip and monopolar slot antennas

    Figure 2-1 Field distribution on the slot. 34

    Figure 2-2 Slot antenna with microstrip line feeding: (a) Antenna scheme and short circuit end method. (b) Open circuit end method. 35

    Figure 3-2 Methods of reducing the radiation resistance seen by microstrip line feeding. 35

    Figure 4-2 Important parameters in slot antenna design. 36

    Figure 2-5 Square ring slot antenna. 37

    Figure 2-6 Square ring slot antenna with return loss curve diagram resulting from the optimal antenna parameters. 38

    Figure 2-7 Fractal square ring slot antenna in the form of a peninsula and its return loss curve. 38

    Figure 2-8 Ring slot antenna. .39

    Figure 2-9 Tapered slot antenna. 40. Figure 2-10 Types of tapering antennas. (a) Vivaldi (b) LTSA (c) CWSA 44. Figure 2-13 S11 diagram for different values ??of L1 (= 1 W1 mm). 45

    Figure 2-14 S11 diagram for different values ??of L2 (= 6 W2 mm). 46

    Figure 2-15 S11 diagram for different values ??of W2 (= 1 L2 mm).

    Figure 2-16 Printed monopole antenna with three horns feeding. 49

    H

    Figure 2-17 The results of measurement and computer analysis of the VSWR parameter for the monopole antenna presented in [27]. 49

    Figure 2-18 of radiation patterns measured in H-plane for the monopole antenna presented in [27], for the frequencies: a) 3 GHz, b) 7 GHz, c) 11 GHz and d) 15 GHz. 50

    Chapter 3 Types of monopole-slot hybrid antennas (Monopole - Slot) Antenna) Figure 3-1 Single-pole-slit antenna with a rectangular slot on the FR4 board: (a) antenna structure and (b) its return loss diagram. 53. Figure 3-2 Return loss diagram of a single-pole slot antenna with a rectangular slot on a substrate with a dielectric constant equal to 2.5 and very low loss. 54 Figure 3-3 Structure of a slotted antenna with a slot L shape and three different modes for microstrip feed line. 55

    Figure 3-4 Return loss parameter for three different modes Figure 3-3.56

    Figure 3-5 Return loss parameter for Figure 3-3-a with substrates with dielectric constant 2.5 and negligible losses. 56

    Figure 3-6 Slotted antenna with T-shaped slot and horizontal feed line: a) Antenna structure. b) return loss diagram for FR4 substrate and c) return loss diagram for substrate with dielectric constant 2.5 and low loss. 57

    Figure 7-3 Slotted antenna with two L-shaped slots and a pair of vertical-diagonal combined feeding line. 58

    Figure 3-8 Combined monopole-slotted antenna Reference [30]: a) Antenna structure (top view). b) The structure of the antenna (view from the side of the antenna) and c) Dimensions and placement of two rectangular and L-shaped slots on the ground plane of the antenna. 59. Figure 9-3 Return loss diagram of the antenna in Figure 8-3 with dimensions specified in that figure for measurement and simulation situations. 60

    Figure 10-3 The return loss diagram of the antenna of Figure 8-3 and comparing it with the cases where only each of the slots exists at the same time. 61

    Figure 11-3 The structure of the proposed antenna of the third type.

Design, simulation and construction of a new microstrip antenna with the ability to control multiple frequency bands