Assignment 1 - Antenna Analysis

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Name Shengyu Xia: Number: MIT170811

  1. Introduction

In the field of antenna design, the term radiation pattern (or antenna pattern or remote field pattern) is a directed (Angle) dependence of the radio waves from the antennas or other sources. Especially in optical fibre, laser, and integrated optics field, the term radiation pattern can also be used as a synonym for near-field pattern or Fresnel. This involves the electromagnetic field in the source of the near field or the location of the area of the Fresnel dependencies. The near-field pattern is usually placed in front of the ligh

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e Shengyu Xia: Number: MIT170811

  1. Introduction

In the field of antenna design, the term radiation pattern (or antenna pattern or remote field pattern) is a directed (Angle) dependence of the radio waves from the antennas or other sources. Especially in optical fibre, laser, and integrated optics field, the term radiation pattern can also be used as a synonym for near-field pattern or Fresnel. This involves the electromagnetic field in the source of the near field or the location of the area of the Fresnel dependencies. The near-field pattern is usually placed in front of the light plane or on the surface of the cylindrical or spherical that surrounded it defined on. In this report, we have used the numerical analysis methods to critically review and analyze mobile and satellite communication systems. At the same time, we also identify engineering techniques to solve problems related to antenna and GSM laboratories.

  1. Method

The angular variation of the radiation produced by an antenna is often mapped as a graphical representation called a “radiation pattern”. In fact, the radiation pattern is perhaps the most important characteristics of an antenna. The radiation pattern can be obtained by plotting the powers at different angles. The main formulas required for constructing radiation pattern is below:

(1)

 (2)

Now we give the detailed steps to show how to construct the radiation pattern by numerical method. We have 4 data files in .csv format that represent results for measured radiated power of an antenna versus azimuthal angle φ and elevation angle θ. File Phi.csv contains a column of azimuthal angles φ from 0-360 degrees. File P_phi.csv contains a column of measured radiated power in Watts in the direction of angle φ with matching index, e.g. fifth row in P_phi.csv (P(5) value) corresponds to fifth row in Phi.csv (φ(5) value). File Theta.csv contains a column of elevation angles θ from 0-360 degrees. File P_theta.csv contains a column of measured radiated powers corresponding to θ angles.

Step1: import files

First open the Matlab software and build a blank script, the code is attached in below. These matlab codes can import the values from the files into the variables.

clear all

Phi= csvread(‘Phi.csv’);

P_phi= csvread(‘P_phi.csv’);

Theta= csvread(‘Theta.csv’);

P_theta= csvread(‘P_theta.csv’);

Step 2: Preliminary parameter calculations

The first is to find the angle in direction of which radiation is maximum, we can use the max() function to find. Then convert the angles into radians and normalize the power by dividing the maximum power. The codes are below.

phi_rad=(Phi/180)*pi;

Maxnum=max(P_phi);

P_phi_n=P_phi/Maxnum;

Step 3: Plot antenna radiation pattern

We use “plot_dB.m” Matlab program to plot radiation pattern for powers in dB versus azimuthal angle φ. Since we have finished the preparation work, so the code is easy to work out as

polar_dB(phi_rad,P_phi_n,20,3);

The output picture can be easily exported by clicking save as button.

Step 4: Parameter calculations

First we write code to calculate P ratio in dB and calculate the beamwidth of the antenna in horizontal plane. The beamwidth is the range of angles within which amplitude falls to 0.707 of maximum level or power falls to 0.5 (or -3dB) of maximum level.

db_P=10*log(P_phi_n); % converting in to dB scale

[Maxdb,index]=max(db_P); % find the max dB

[Ldb,lindex]=find(abs(db_P+3) < 0.1); %find the 3dB below the max dB, then the beam width is got

Then write code and calculate front to back ratio of the antenna in dB in horizontal plane.

Front=0;

Back=db_P(181);

FB=abs(Front-Back)

Then we can directly plot power as a function of the phi to find the number of antenna side lobes. The direction of maximum radiation and powers in dB radiated into direction of each side lobe in horizontal plane can be directly observed in the figures.

plot(phi_rad,db_P)

Step 5: Repeat steps for elevation angles

clear all

Phi= csvread(‘Phi.csv’);

P_phi= csvread(‘P_phi.csv’);

Theta= csvread(‘Theta.csv’);

P_theta= csvread(‘P_theta.csv’);

theta_rad=(Theta/180)*pi;

Maxnum=max(P_theta);

P_theta_n=P_theta/Maxnum;

h=polar_dB(theta_rad,P_theta_n,25);e Shengyu Xia: Number: MIT170811

  1. Introduction

In the field of antenna design, the term radiation pattern (or antenna pattern or remote field pattern) is a directed (Angle) dependence of the radio waves from the antennas or other sources. Especially in optical fibre, laser, and integrated optics field, the term radiation pattern can also be used as a synonym for near-field pattern or Fresnel. This involves the electromagnetic field in the source of the near field or the location of the area of the Fresnel dependencies. The near-field pattern is usually placed in front of the light plane or on the surface of the cylindrical or spherical that surrounded it defined on. In this report, we have used the numerical analysis methods to critically review and analyze mobile and satellite communication systems. At the same time, we also identify engineering techniques to solve problems related to antenna and GSM laboratories.

  1. Method

The angular variation of the radiation produced by an antenna is often mapped as a graphical representation called a “radiation pattern”. In fact, the radiation pattern is perhaps the most important characteristics of an antenna. The radiation pattern can be obtained by plotting the powers at different angles. The main formulas required for constructing radiation pattern is below:

(1)

 (2)

Now we give the detailed steps to show how to construct the radiation pattern by numerical method. We have 4 data files in .csv format that represent results for measured radiated power of an antenna versus azimuthal angle φ and elevation angle θ. File Phi.csv contains a column of azimuthal angles φ from 0-360 degrees. File P_phi.csv contains a column of measured radiated power in Watts in the direction of angle φ with matching index, e.g. fifth row in P_phi.csv (P(5) value) corresponds to fifth row in Phi.csv (φ(5) value). File Theta.csv contains a column of elevation angles θ from 0-360 degrees. File P_theta.csv contains a column of measured radiated powers corresponding to θ angles.

Step1: import files

First open the Matlab software and build a blank script, the code is attached in below. These matlab codes can import the values from the files into the variables.

clear all

Phi= csvread(‘Phi.csv’);

P_phi= csvread(‘P_phi.csv’);

Theta= csvread(‘Theta.csv’);

P_theta= csvread(‘P_theta.csv’);

Step 2: Preliminary parameter calculations

The first is to find the angle in direction of which radiation is maximum, we can use the max() function to find. Then convert the angles into radians and normalize the power by dividing the maximum power. The codes are below.

phi_rad=(Phi/180)*pi;

Maxnum=max(P_phi);

P_phi_n=P_phi/Maxnum;

Step 3: Plot antenna radiation pattern

We use “plot_dB.m” Matlab program to plot radiation pattern for powers in dB versus azimuthal angle φ. Since we have finished the preparation work, so the code is easy to work out as

polar_dB(phi_rad,P_phi_n,20,3);

The output picture can be easily exported by clicking save as button.

Step 4: Parameter calculations

First we write code to calculate P ratio in dB and calculate the beamwidth of the antenna in horizontal plane. The beamwidth is the range of angles within which amplitude falls to 0.707 of maximum level or power falls to 0.5 (or -3dB) of maximum level.

db_P=10*log(P_phi_n); % converting in to dB scale

[Maxdb,index]=max(db_P); % find the max dB

[Ldb,lindex]=find(abs(db_P+3) < 0.1); %find the 3dB below the max dB, then the beam width is got

Then write code and calculate front to back ratio of the antenna in dB in horizontal plane.

Front=0;

Back=db_P(181);

FB=abs(Front-Back)

Then we can directly plot power as a function of the phi to find the number of antenna side lobes. The direction of maximum radiation and powers in dB radiated into direction of each side lobe in horizontal plane can be directly observed in the figures.

plot(phi_rad,db_P)

Step 5: Repeat steps for elevation angles

clear all

Phi= csvread(‘Phi.csv’);

P_phi= csvread(‘P_phi.csv’);

Theta= csvread(‘Theta.csv’);

P_theta= csvread(‘P_theta.csv’);

theta_rad=(Theta/180)*pi;

Maxnum=max(P_theta);

P_theta_n=P_theta/Maxnum;

h=polar_dB(theta_rad,P_theta_n,25);

db_P=10*log(P_theta_n);

[Maxdb,index]=max(db_P);

[Ldb,lindex]=find(abs(db_P+3) < 0.1);

Front=0;

Back=db_P(181);

FB=abs(Front-Back)

figure

plot(theta_rad,db_P)

Step 6: Export result to a file

All these results can be saved into csv files.

  1. Results

db_P=10*log(P_theta_n);

[Maxdb,index]=max(db_P);

[Ldb,lindex]=find(abs(db_P+3) < 0.1);

Front=0;

Back=db_P(181);

FB=abs(Front-Back)

figure

plot(theta_rad,db_P)

Step 6: Export result to a file

All these results can be saved into csv files.

  1. Results

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