Antennas: Assignment 6:

1. For conventional microstrip antenna design, if height of the substrate increases, its

(i)  Bandwidth increases                    (ii) Losses increases

(iii) Efficiency decreases                     (iv) Gain decreases

 (i)

 (i) and (ii)

 (i) and (iii)

 (i), (ii) and (iii)

Ans: c

2. For same substrate specifications, two gap coupled semi-circular MSAs provide ________ in comparison with conventional circular MSA.

(i) Broader bandwidth,                                  (ii) Uniform gain

(iii) Lesser bandwidth                                    (iv) Non-uniform gain

 (i) and (ii)

 (i) and (iv)

 (ii) and (iii)

 (iii) and (iv)

Ans: b

3. Rectangular microstrip antenna with U-slot does not provide: 

 Asymmetric radiation pattern

 Broad bandwidth

 Less size

 Uniform gain

Ans: d

4. Electromagnetically coupled two metallic circular patches are stacked on each other in air with support of metallic post at the centre. The parasitic patch should have:

 Larger radius than the fed patch

 Smaller radius than the fed patch

 Same radius as the fed patch

 Either smaller or same radius as the fed patch

Ans: b

5. Which one of the following configurations of microstrip antenna has least bandwidth?

 Air suspended

 Gap coupled

 Directly coupled

 Electromagnetically coupled

Ans: a

6. Common Data for Questions 6 to 9: An air suspended rectangular MSA is designed at a height of 2 mm with its patch length and width of 57 mm and 61 mm, respectively. Antenna resonates at 2.45 GHz but it provides less bandwidth. To increase the bandwidth, following options are possible:

The height of the bottom patch is increased to 6 mm. For same patch width and frequency of operation,  modified patch length should be:

 65 mm

 61 mm

 57 mm

 50 mm

Ans: d

 7. A rectangular metallic patch stacked vertically at gap of 5 mm from the bottom patch (as mentioned in Question 6) to get it electromagnetically coupled. For same patch width i.e.  61mm, approximate length of the top patch should be:

 46 mm 

 52 mm

 57 mm

 61 mm

Ans: a

8. What will be the approximate peak gain for the configuration in Question 7?

 10-12 dBi

 8-10 dBi

 6-8 dBi

 < 6 dBi

Ans: b

9. Two identical rectangular patches are gap coupled at 2 mm gap on left and right sides of the fed patch (length = 57 mm, width = 61 mm). These gap coupled patches are mounted using metallic shorting post at their centres. What should be the approx. length of the parasitic patches for 61 mm width? 

 60 mm

 57 mm

 54 mm

 50 mm

Ans: c

10. The stacked planar microstrip antenna configurations (1B3T or 1B4T) provide

(i)  Broad bandwidth                                                 (ii)  Uniform gain

(iii) Stable broadside radiation pattern                   (iv) Unstable radiation pattern

 (i) and (ii)

 (i), (ii) and (iii)

 (i), (ii) and (iv)

 (ii) and (iii)

Ans: b