Radio Wave Propagation

E3A01 (D)What is the maximum separation between two stations communicating by moonbounce?

D. Any distance as long as the stations have a mutual lunar window

E3A02 (B)What characterizes libration fading of an earth-moon-earth signal?

B. A fluttery irregular fading

E3A03 (A)When scheduling EME contacts, which of these conditions will generally result in the least path loss?

A. When the moon is at perigee

E3A04 (D)What type of receiving system is desirable for EME communications?

D. Equipment with very low noise figures

E3A05 (A)What transmit and receive time sequencing is normally used on 144 MHz when attempting an earth-moon-earth contact?

A. Two-minute sequences, where one station transmits for a full two minutes and then receives for the following two minutes

E3A06 (C) What transmit and receive time sequencing is normally used on 432 MHz when attempting an EME contact?

C. Two and one half minute sequences, where one station transmits for a full 2.5 minutes and then receives for the following 2.5 minutes

E3A07 (B)What frequency range would you normally tune to find EME stations in the 2-meter band?

B. 144.000 - 144.100 MHz

E3A08 (D)What frequency range would you normally tune to find EME stations in the 70-cm band?

D. 432.000 - 432.100 MHz

E3A09 (A)When a meteor strikes the earth's atmosphere, a cylindrical region of free electrons is formed at what layer of the ionosphere?

A. The E layer

E3A10 (C) Which range of frequencies is well suited for meteor-scatter communications?

C. 28 - 148 MHz

E3A11 (C) What transmit and receive time sequencing is normally used on 144 MHz when attempting a meteor-scatter contact?

C. 15-second sequences, where one station transmits for 15 seconds and then receives for the following 15 seconds

E3B01 (A)What is transequatorial propagation?

A. Propagation between two points at approximately the same distance north and south of the magnetic equator

E3B02 (C) What is the approximate maximum range for signals using transequatorial propagation?

C. 5000 miles

E3B03 (C) What is the best time of day for transequatorial propagation?

C. Afternoon or early evening

E3B04 (A)What type of propagation is probably occurring if an HF beam antenna must be pointed in a direction 180 degrees away from a station to receive the strongest signals?

A. Long-path

E3B05 (C) On what amateur bands can long-path propagation provide signal enhancement?

C. 160 to 10 meters

E3B06 (B)What amateur band consistently yields long-path enhancement using a modest antenna of relatively high gain?

B. 20 meters

E3B07 (D)What is the typical reason for hearing an echo on the received signal of a station in Europe while directing your HF antenna toward the station?

D. There are two signals being received, one from the most direct path and one from long-path propagation

E3B08 (D)What type of propagation is probably occurring if radio signals travel along the terminator between daylight and darkness?

D. Gray-line

E3B09 (A)At what time of day is gray-line propagation most prevalent?

A. Twilight, at sunrise and sunset

E3B10 (B)What is the cause of gray-line propagation?

B. At twilight solar absorption drops greatly while atmospheric ionization is not weakened enough to reduce the MUF

E3B11 (C) What communications are possible during gray-line propagation?

C. Contacts up to 8,000 to 10,000 miles on three or four HF bands

E3C01 (D)What effect does auroral activity have upon radio communications?

D. CW signals have a fluttery tone

E3C02 (C) What is the cause of auroral activity?

C. The emission of charged particles from the sun

E3C03 (D)Where in the ionosphere does auroral activity occur?

D. At E-region height

E3C04 (A)Which emission mode is best for auroral propagation?

A. CW

E3C05 (B)What causes selective fading?

B. Phase differences between radio-wave components of the same transmission, as experienced at the receiving station

E3C06 (A)How does the bandwidth of a transmitted signal affect selective fading?

A. It is more pronounced at wide bandwidths

E3C07 (A)How much farther does the VHF/UHF radio-path horizon distance exceed the geometric horizon?

A. By approximately 15% of the distance

E3C08 (B)For a 3-element beam antenna with horizontally mounted elements, how does the main lobe takeoff angle vary with height above flatground?

B. It decreases with increasing height

E3C09 (B)What is the name of the high-angle wave in HF propagation that travels for some distance within the F2 region?

B. Pedersen ray

E3C10 (C) What effect is usually responsible for propagating a VHF signal over 500 miles?

C. Tropospheric ducting

E3C11 (B)For a 3-element beam antenna with horizontally mounted elements, how does the main lobe takeoff angle vary with the downward slope of the ground (moving away from the antenna)?

B. It decreases as the slope gets steeper

E3C12 (B)In the northern hemisphere, in which direction should a directional antenna be pointed to take maximum advantage of auroral propagation?

B. North

E3C13 (B)As the frequency of a signal is increased, how does its ground wave propagation change?

B. It decreases

E3C14 (A)What typical polarization does ground-wave propagation have?

A. Vertical

E3C15 (D)Why does the radio-path horizon distance exceed the geometric horizon?

D. Radio waves may be bent