Medium distance Microwave Communication system for Aircraft

Microwaves are a type of electromagnetic radiation with wavelengths ranging from one meter to one millimeter and frequencies ranging from 300 MHz to 300 GHz and frequencies ranging from 300 MHz to 300 GHz and frequencies ranging from 300 MHz to 300 GHz and frequencies ranging from 300 MHz to 300 GHz and frequencies ranging from 300 MHz to 300 GHz and frequencies ranging from 300 MHz to 300 GHz and frequencies ranging from 300 (1 mm). Microwaves travel in a straight line, unlike lower frequency radio waves, and do not diffract over hills, follow the earth's surface as ground waves, or reflect off the ionosphere, limiting terrestrial migration. Because microwave components propagate beyond the line of sight via changing electromagnetic fields rather than current in the conductor or voltage across two places, repeater stations must be spaced at roughly 40km intervals.

Microwave relay system

Microwave radio relay was a popular technology in the 1950s and 1960s for transferring communications such as long-distance phone calls and television programs between two terrestrial places using a narrow beam of microwaves. Microwaves are sent between relay stations using directional antennas on a line-of-sight path, forming a fixed radio link.

Important terms for link budget design of microwave link

A connection budget is an accounting of all the power gains and losses experienced by a communication signal as it travels from the transmitter to the receiver over a communication channel such as radio waves, cable, waveguide, or optical fiber in a telecommunication system. It's a formula that uses the transmitter power to determine the acquired power.

Microwaves and power

Antenna gain is extraordinarily high due to the capacity to focus microwave signals into tight beams. A flashlight's reflector produces a narrow beam of light that may illuminate faraway objects, while antenna gain boosts a microwave signal's effective-radiated power. By bouncing the signal off a parabolically curved reflecting surface, the most famous microwave antenna concentrates the signal.

Antenna Gain

The difference between the power transmitted by an antenna in one direction and the power transmitted by an isotropic antenna in the same direction is known as antenna gain. The maximum signal intensity that an antenna may emit or receive in a particular direction is defined by this specification. As a result, antennas boost gain by concentrating the signal over a smaller area. For example, an omnidirectional antenna sends and receives signals. In electromagnetics, an antenna's power gain, or simply gain, is a significant performance figure that combines the antenna's directivity and electrical efficiency. A transmitting antenna's gain describes how successfully it transforms signals.

radio waves that are directed in a specific direction are given power. A transmitting antenna's gain describes how successfully it transforms radio waves from a certain source.

EIRP (Effective Isotropic Radiated Power)

EIRP is the calculated radiated power of an antenna in a specific direction. This is the output power when the Antenna compresses a signal into a smaller area. Transmission line losses, connection losses, and antenna gain will all be factored into the EIRP. It's the power input to the transmitter's antenna multiplied by the isotropic antenna gain. ERP is a measurement of the transmitter's power output and the antenna's ability to direct it in a certain direction. It's calculated by multiplying the antenna's gain by the antenna's input power. It is a unit of measurement used in electronics and telecommunications, particularly in broadcasting, to determine a broadcasting station's apparent strength as experienced by listeners in its reception area.

Fade Margin

Allowance in the design that allows for adequate device benefit or sensitivity to tolerate anticipated fading while maintaining the required degree of service quality.

The maximum amount by which a received signal level can be reduced without the device's output falling below a predetermined threshold. It is most commonly used to describe a communication equipment, such as a satellite. In telecommunication, the term fade margin has the following definitions: Allowance in design that allows for adequate device benefit or sensitivity to accommodate predicted fading while preserving service quality.

Received Signal Level (dBm) – Receiver Sensitivity = Fade Margin (dB) (dBm)

Receiver Sensitivity

In a receiver, sensitivity is typically defined as the minimum input signal required to produce a particular output signal with a specified signal-to-noise (S/N) ratio, and is defined as the minimum signal-to-noise ratio times the mean noise power, as shown in equation. The sensitivity of a signal impinging on the antenna (at the system level) is known as minimal operational sensitivity (MOS), as shown in equation. MOS can be stated in dB Li because it contains antenna gain (dB referenced to a linear isotropic antenna). The minimum pulse width at which the specified sensitivity applies must also be mentioned when specifying the sensitivity of receivers intended to capture and analyze pulse signals. For more information on the importance of minimum pulse width in receiver design, see Section 5-2's discussion of post detection bandwidth (B). The sensitivity of a receiver is the lowest signal strength it can detect. It denotes the smallest signal a receiver can detect and analyze. The receiver's sensitivity is measured in decibels (dBm). To calculate receiver sensitivity, the noise floor is multiplied by the receiver's total noise statistic. This is how the noise floor at the demodulator's input is measured.

Fresnel zone

A Fresnel zone is a confocal prolate ellipsoidal area of space that exists between and around a transmitter and a receiver. If there are obstructions or reflective artifacts between the transmitter and the receiver, radio, sound, or light waves may take slightly different paths before reaching the receiver. Because of this, the waves will arrive at slightly different times and be slightly out of phase. The waves will intervene constructively or destructively depending on the magnitude of the phase change. At any given distance from the transmitter and receiver, the size of the measured Fresnel zone can be used to predict whether obstructions or discontinuities in the route would cause significant interference.

Noise threshold

In signal theory, the noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals within a measurement system, where noise is defined as any signal other than the one being monitored.

In radio communication and electronics, this may include thermal noise, black body, cosmic noise as well as atmospheric noise from distant thunderstorms and similar and any other unwanted man-made signals, sometimes referred to as incidental noise. The noise floor is the measure of the signal generated by adding all of the noise sources and unwanted signals within a measurement system, where noise is characterized as any signal other than the one being monitored in signal theory. Thermal noise and noise produced by circuits inside the receiver can decide the performance of the noisy receiver.

The fading effect must be considered when developing microwave radio links, which can be on a per hop or device basis. Noise levels are set not to surpass a certain percentage of the time in the device design, such as 1%,

0.1 percent, and so on, or noise must be less than a certain value, such as 99 percent, 99.99 percent, and so on. In more practical terms, this means that the device will not be able to fulfill the necessary requirements for 8.8 hours per year if a 99.9% path reliability is considered.

MATLAB code and result

clc close all clear all

%defining variables

N = 8; % N value is Number we taken d_km = 40;

%distance between two planes cable_loss_tx = 1;

%Transmitting cable loss (1) dB cable_loss_rx = 1;

%Receiving cable loss (1) dB

fc = (0.9 + (N*0.05)); %Carrier frequency Gt

= 1.1; %Transmitting antenna gain in dBi

Gr = 1.2; %Receiving antenna gain in dBi N_fig = 8; %Receiver noise figure rec_BW

= 60*10^3; %Receiver bandwidth Tempr = 243; %Ambient temperature

k_bol_cons=1.3803*10^-23; % Boltzman constant J/K fade_mar = 19; %Fade margin

C_N_ratio = 17; %Receiver SNR (18~20) dB

% free space path loss L_dB_km=92.4+20*log10(fc)+20*log10(d_km);

% noise threshold at the output end of the receiver N_thres_dBW=10*log10(k_bol_cons*Tempr*rec_BW)+N_fig;

%Received power sensitivity Pr_sen_dB = C_N_ratio + N_thres_dBW;

%Calculating the EIRP

EIRP_dBW = Pr_sen_dB + (L_dB_km+fade_mar) - Gr + cable_loss_rx;

%Calculating the Transmit power

Pt = EIRP_dBW + cable_loss_tx - Gt; %in dBW Pt_abs = 10^(Pt/10); %in watt

%link budget LB1=Pt;

LB2=LB1-cable_loss_tx; LB3=EIRP_dBW;

LB4=LB3-L_dB_km-fade_mar; LB5=LB4+Gr;

LB6=LB5-cable_loss_rx; LB7=C_N_ratio;

Link_Budget=[LB1 LB2 LB3 LB4 LB5 LB6 LB7];

plot(Link_Budget); xlabel('distance') ylabel('Powerlevel (dbm)')

grid on

%displaying the results

disp(['EIRP = ', num2str(EIRP_dBW)]); disp(['Antenna Gain = ', num2str(Gt)]); disp(['Free-Space-Loss = ', num2str(L_dB_km)]);

disp(['Fading Margin = ', num2str(fade_mar)]); disp(['Receiver Sensitivity = ', num2str(Pr_sen_dB)]); disp(['Noise Figure = ', num2str(N_fig)]); disp(['Transmit Power (in watts) = ', num2str(Pt_abs)]);

%Part 2 (doubling the distance) disp('After doubling the distance: ');

d_km_new = d_km*2; %doubling the distance

%new free space loss L_dB_km_new=92.4+20*log10(fc)+20*log10(d_km_new);

%new fade margin

fade_mar_new = EIRP_dBW - Pr_sen_dB - L_dB_km_new + Gr - cable_loss_rx;

%displaying the new values disp(['New distance = ', num2str(d_km_new)]); disp(['New free-space-loss = ', num2str(L_dB_km_new)]);

disp(['New fade margin = ', num2str(fade_mar_new)]);

Output

EIRP = 11.8085

Antenna Gain = 1.1

Free-Space-Loss = 127.963 Fading Margin = 19

Receiver Sensitivity = -134.7545 Noise Figure = 8

Transmit Power (in watts) = 14.1531 After doubling the distance:

New distance = 100

New free-space-loss = 133.9836 New fade margin = 12.9794

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