A section of a parallel-plate air waveguide with a plate separation of 7.11 mm is constructed to be used at 15 GHz as an evanescent wave attenuator to attenuate all the modes except the TEM mode along the guide. Find the minimum length of this attenuator needed to attenuate each mode by at least 100 dB. Assume perfect conductor plates.

Answers

Answer 1

Answer:

the required minimum length of the attenuator is 3.71 cm

Explanation:

Given the data in the question;

we know that;

[tex]f_{c_1[/tex] = c / 2a

where f is frequency, c is the speed of light in air and a is the plate separation distance.

we know that speed of light c = 3 × 10⁸ m/s = 3 × 10¹⁰ cm/s

plate separation distance a = 7.11 mm = 0.0711 cm

so we substitute

[tex]f_{c_1[/tex] = 3 × 10¹⁰ / 2( 0.0711  )

[tex]f_{c_1[/tex] = 3 × 10¹⁰ cm/s / 0.1422  cm

[tex]f_{c_1[/tex] =  21.1 GHz which is larger than 15 GHz { TEM mode is only propagated along the wavelength }

Now, we determine the minimum wavelength required

Each non propagating mode is attenuated by at least 100 dB at 15 GHz

so

Attenuation constant TE₁ and TM₁ expression is;

∝₁ = 2πf/c × √( ([tex]f_{c_1[/tex] / f)² - 1 )

so we substitute

∝₁ = ((2π × 15)/3 × 10⁸ m/s) × √( (21.1 / 15)² - 1 )

∝₁ = 3.1079 × 10⁻⁷

∝₁ = 310.79 np/m

Now, To find the minimum wavelength, lets consider the design constraint;

20log₁₀[tex]e^{-\alpha _1l_{min[/tex] = -100dB

we substitute

20log₁₀[tex]e^{-(310.7np/m)l_{min[/tex] = -100dB

[tex]l_{min[/tex] = 3.71 cm

Therefore, the required minimum length of the attenuator is 3.71 cm


Related Questions

A certain organ pipe, open at both ends, produces a fundamental frequency of 288 Hz in air. Part A If the pipe is filled with helium at the same temperature, what fundamental frequency tHe will it produce

Answers

Answer:

773.25 Hz

Explanation:

Concept : In an open organ pipe in fundamental mode of vibration

wave length of wave λ = 2L

where L  is length of  the pipe

frequency   = velocity of sound / λ

Given values: fundamental frequency = 288 Hz

fluid is air. velocity of sound = 340 m/s

⇒ 288 = 340/2L

⇒L = 59.02 cm

The point to be noted is if the pipe is filled with helium initially at the same temperature, there would be change in the sound velocity .Then,  frequency of note produced will also be changed .

We know that velocity of sound is inversely proportional to  square root of molar mass of gas

velocity of sound in air / velocity of sound in helium = Square root of (Molar mass of Helium/ molar mass of air)

[tex]\frac{V_a}{V_{He}} = \sqrt{\frac{4}{28.8} } \\\frac{340}{V_{He}} =0.3725\\V_{He} =912.5 m/s[/tex]

Now, frequency  = velocity of sound / λ

= 912.75 / (2 x 0.5902)

= 773.25 Hz

A spherical conducting shell has an inner radius of 0.2 m and an outer radius of 0.4 m. There is no charge on the outer surface but the shell does have a nonzero net charge. All charges remain at rest. The potential at the outer surface is -2 V. The potential at the center of the cavity is g

Answers

Answer:

[tex]P_c=-4v[/tex]

Explanation:

From the question we are told that:

Inner radius [tex]r_1=0.2[/tex]

Outer radius[tex]r_2=0.4[/tex]

Potential at the outer surface is [tex]P_o= -2 V[/tex]

Generally the equation for Potential at the outer surface P_o  is mathematically given by

[tex]P_o=\frac{KQ}{r_2}[/tex]

[tex]-2=\frac{KQ}{0.4}[/tex]

Therefore

[tex]KQ=-0.8v[/tex]

Generally the equation for Potential at Center of outer cavity [tex]P_c[/tex]  is mathematically given by

[tex]P_c=\frac{KQ}{r_1}[/tex]

[tex]P_c=\frac{-0.8}{0.2}[/tex]

[tex]P_c=-4v[/tex]

Therefore the potential at the center of cavity

[tex]P_c=-4v[/tex]

The potential at the center of the cavity of the spherical conducting shell is -0.4 V.

What is electric potential of spherical shell?

Electric potential of spherical shell is the total amount of work required to move a charge in s spherical shell from one point to other.

Electric potential of spherical shell at outer surface can be given as,

[tex]P_{outer}=k\dfrac{Q}{r_o}[/tex]

Electric potential of spherical shell at center of outer gravity can be given as,

[tex]P_{cavity}=k\dfrac{Q}{r_i}[/tex]

Here, (Q) is the charge, (k) is the constant and [tex](r_o, r_i)[/tex] is the outer and inner radius.

A spherical conducting shell has an outer radius of 0.4 m and the potential at the outer surface is -2 V. Thus, the potential at the outer surface can be find out using the above formula as,

[tex]-2=k\dfrac{Q}{0.4}\\kQ=-0.8\rm V[/tex]

The spherical conducting shell has an inner radius of 0.2 m. Thus, the potential at the outer surface can be find out using the above formula as,

[tex]P_{cavity}=k\dfrac{Q}{0.2}\\P_{cavity}=\dfrac{-0.8}{0.2}\\P_{cavity}=-0.4\rm V[/tex]

Thus, the potential at the center of the cavity of the spherical conducting shell is -0.4 V.

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The illustration shows ?
A)open circuit
B)broken circuit
C)series circuit
D)parallel circuit

Answers

Answer:

D)parallel circuit

Explanation:

the components are placed parallel from eachother

D. Parallel circuit

A cannonball is shot from the top of a
47.8 m high hill at a speed of 53.7 m/s.
How fast is it going when it reaches
the plain below?

Answers

Answer:

61.8

Explanation:

It must be going at a speed of 61.81 m/s when it reaches the plain below

What are  kinematic equations?

The kinematic equations are a set of equations that describe the motion of an object with constant acceleration. Kinematics equations require knowledge of derivatives, rate of change, and integrals.

using  Kinematics equations

[tex]v^{2}[/tex] = [tex]u^{2}[/tex] + 2gs                         ( a = g)

   = [tex](53.7)^{2}[/tex] + 2 * 9.8 * 47.8 m

 v  = 61.81 m/s

It must be going at a speed of 61.81 m/s when it reaches the plain below

learn more about Kinematics equations

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what happen to the total energy of a moving object if all the applied forces are conserved​

Answers

Answer:

As objects move around over time, the energy associated with them—e.g., kinetic, gravitational potential, heat—might change forms, but if energy is conserved, then the total will remain the same. Conservation of energy applies only to isolated systems.

thenks and pls mark me barinliestt :))

A sphere has a surface uniformly charged with 3.30 C. At what distance from its center is the potential 4.50 MV

Answers

Answer:

r = 6.6 x 10³ m = 6600 m

Explanation:

The potential at a distance from a charged sphere can be given as follows:

[tex]V = \frac{kq}{r}\\\\r = \frac{kq}{V}[/tex]

where,

r = distance = ?

k = Colomb Constant = 9 x 10⁹ Nm²/C²

q = charge on sphere = 3.3 C

V = potential = 4.5 MV = 4.5 x 10⁶ V

Therefore,

[tex]r = \frac{(9\ x\ 10^9\ Nm^2/C^2)(3.3\ C)}{4.5\ x\ 10^6\ V}[/tex]

r = 6.6 x 10³ m = 6600 m

List some distinguishing features of metamorphic rocks?

Answers

Answer:

Metamorphic rocks were once igneous or sedimentary rocks, but have been changed (metamorphosed) as a result of intense heat and/or pressure within the Earth's crust. They are crystalline and often have a “squashed” (foliated or banded) texture.

Explanation:

:)

PLS HELP!! Our eyes perceive colors because of differences in which of the following properties of light?


Amplitude


Brightness


Wavelength


Source

Answers

i think its wavelength correct me if i'm wrong

Answer:

Your answer is wavelength

is it possible to have rainbows during the fine sunny day? Explain your answer.​

Answers

Answer:

As long as there is rain, a rainbow is possible. Rain is possible on a sunny day, and is known as a sunshower.The rainbow can be observed in a sunny day if the water droplets are present in air and the sun rays pass through it reaches the eye of the observer. In this situation, the observer can see a rainbow.

or

If you happened to look up at the sky this past weekend, you might have noticed a rare and beautiful sight: iridescent rainbow clouds, but not a drop of rain in sight. This phenomenon is known, fittingly, as cloud iridescence or irisation. The effect is not unlike seeing a rainbow painted on the clouds.

8. Which of Newton’s Laws would allow a passenger to fly right out of their seat if they do not have a seat belt on and a
car suddenly stops.
A) The First Law C) The Third Law
B) The Second Law D) The Fourth Law

Answers

The answer is A The first law

Why do we never notice quantization?
a. because the fundamental quanta are so large
b. because the fundamental quanta are so small
C. because we are moving quickly relative to such objects
d because we are moving slowly relative to such objects

Answers

Answer:

B

Explanation:

quantization of energy is only seen in atoms

Suppose you have a 6.0 V motorcycle battery that can move 3,000 C of charge. How much energy does it deliver

Answers

Answer:

1.8*10^4 Joules

Explanation:

Given data

Voltage= 6volts

Q= 3000 C

We know that the energy due to a point charge is

Pe= QV

substitute

Pe= 3000*6

Pe=18000

Pe= 18000Joules

Pe= 1.8*10^4 Joules

How long does it take for a 3.5 kW electric water heater to heat 40 kg of water? from 20 ° C to 75 ° C? The specific heat capacity of water is 4190 J/kgK PLEASE HURRY ITS A TEST​

Answers

Answer:

2633.7 s

Explanation:

From the question,

Heat lost by the water heater = Heat gained by the water

Applying,

P = cm(t₂-t₁)/t.................. Equation 1

Where P = power of the heat, c = specific heat capacity of water, m = mass of water, t₁ = initial temperature, t₂ = final temperature, t = time

make t the subject of the equation

t = cm(t₂-t₁)/P.............. Equation 2

From the question,

Given: c = 4190 J/kgK, P = 3.5 kW = 3500 W, m = 40 kg, t₁ = 20°C, t₂ = 75°C

Substitute these values into equation 2

t = 4190×40(75-20)/3500

t = 9218000/3500

t = 2633.7 s

What is the acceleration of a car going from a starting speed of 12 m/s to 25 m/s in 6 seconds? *​

Answers

Answer:

[tex]v = u + at \\ 25 = 12 + a6 \\ 13 = 6a \\ a = 2.16 \\ [/tex]

a=2.16ms^-2

1-The amount of heat required to raise the temperature
of 1 g of a substance by degree celsius is
one​

Answers

Answer:

• specific heat

1 Answer. The specific heat is the amount of heat required to raise the temperature of 1 g of substance by one degree Celsius or one Kelvin

the process where water vapor into the atmosphere is changed back into liquid water

Answers

Answer:

Condensation is the process by which water vapor in the air is changed into liquid water. Condensation is crucial to the water cycle because it is responsible for the formation of clouds.

Explanation:

just is

Write the differential equation that governs the motion of the damped mass-spring system, and find the solution that satisfies the initial conditions specified. Units are mks;
????
is the damping coefficient, with units of kg/sec.

m

Answers

This question is incomplete, the complete question  is;

Write the differential equation that governs the motion of the damped mass-spring system, and find the solution that satisfies the initial conditions specified. Units are mks; γ is the damping coefficient, with units of kg/sec

m = 0.2, γ = 1.6 and k = 4

Initial displacement is 1 and initial velocity is -2

x" + _____ x' ____x = 0

x(t) =

Answer:

the solution that satisfies the initial conditions specified is;

x(t) = [tex]c_1e^{-4t}cos(2t)[/tex] + [tex]c_2e^{-4t}sin(2t)[/tex]

Explanation:

Given the data in the question ;

m = 0.2, γ = 1.6, k = 4

x(0) = 1, x'(0) = -2

Now, the differential equation that governs the motions of spring mass system is;

mx" + γx' + kx = 0

so we substitute

0.2x" + 1.6x' + 4x = 0

divide through by 0.2

x" + 8x' + 20x = 0

hence, characteristics equation will be;

m² + 8m + 20 = 0

we find m using; x = [ -b±√(b² - 4ac) ] / 2a

m = [ -8 ± √((8)² - 4(1 × 20 )) ] / 2(1)

m = [ -8 ± √( 64 - 80 ) ] / 2

m = [ -8 ± √-16 ) ] / 2

m = ( -8 ± 4i ) / 2

m = -4 ± 2i

Hence, the general solution of the differential equation is;

x(t) = [tex]c_1e^{-4t}cos(2t)[/tex] + [tex]c_2e^{-4t}sin(2t)[/tex]

From the initial conditions;

c₁ = 1, c₂ = 1

the solution that satisfies the initial conditions specified is;

x(t) = [tex]c_1e^{-4t}cos(2t)[/tex] + [tex]c_2e^{-4t}sin(2t)[/tex]

HELP PLZ


Calculate the resistivity of a metal of length 2m at 20°C having the resistance

of 20 ohm and diameter 0.3mm?​

Answers

Answer:

40*C

Explanation:

Which of the following means that an
image is real?
A. +do
B. +di
c. -di
D.-do

Answers

Answer:

B

Explanation:

im paying on my phone but dont have full access when i log into computer

Answers

Answer:

um let me know what i can do to try get you full access

Explatnation:

7) The coefficient of performance (COP) of a refrigerator is defined as the ratio of A) the heat removed from the inside to the heat expelled (dismissed) to the outside. B) the heat expelled (dismissed) to the outside to the heat removed from the inside. C) the heat removed from the inside to the work done to remove the heat. D) the heat expelled (dismissed) to the outside to the work done to remove the heat

Answers

Answer:

C) the heat removed from the inside to the work done to remove the heat.

Explanation:

Refrigerator is a heat engine working in reverse direction . Heat from cold source is taken out , some work is done to remove them and total heat and work energy is thrown into outside surrounding .

If q heat is taken out and W is work done to get this heat out .

coefficient of performance ( COP ) = q / W .

Hence C ) is the right choice .

A system has two possible energy states, E0 and E1 (with E1 > E0). If the difference between these energy states grows (E0 and E1 get further apart while the temperature stays constant), then the ratio of the number of particles in state E0 over the number of particles in state E1 will:__________

Answers

Answer:

The number of particles in state E0 over the number of particles in state E1  will reduce

Explanation:

E0 represents the ground level state when all the particles have same energy level.

E1 represents excited state in which only a few particle reaches

E0 and E1 get further apart  means that the energy difference between the two level increases.

Thus, the number of particles in state E0 over the number of particles in state E1  will reduce.

The springs of a 1500 kg car compress 5.00 mm when its 68 kg driver gets into the driver's seat. Part A If the car goes over a bump, what will be the frequency of oscillations

Answers

Answer:

the frequency of the oscillation is 1.5 Hz

Explanation:

Given;

mass of the spring, m = 1500 kg

extention of the spring, x = 5 mm = 5 x 10⁻³ m

mass of the driver = 68 kg

The weight of the driver is calculated as;

F = mg

F = 68 x 9.8 = 666.4 N

The spring constant, k, is calculated as;

k = F/m

k = (666.4 N) / (5 x 10⁻³ m)

k = 133,280 N/m

The angular speed of the spring is calculated;

[tex]\omega = \sqrt{\frac{k}{m} } \\\\\omega = \sqrt{\frac{133280}{1500} } = 9.426 \ rad/s[/tex]

The frequency of the oscillation is calculated as;

ω = 2πf

f = ω / 2π

f = (9.426) / (2π)

f = 1.5 Hz

Therefore, the frequency of the oscillation is 1.5 Hz

Why does carpet produce static electricity more than hardwood floors?

Answers

Answer:

The carpet has a buildup of electrons in it that get released onto your body when you rub across the floor while the hardwood doesn't have electrons built up inside of it.

Explanation:

I study that

Carpet produce more static electricity because the rubbing on the carpet release negative charge, called electrons, which can build up on one object to produce a static charge. For example, when you shuffle your feet across a carpet, electrons can transfer onto you, building up a static charge on your skin.

on what factors, current sensitivity voltage sensitivity of
a galvanometer depend?

Answers

Explanation:

The voltage sensitivity of  a galvanometer is given by :

[tex]\dfrac{NBA}{RK}[/tex]

Where

N=Number of turns

A=Area of coil

B=Magnetic field produced in coil

K=Torsion constant of galvanometer

R=Resistance of galvanometer

The current sensitivity of  a galvanometer is given by :

[tex]\dfrac{NBA}{K}[/tex]

Hence, this is the required solution.

The diagram below shows a person swinging a hammer.

Which position has the least amount of kinetic energy?

A-1
B-2
C-3
D-4


Answers

4 because its not yet moving. It has kinetic energy, it just hasn’t been used yet.

Radon has a half-life of 56s. After what time will it's activity be reduced to (a) 90% (b) 50% (c) 10% of it's initial value​

Answers

Answer:

A) 11.2 s

B) is 56 s

C) 170.8 s

A woman is 160160cm tall. What is the minimum vertical length of a mirror in which she can see her entire body while standing upright

Answers

This question is incomplete, the complete question is;

A woman is 160cm tall. What is the minimum vertical length of a mirror in which she can see her entire body while standing upright.

Hint: Consider the ray diagram below, of the rays that enable her to see her feet and the top of her head.

Use what you know about the law of reflection, together with a bit geometry.

The missing Image is uploaded along this answer below.

Answer:

the minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm

Explanation:

Given the data in the question and illustrated in the image below,

From image 2;

The distance from the woman's eyes to the top of her head is represented as b and a represent the distance from her eyes to her feet.

Therefore, since her height is 160 cm

a + b = 160 ------ let this be equation 1

i.e AD + DG = 160 cm

Now, from the same image 2, we will notice that triangle ABC and tringle CBD are similar, so

∠ABC = ∠CBD

AC = CD

since AD = a and AC + CD = A

AC = CD = a/2

Also, triangle DEF and FEG are si,ilar

∠DEF = ∠FEG

so

DF = FG

since DG = b and DF + FG = b

DF = b/2

so the minimum vertical length of a mirror in which the woman can see her entire body while standing upright will be;

⇒ a/2 + b/2  

⇒ a + b / 2

from equation 1, a + b = 160

so

⇒ a + b / 2 = 160 / 2 = 80

Therefore, the minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm

The minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm.

What is the minimum vertical length?

The minimum vertical length of a mirror in which she can see her entire body while standing upright is calculated as follows;

u + v = 160 cm

where;

u is the image heightv is the object height

For mirror, u = v

2u = 160 cm

u = 160 cm/2

u = 80 cm

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Use the drop-down menus to complete each sentence.

The number of half-lives changes. This is the _______ variable.

The number of radioactive atoms changes due to the number of half-lives. The number of radioactive atoms is
therefore the _______
variable.

Answers

Answer:

Independent, then dependent

Explanation:

Just took this on Edge 2021

Consider a 30-cm-diameter hemispherical enclosure. The dome is maintained at 600 K, and heat is supplied from the dome at a rate of 65 W while the base surface with an emissivity of 0.55 is maintained at 400 K. Determine the emissivity of the dome.

Answers

Answer:

[tex]\epsilon_2=0.098[/tex]

Explanation:

Diameter [tex]d=30cm=0.3m[/tex]

Temperature [tex]T=600k[/tex]

Rate of supply [tex]r=65W[/tex]

Emissivity of base surface [tex]\in_b =0.55[/tex]

Temperature at base [tex]T_b=400k[/tex]

Generally the equation for Area of base surface is mathematically given by

 [tex]A_b=\frac{\pi}{4}d^2[/tex]

 [tex]A_b=\frac{\pi}{4}0.3^2[/tex]

 [tex]A_b=0.0707m^2[/tex]

Generally the equation for Area of Hemispherical dome is mathematically given by

 [tex]A_h=\frac{\pi}{2}d^2[/tex]

 [tex]A_h=\frac{\pi}{2}0.3^2[/tex]

 [tex]A_h=0.1414m^2[/tex]

Since base is a flat surface

 [tex]F_{11}+F_{12}=1[/tex]

 [tex]F_{11}=0[/tex]

Therefore

 [tex]F_{12}=1[/tex]

 [tex]A_b=0.0707m^2[/tex]

Generally the equation for Net rate of radiation heat transfer between two surfaces is mathematically given by

 [tex]Q_{21}=-Q_{12}[/tex]

 [tex]Q_{21}=\frac{\sigma(T_1^4-T_2^4)}{\frac{1-\epsilon}{A_b\epsilon_1} +\frac{1}{A_bF_{12}} +\frac{1-\epsilon_2}{A_h*\epsilon_2} }[/tex]

Where

 [tex]\sigma=5.67*10^{-8}[/tex]

Therefore

  [tex]65=\frac{(5.67*10^{-8}(400^4-600^4))}{\frac{1-0.55}{0.0707*0.55}+\frac{1}{0.0707}+\frac{1-\epsilon_2}{0.1414*\epsilon_2}}[/tex]

 [tex]\epsilon_2=0.098[/tex]

 [tex]\epsilon_2 \approx 0.1[/tex]

Therefore  the emissivity of the dome is

 [tex]\epsilon_2=0.098[/tex]

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