ANSWERS TO QUESTIONS Q1. THROUGH Q48.

A1. Induction field and radiation field.
A2. Induction field.
A3. Radiation field.
A4. Fundamental frequency.
A5. Harmonic frequency or harmonics.
A6. 30 meters.
A7. 5 megahertz.
A8. Vertically polarized.
A9. Direction of wave propagation.
A10. Shifting in the phase relationships of the wave.
A11. Troposphere, stratosphere, and ionosphere.
A12. Stratosphere.
A13. Whether the component of the wave is travelling along the surface or over the surface of the earth.
A14. Radio horizon is about 1/3 farther.
A15. Sea water.
A16. (a) electrical properties of the terrain(b) frequency(c) polarization of the antenna
A17. High energy ultraviolet lightwaves from the sun.
A18. D, E, F₁, and F₂ layers.
A19. D layer is 30-55 miles, E layer 55-90 miles, and F layers are 90-240 miles.
A20. Thickness of ionized layer.
A21. Critical frequency.
A22. (a) density of ionization of the layer(b) frequency(c) angle at which it enters the layer
A23. A zone of silence between the ground wave and sky wave where there is no reception.
A24. Where ionization density is greatest.
A25. A term used to describe the multiple pattern a radio wave may follow.
A26. Selective fading.
A27. Natural and man-made interference.

A28. Natural.
A29. Man-made.
A30. (a) filtering and shielding of the transmitter(b) limiting bandwidth(c) cutting the antenna to the correct frequency
A31. (a) physical separation of the antenna(b) limiting bandwidth of the antenna(c) use of directional antennas
A32. Regular and irregular variations.
A33. Regular variations can be predicted but irregular variations are unpredictable.
A34. Daily, seasonal, 11-year, and 27-days variation.
A35. Sporadic E, sudden disturbances, and ionospheric storms.
A36. Muf is maximum usable frequency. Luf is lowest usable frequency. Fot is commonly known as optimum working frequency.
A37. Muf is highest around noon. Ultraviolet lightwaves from the sun are most intense.
A38. When luf is too low it is absorbed and is too weak for reception.
A39. Signal-to-noise ratio is low and the probability of multipath propagation is greater.
A40. Frequent signal fading and dropouts.
A41. Fot is the most practical operating frequency that can be relied on to avoid problems of multipath, absorbtion, and noise.
A42. They can cause attenuation by scattering.
A43. It can cause attenuation by absorbtion.
A44. It is a condition where layers of warm air are formed above layers of cool air.
A45. It can cause vhf and uhf transmission to be propagated far beyond normal line-of-sight distances.
A46. Troposphere.
A47. Vhf and above.
A48. Near the mid-point between the transmitting and receiving antennas, just above the radio horizon.