Antennas: Assignment 5:

1. Which one of the following substrates should be used to provide large gain and BW of MSA for same substrate thickness?

 RT Duroid 6010 (ε_r = 10.2, tan δ= 0.0023)

 Glass Epoxy FR-4 (ε_r = 4.4, tan δ = 0.02)

 RT Duroid 5880 (ε_r = 2.2, tan δ = 0.0009)

 Air (ε_r = 1, tan δ = 0)

Ans: d

Common data for Questions 2 to 6: A rectangular microstrip antenna (RMSA) is designed at 1800 MHz on a substrate having ε_r = 2.33, h = 1.6 mm and tan δ = 0.0012. 

2. Width of the RMSA is:

 8.33 cm

 6.46 cm

 4.17 cm

 3.34 cm

Ans: b

3. The effective dielectric constant seen by the  RMSA is: 

 3.15

 2.33

 2.26

 2.0

Ans: c

4. Length of the RMSA is:

 6.46 cm

 6.05 cm

 5.33 cm

 5.14 cm

Ans: c

5. For 50Ω input impedance, approximate location of the feed-point from the centre of RMSA is:

 0.5 cm

 1.0 cm

 1.5 cm

 2.0 cm

Ans: b

6. Approximate gain of the RMSA should be in the range:

 3-5 dBi

 5-7 dBi

 7-9 dBi

 9-11 dBi

Ans: d

7. To realize n-way power divider, circular microstrip patch should be excited in ___mode.

 TM₁₁

 TM₂₁

 TM₀₁

 TM₀₂

Ans: d

Common data for Questions 8 to 10: An air suspended circular microstrip antenna is designed to resonate at 2.45 GHz as shown in Fig.1. The suspended substrate parameters are: ε_r = 4.4, h = 0.16 cm and tan δ = 0.02, and the air-gap Δ = 0.6

8. The equivalent dielectric constant seen by the antenna is:

 2.83

 2.24

 1.86

 1.19

Ans: d

9. Approximate radius of the suspended circular MSA is:

 3.86 cm

 2.86 cm

 1.92 cm 

 1.16 cm

Ans: b

10. Approximate gain of the antenna is in the range:

 4-6 dBi

 6-8 dBi

 8-10 dBi

 10-12dBi

Ans: c