A resonant six-turn loop of closely spaced turns is operating at 50 MHz. The radius of the loop is λ/30, and the loop is connect
ed to a 50-ohm transmission line. The radius of the wire is λ/300, its conductivity is σ = 5.7 × 107 S/m, and the spacing between the turns is λ/100. Determine the:
a. the directivity of the antenna (in dB)
b. radiation efficiency taking into account the proximity effects of the turns
c. reflection efficiency gain of the antenna (in dB)
a. the directivity of the antenna (in dB)
b. radiation efficiency taking into account the proximity effects of the turns
c. reflection efficiency gain of the antenna (in dB)
1 answer:
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Answer:
a)
b) %
Explanation:
A) First, let's write the energy balance:
(The enthalpy of an ideal gas is just function of the temperature, not the pressure).
The Cp of air is: 1.004 And its specific R constant is 0.287
.
The only unknown from the energy balance is , so it is possible to calculate it. The power must be negative because the work is done by the fluid, so the energy is going out from it.
B) The isentropic efficiency (e) is defined as:
Where is the isentropic enthalpy at the exit of the turbine for the isentropic process. The only missing in the last equation is that variable, because
can be obtained from the energy balance
An entropy change for an ideal gas with constant Cp is given by:
You can review its deduction on van Wylen 6 Edition, section 8.10.
For the isentropic process the equation is:
Applying logarithm properties:
Then,
So, now it is possible to calculate :
Finally, the efficiency can be calculated:
%
Answer:
Detailed working is shown
Explanation:
The attached file shows a detailed step by step calculation..
