UNIT-1

1 The first antenna was built by [ ]

(a) J. D. Kraus (b) Guglielmo Marconi (c) Heinrich Hertz (d) R. J. Marhefka

2. The wavelength of 2-GHz wave is [ ]

(a) 15 cm (b) 15 mm (c) 1.5 cm (d) 1.5 mm

3. Identify the correct statement [ ]

(a) Time changing current radiates but accelerated charge does not radiate

(b) Time changing current does not radiate but accelerated charge radiates

(c) Both, time changing current and accelerated charge radiates

(d) Both time changing current and accelerated charge do not radiates

4. Gain of an antenna [ ]

(a)Varies inversly with square of wavelength

(b)Varies inversly with wavelength

(c)Varies Directly with square of wavelength

(d)Varies Directly with wavelength

5) From the circuit point of view an antenna appears to the transmission line as [ ]

(a) Input resistance (b) Radiation resistance

(c) Mutual impedance (d) Coupling impedance

6) If S(, ) is the Poynting vector and S(, ) max represents its maximum value the normalized power pattern is given by [ ]

(a) S(, ) / S(, )max (b) S(, )max / S(, ) (c) S(, )max - S(, ) (d) S(, )max + S(, )

7) The Poynting vector is given by S(, ) = [E2() + E2()] / Z0 where Z0 is [ ] (a) input impedance of the Tx- line (b) input impedance of the antenna

(c) intrinsic impedance of the space (d) combined impedance of Tx-line and antenna

8) If the (total) beam area A (or beam solid angle) consists of the main beam area M plus the minor-lobe area m (i.e. A = M + m) beam efficiency is given by [ ] (a) A / M (b) M / A (c) A / m (d) m / A

9) The directivity in terms of beam area A can be written as [ ] (a) A / 4 (b) 4 / A (c) A / 2 (d) 2 / A

10) If G is the gain k is the efficiency factor and D is the directivity of an antenna these are

related by [ ]

(a) G = k2 D (b) G = D / k

2 (c) G = D / k (d) G = k D

11) The directivity D is given in terms of the antenna aperture Ae by the following relation [ ]

(a) D = 4 Ae/2 (b) D = 4 2/Ae (c) D = Ae/4 2 (d) D = Ae/4

12) The field around an antenna may be divided into two principal regions called the near field or Fresnel

zone and far field or Fraunhofer zone. The boundary between the two regions may be arbitrarily

taken at a radius R for an antenna of maximum dimension L, where R and L are related by [ ]

(a) R = 2L2/2 (b) R = 2L/ 2 (c) R = 2L2/ (d) R = 2L/

13) Transmitting and Receiving antennas behave [ ]

(a) Identically (b) Differently (c) Cannot Determine (d) None of these

14) The voltage and current along antenna are [ ]

(a) Fixed at some value b) vary from one point to next

(c) Equal to unity d) Equal

15) The power gain and directivity are same except the power gain takes into account [ ]

a) Antenna losses b) Radiation resistance c) Antenna aperture d) Antenna area

16) Which of the minor lobe that ocupies the hemisphere opposite to the major lobe?

17) The lobe containing the direction of maximum radiation is called as_______.

18) The standard referance Antenna for Directive gain is______.

19) Aperture efficiency of an antenna is defined as______.

20) The reciprocity theorem for an antenna states that______.

21) In the radiation pattern electric field is a function of______.

22) FNBW is defined as______.

23) HPBW is defined as______.

24) Stray factor is defined as______.

25) Friis Transmision equation is ______.

Answers:

1)c 2)c 3)c 4)a 5)b 6)a 7)c 8)b 9)b 10)d

11)a 12)c 13)a 14)b 15)a 16) Back Lobe 17)Major Lobe

18) Isotropic Antenna 19) The ratio of Effective aperture to Physical aperture of antenna

20) **statement** 21) (Elevation angle)& (Azimuthal Angle)

22) Beam angle between two first Nulls 23) Beam angle between two Half power points

24) Ratio of minor lobe area to total Beam Area 25) Pr /Pt = Aer.Aet/r22