Antennas: Assignment 2

1. The power transmitted by a broadband FM tower antenna is:

 100 – 1000 KW

 10 – 100 KW

 1 – 10 KW

 100 W – 1 KW

Ans: c

2. The body temperature of a person is around 37oCelsius. After use of cell phone for approx. 20 – 30 minutes continuously on side of one ear, the approximate temperature of the ear lobe will be:

40oC

39oC

38oC

37oC

Ans: c

3. People living within _____ meter in the main beam of cell tower antenna are considered to be in extremely high radiation zone.

 50

 100

 200

 300

Ans: a

4. Common Data for Questions 4-6: 

A printed dipole antenna is designed at 900 MHz on FR4 substrate having e_r = 4.4, h = 1.6 mm and tand = 0.02. The width of the dipole is 5 mm.

The approximate resonant length of the dipole is:

 184 mm

 148 mm

 92 mm

 74 mm

Ans: b

5. Approximate gain of the antenna is:

 5.0 dBi

 4.0 dBi

 2.0 dBi

 1.0 dBi

Ans: c

6. The radiation pattern of the dipole antenna is:

  

       

       

   

       

Ans: a

7. The input resistance Rin of a 2-fold half wavelength dipole antenna is approximately:

 68 Ω

 136 Ω

 272 Ω 

 1088 Ω

Ans: c

8. The length and diameter of a dipole antenna are 28 cm and 8 mm, respectively. Its approximate resonance frequency is:

 250 MHz

 500 MHz

 750 MHz

 1 GHz

Ans: b

9. A λ/2 dipole antenna is designed at 2.45 GHz. If a metallic plate is placed behind the antenna at a distance of λ/4, then: 

 Frequency doubles

 Bandwidth doubles

 Gain doubles 

 All of the above 

Ans: c

10. Bandwidth of a dipole antenna can be increased by:

 Increasing the diameter of the dipole

 Using printed bow-tie configuration

 Using bi-conical configuration 

 All of the above

Ans: d