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Question 202-1 : The advantage of the use of slotted antennas in modern radar technology is to ? [ Exam pilot ]

Virtually eliminate lateral lobes and as a consequence concentrate more energy in the main beam.

.the main advantage of a slotted antenna is that it produces a much narrower beam and eliminates most of the lateral lobes. therefore, more energy can be concentrated in the main beam or you can use less power to transmit. exemple 302 Virtually eliminate lateral lobes and as a consequence concentrate more energy in the main beam.

Question 202-2 : The frequency which corresponds to a wavelength of 12 cm is ?

2500 mhz.

.frequency mhz = 300 / wavelength m..frequency mhz = 300 / 0.12 m = 2500 mhz. exemple 306 2500 mhz.

Question 202-3 : A cumulonimbus cloud in the vicinity of an aeroplane can cause certain navigation systems to give false indications. this is particularly true of the ?

Adf.

exemple 310 Adf.

Question 202-4 : A radio altimeter employing a continuous wave signal would have ?

A directional aerial for transmission and another one for reception.

.a radio altimeter is a self contained on board aid which indicates the true height or the lowest wheels with regard to the ground..a continuous wave fm radio beam in the shf band 4200 4400 mhz is directed towards the ground in a 30° cone fore and aft, and 30° athwartships across the ship from side to side. the signal is reflected back to the aircraft..continuous wave as opposed to pulse radar eliminates minimum target reception range, since the time delay for a pulsed signal would be too small to measure properly as well, the antennae cannot switch between transmit and receive that quickly. as the potential time interval is very small, you need separate transmitter and receiver aerial. exemple 314 A directional aerial for transmission and another one for reception.

Question 202-5 : Which statement relating to the stabilization of airborne weather radar antennae is true ?

They are stabilized with respect to the pitch and rollaxis but not with respect to the yaw axis.

exemple 318 They are stabilized with respect to the pitch and rollaxis but not with respect to the yaw-axis.

Question 202-6 : The antennae of modern airborne weather radars are stabilized by means of ?

Inputs from the aircraft's attitude system.

.automatic antenna stabilization, as employed in today's weather avoidance radar systems, consists of an electro mechanical means of maintaining a selected beam scan relative to the earth's horizon during moderate aircraft maneuvers. to accomplish this, a reference is established by the aircraft's vertical gyro, usually a component of the autopilot or integrated flight control system. exemple 322 Inputs from the aircraft's attitude system.

Question 202-7 : The type of modulation used for the ils frequency carrier is ?

Amplitude modulation.

.amplitude modulation the information that is impressed onto the carrier wave by altering the amplitude of the carrier. exemple 326 Amplitude modulation.

Question 202-8 : The quadrantal error of an adf ?

Is caused by the refraction from the aircraft's fuselage and is compensated for.

.the quadrantal error is a distortion of the incoming signal from the ndb station by re radiation from the airframe. this is corrected for during installation of the antenna. exemple 330 Is caused by the refraction from the aircraft's fuselage and is compensated for.

Question 202-9 : The skip distance of hf transmission will increase with ?

Higher frequency and higher position of the reflecting ionospheric layer.

.skip distance the distance between the transmitter and the point on the surface of the earth where the first sky return arrives...it will increase for a higher frequency..it will increase for a higher position of the reflecting ionospheric layer. exemple 334 Higher frequency and higher position of the reflecting ionospheric layer.

Question 202-10 : Which statement about the errors and effects on ndb radio signals is correct ?

The mountain effect is caused by reflections onto steep slopes of mountainous terrain which may cause big errors in the bearing.

.mountain effect mountain areas can cause reflections and, to a lesser extent, diffractions and lead to the error direction reading by adf..this effect, similar to night effect, is obtained in mountainous areas where the energy received from an ndb consists of two or more waves, one of them direct and others by reflection from the mountains. bearing indications are found to change rapidly until the affected area is passed...for information, night effect radio waves take two paths to the radio compass receiver. the first and normal path is along the earth's surface. if only these waves were received, the compass would point directly to the ndb. the second path is via one or more wave refracting layers above the earth the ionosphere returning to earth to mix with direct waves. complete changes in the nature of the waves take place on this path and produce errors in direction. exemple 338 The mountain effect is caused by reflections onto steep slopes of mountainous terrain which may cause big errors in the bearing.

Question 202-11 : What causes the so called night effect ?

A change in the direction of the plane of polarisation due to reflection in the ionosphere.

. night effect is the influence of sky waves and ground waves arriving at the adf receiver lead at a difference of phase and polarisation which introduce bearing errors at night...night effect predominates around dusk and dawn. exemple 342 A change in the direction of the plane of polarisation due to reflection in the ionosphere.

Question 202-12 : An amplitude modulation is shown in the figure. 2069 ?

A.

exemple 346 A.

Question 202-13 : In his basic type, a dipole antenna adapted for a frequency of 110 mhz, will have a wire of length of ?

136 cm.

.wavelength in meter = 300 / frequency in mhz.wavelength in meter = 300 / 110 = 2.72 m 272 cm..a dipole antenna is a wire of length equal to one half of the wavelength..272 cm / 2 = 136 cm. exemple 350 136 cm.

Question 202-14 : How is the unit hertz hz defined ?

The number of electromagnetic oscillations per second.

.frequency is the number of cycles occurring in one second in a radio wave expressed in hertz hz. frequency is normally given in hertz hz where 1 hz = 1 cycle/second..a cycle is defined as a complete series of values of a periodical process. 2549 exemple 354 The number of electromagnetic oscillations per second.

Question 202-15 : An ndb transmits on 427 khz. the corresponding wavelength is ?

702,5 m.

.frequency khz = speed of light / wavelength m..427 khz = 300000 / wavelength m..wavelength m = 300000 / 427 = 702.57 m. exemple 358 702,5 m.

Question 202-16 : An electromagnetic wave consists of an oscillating electric field e and an oscillating magnetic field h. their propagation speed is ?

The speed of light.

.propagation speed is the speed at which radio wave radiates through space..depending upon the electrical nature of the medium through which it travels, the speed varies slightly. we can assume a constant speed of light value of 300,000,000 meters 162,000 nm per second. exemple 362 The speed of light.

Question 202-17 : The electromagnetic waves refracted from the e and f layers of the ionosphere are called ?

Sky waves.

exemple 366 Sky waves.

Question 202-18 : The simplest type of antenna construction is a ?

Dipole antenna which is a wire of length equal to one half of the wavelength.

. 2550. dipole antenna. exemple 370 Dipole antenna which is a wire of length equal to one half of the wavelength.

Question 202-19 : An electromagnetic wave consists of an oscillating electric field e and an oscillating magnetic field h. which statement is correct ?

The e and h fields are perpendicular to each other.

exemple 374 The (e) and (h) fields are perpendicular to each other.

Question 202-20 : The frequency which corresponds to a wavelength of 8.25 m is ?

36.36 mhz

.frequency mhz = 300 / wavelength m..frequency = 300 / 8.25 m..frequency = 36.36 mhz. exemple 378 36.36 mhz

Question 202-21 : The frequency which corresponds to a wavelength of 3 km is ?

100 khz.

.frequency f in khz = 300000 / wavelength m.frequency f in khz = 300000 / 3000 m.frequency f in khz = 100 khz. exemple 382 100 khz.

Question 202-22 : Wavelength of frequency 117.95 mhz is ?

2.5 m.

.wavelength m = 300000 / frequency khz..wavelength m = 300 / frequency mhz..wavelength m = 300 / 117.95 = 2.54 m. exemple 386 2.5 m.

Question 202-23 : Concerning the wave propagation in the ionosphere, we denote three layers. those three layers are ?

D, e and f layers and their depth varies with time.

. 2551.the ionosphere is the ionized component of the earth's upper atmosphere from 60 to 400 km above the surface, which is vertically structured in three regions or layers d, e and f. exemple 390 D, e and f layers and their depth varies with time.

Question 202-24 : Radio waves travel at ?

The speed of light.

exemple 394 The speed of light.

Question 202-25 : In accordance with the itu international telecommunication union a radio signal may be classified by three symbols. third symbol indicates. e.g. a1a ?

Nature of information to be transmitted.

.radio signal may be classified by three symbols in accordance with the itu. first symbol indicates the type of modulation of the main carrier.. second symbol indicates the nature of the signal modulating the main carrier.. third symbol indicates the nature of the information to be transmitted...for information only. you do not have to know that for the exam.a1a telegraphy on off keying without modulation by an audio frequency..a double sideband.1 single channel containing quantized or digital information without the use of a modulating sub carrier.a telegraphy for aural reception. exemple 398 Nature of information to be transmitted.

Question 202-26 : In accordance with the itu international telecommunication union a radio signal may be classified by three symbols. second symbol indicates. e.g. a1a ?

Nature of signal s modulating the main carrier.

.a radio signal may be classified by three symbols in accordance with the itu radio regulation volume 1 e.g. a1a. first symbol indicates the type of modulation of the main carrier.. second symbol indicates the nature of the signal modulating the main carrier.. third symbol indicates the nature of the information to be transmitted. exemple 402 Nature of signal(s) modulating the main carrier.

Question 202-27 : In accordance with the itu international telecommunication union a radio signal may be classified by three symbols. first symbol indicates.. e.g. a1a ?

Type of modulation of the main carrier.

.radio signal may be classified by three symbols in accordance with the itu. first symbol indicates the type of modulation of the main carrier.. second symbol indicates the nature of the signal modulating the main carrier.. third symbol indicates the nature of the information to be transmitted...for information only. you do not have to know that for the exam.a1a telegraphy on off keying without modulation by an audio frequency..a double sideband.1 single channel containing quantized or digital information without the use of a modulating sub carrier.a telegraphy for aural reception. exemple 406 Type of modulation of the main carrier.

Question 202-28 : Vhf very high frequency waves appear in the frequency spectrum ?

30 mhz 300 mhz

. 1682 exemple 410 30 mhz - 300 mhz

Question 202-29 : With regard to radio waves propagation, a cycle is defined as ?

A complete series of values of a periodical process.

.this is the official easa definition. a cycle is any complete round or series of occurrences that repeats or is repeated.. 2549 exemple 414 A complete series of values of a periodical process.

Question 202-30 : Vlf very low frequency waves appear in the frequency spectrum ?

3 khz 30 khz

. 1682 exemple 418 3 khz - 30 khz

Question 202-31 : Lf low frequency waves appear in the frequency spectrum ?

30 khz 300 khz

. 1682 exemple 422 30 khz - 300 khz

Question 202-32 : Mf medium frequency waves appear in the frequency spectrum ?

300 khz 3000 khz

. 1682 exemple 426 300 khz - 3000 khz

Question 202-33 : Hf high frequency waves appear in the frequency spectrum ?

3 mhz 30 mhz

. 1682 exemple 430 3 mhz - 30 mhz

Question 202-34 : Uhf ultra high frequency waves appear in the frequency spectrum ?

300 mhz 3000 mhz

. 1682 exemple 434 300 mhz - 3000 mhz

Question 202-35 : Shf super high frequency waves appear in the frequency spectrum ?

3 ghz 30 ghz

. 1682 exemple 438 3 ghz - 30 ghz

Question 202-36 : Ehf extremely high frequency waves appear in the frequency spectrum ?

30 ghz 300 ghz

. 1682 exemple 442 30 ghz - 300 ghz

Question 202-37 : Frequency is defined as the ?

Number of cycles occurring in one second in a radio wave expressed in hertz hz.

.a cycle is any complete round or series of occurrences that repeats or is repeated.. 2549.the frequency is the number of cycles occurring in one second in a radio wave expressed in hertz hz. exemple 446 Number of cycles occurring in one second in a radio wave expressed in hertz (hz).

Question 202-38 : Which statement about vhf/uhf frequencies is correct ?

For both vhf/uhf propagation, the space wave is the only propagation path of practical use. there is no sky wave under normal conditions.

.radio waves in vhf, uhf, shf and ehf propagate as space waves..radio waves in vlf, lf, mf and hf propagate as surface/ground waves and sky waves. exemple 450 For both vhf/uhf propagation, the space wave is the only propagation path of practical use. there is no sky wave under normal conditions.

Question 202-39 : Diffraction is the process by which ?

Radio wave travel over and around obstacles.

.diffraction is the phenomenon by which wave energy bends around an object. exemple 454 Radio wave travel over and around obstacles.

Question 202-40 : Antennas...an ac will be induced ?

In a wire, parallel to a wire fed with an ac, but remote from it.

.inductive coupling refers to the phenomenon that exists when a magnetic field created by an electrical current induces an effect on something else. when this happens, the two then become mutually reactive, or coupled, by the inductive effects of the magnetic field. for example, when an electrical current passes through a wire, the electromagnetic field created can induce an electrical current in another wire, causing the two to be inductively coupled. the principles and effects of inductive coupling find use in devices such as transformers and electric motors...the effects of inductive coupling can be used in one of three primary ways. first, the inducing field can create a specifically desired electrical current, such as in transformers. second, the inducing field can create a specifically desired mechanical effect, such as in electric motors. finally, the inducing field can create a resonance, which itself can create specifically desired electrical currents, such as in radio transmission and reception and non contact charging devices...in transformers, an electrical current conducts through a wire wound around a core of some type, called the primary winding. this wire is intentionally placed near another wire wound around the same core, called the secondary winding..the electromagnetic field, created by passing current through the primary winding, then induces an electrical current in the secondary winding...resonant devices work in a way similar to transformers, though, without the paired windings. in these devices, a standing electromagnetic field is created. when this field encounters an antenna, the effect of inductive coupling causes the antenna to resonate, which, in turn, induces an electrical current at its feed point. in the case of a radio, the induced current is amplified and heard over the radio. in a charging device, the induced current is directly applied to a battery's terminals to recharge it. exemple 458 In a wire, parallel to a wire fed with an ac, but remote from it.


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