COMMS 4

Question 1

R (Parallel)

Answer 1

R= 1/(πaδσ_c )

Question 2

L (Parallel)

Answer 2

L= μ/π ln⁡〖d/a〗

Question 3

C (Parallel)

Answer 3

C=πϵ/ln⁡〖d/a〗

Question 4

G (Parallel)

Answer 4

G= σ/cosh^(-1)⁡〖d/2a〗

Question 5

σ

Answer 5

σ=1/ρ

Question 6

δ

Answer 6

δ=1/√πfμσ

Question 7

R (Coaxial)

Answer 7

R= 1/(2πδσ_c ) (1/a+1/b)

Question 8

L (Coaxial)

Answer 8

L= μ/2π ln⁡〖b/a〗

Question 9

C (Coaxial)

Answer 9

C=2πϵ/ln⁡〖b/a〗

Question 10

G (Coaxial)

Answer 10

G= (2σ_c)/cosh^(-1)⁡〖b/a〗
G= 2σ/ln⁡〖b/a〗

Question 11

CHARACTERISTICS IMPENDENCE (Z_O)

Answer 11

Z_(O=) √(((R+jωL))/((G+jωC) ))

Question 12

lossy line

Answer 12

Z_(O=) √(R/G)

Question 13

lossless line

Answer 13

Z_(O=) √(L/C)

Question 14

CHARACTERISTICS IMPENDENCE (Z_O) (PARALLEL LINE)

Answer 14

Z_(O=) 276/√k log 2S/d

Question 15

CHARACTERISTICS IMPENDENCE (Z_O) (COAXIAL CABLE)

Answer 15

Z_(O=) 138/√k log D/d

Question 16

Attenuation Constant (α)

Answer 16

α=R/(2Z_o ),Neper/m or dB/m

Question 17

Phase Shift Constant (β)

Answer 17

β=ω√LC,Rad/m or Deg/m
β=2π/λ,Rad/m or Deg/m

Question 18

Attenuation and Phase Constant

Answer 18

γ=α+jβ=√((R+jωL)+(G+jωC) )
where: α is in Neper/Km,β is in Rad/Km

Question 19

Velocity Propagation (V_p)

Answer 19

V_p=λf
V_p=ω/β=2πf/β
V_p=V_C/√k
V_p=V_c*Vf in or medium

Question 20

Velocity Factor

Answer 20

Vf=V_P/V_C ;Vf=1/√k

Question 21

REFLECTION COEFFICIENTS

Answer 21

Γ=e_reflected/e_incident ; Γ=e^-/e^+

Question 22

Load &Characteristic Impedance (RC)

Answer 22

Γ=(Z_L-Z_O)/(Z_L+Z_O )

Question 23

Reflected & Incident Power (RC)

Answer 23

Γ=√(P_ref/P_inc )

Question 24

Reflected & Incident Signal (RC)

Answer 24

Γ=e_ref/e_inc =Γ=I_ref/I_inc

Question 25

Reflected & Incident Signal (SWR)

Answer 25

SWR=(V_inc+V_ref)/(V_inc-V_ref ) = (I_inc+I_ref)/(I_inc-I_ref )

Question 26

Transmission Line Voltage Measurement (SWR)

Answer 26

SWR=V_max/V_min =e_max/e_min =I_max/I_min

Question 27

Load &Characteristic Impedance (sWR)

Answer 27

SWR=Z_L/Z_O ifZ_L>Z_0
SWR=Z_O/Z_L ifZ_O>Z_L

Question 28

Reflected & Incident Power (SWR)

Answer 28

SWR =(1+√(P_ref/P_inc ))/(1-√(P_ref/P_inc ))

Question 29

RELATIONSHIP BETWEEN SWR AND Γ (SWR)

Answer 29

SWR =(1+Γ)/(1-Γ)

Question 30

RELATIONSHIP BETWEEN SWR AND Γ (Γ )

Answer 30

Γ =(SWR-1)/(SWR+ 1)

Question 31

RETURN LOSS/ REFLECTION LOSS

Answer 31

R_L=1/Γ;R_(L (dB))=-20logΓ

Question 32

TRANSMISSION LOSS (SWR)

Answer 32

T_LdB=-10log[1-(SWR-1)/(SWR+1)]^2

Question 33

TRANSMISSION LOSS (Γ)

Answer 33

T_LdB=-10log[1-Γ]^2

Question 34

TRANSMITTTED POWER

Answer 34

P_abs=P_inc-P_ref
P_abs=P_inc (1-Γ^2 )

Question 35

TIME DELAY

Answer 35

t_d=√LC
t_d=1.016√k

Question 36

PHASE SHIFT

Answer 36

θ=(360t_d)/T
T=1/f

Question 37

CABLE ATTENUATION

Answer 37

attenuation= dB/100ft

Question 38

INPUT IMPEDANCE

Answer 38

Z_in=Z_o [(Z_L+jZ_o tanβl)/(Z_o+jZ_L tanβl)]

Question 39

ELECTRICAL LENGTH

Answer 39

βl°=(360°l)/λ;βl_rad=ωl/λ

Question 40

l=λ/4

Answer 40

Z_in=(Z_o^2)/Z_L ;Z_o=√(Z_in ) Z_L

Question 41

l=λ/2

Answer 41

Z_in=Z_L

Question 42

Z_L=∞

Answer 42

Z_in=-jZ_o cotβl

Question 43

Z_L=0

Answer 43

Z_in=jZ_o tanβl

Question 44

Z_L=Z_O

Answer 44

Z_in=Z_o