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L») 3L0"? EL") %(DA E— _f_ ‘7‘“: HQ“: p.183 d~~h,. D, 94mg, YA?“ ‘U "N BB 713  Spring Quarter 2004
Final Exam June 7th, 2004 Write your name below and sign the honor pledge “No aid given, received, or observed” if it
applies. There are 3 problems on this exam. Exam is open book and notes.
Please box or underline your ﬁnal answers, and remember to include units.
Be sure to show all work clearly if you wish to obtain any partial credit. Try to keep your work within the provided space. Use the back of a previous sheet
if necessary. Name:
No aid given, received, or observed. “The Pledge”: BMW A 1 GHz transmitter is located 40 m above the leftmost point on the terrain proﬁle shown on
the next page. A likepolarized receiver is located at the rightmost point on the proﬁle (52 km
away), and the propagation loss relative to free Space is measured as the receiver height is increased from ground level.
(a) What is the lowest receiver height for which a free space propagation level should be obtained
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m A and assume a planar Earth. P Electron densitv (#/m3) (a) Find electron density values N1 and N 2 to make this electron density proﬁle consistent with
the given ionogram for the ordinary wave. Note the charge and mass of an electron are 1.6 x10’19 c and 9.1 x10‘31 kg, and so = 8.854 x 10'12 F/m. (15 points). 0"an W nilW) win Kt} .= ‘5”: 1. L
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3138c ‘3 in“ A series of transmission curves for ﬁxed oblique operating frequency f o b = 12 MHz but varying path distances D are now overlaid on the ionogram as shown below. 400 4 350:}. ..... ...... ..... ...... ...... ..... ...... ..... ..... ...... ..... . . . . . . . . i . . . . . . , . . . . . . . . . . . . . . l l 4 l . . . . . . . . i . i . l l . . . . . l l l .  . . . . l . . . . . . .  . . . i . . I . . . . . . . . . . . i x . l N
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E)? “\ka Vertical Frequency (MHz) (blhndthe skip distance for this case. (10 points)
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W pvi‘éc " h D (c) Find an angle 6, that can be used to communicate over a 1100 km path at 12 MHz. (10 points) 594,61 : Sgt
V II WOSUAM operates at 82% 3H2 and broadcasts 5 kW of power from a short vertical dipole
antenna on the ground. The entral Ohio region can be modeled as having an average eﬂ‘ective
conductivity of 12 millimhos and an effective dielectric constant of 5. (a) Find the distance in km within which the planar Earth groundwave theory is applicable for pre
dicting the signal strength of this station. (5 points) : &b I A K (:‘O I, ‘
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(b) Find the planar Earth “numerical distance” Wagon at a distance of 50 km. (10 points)
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J 3 an“ m5 in \ “2‘ (c) Find the groundwave electric ﬁeld amplitude received y a ve 'cal antenna on the ground at
distance 50 km. Use any ﬁgures or approximations ﬁ‘om the notes as necessary. Note for the spec iﬁed transmit antenna, 2Eo = 300.5 millivolts for distances speciﬁed in km. (15 points) “N
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 Spring '08
 Johnson,J

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