The document provides an overview of microstrip patch antennas, detailing their shapes, substrate materials, and feeding methods. It includes calculations for patch dimensions, effective lengths, and directivity formulas for rectangular patch antennas. Additionally, it suggests ways to improve performance issues such as low power, gain, and bandwidth constraints.

1. Microstrip Patch Antenna
Presented by,
A.Priyanka

2. Patch Antenna
TopView of Patch Antenna Side view of Patch Antenna

3. Different shapes of antenna

4. Substrate
• The most commonly used substrates are,
1) Honey comb(dielectric constant=1.07)
2)RT Duroid(dielectric constant=2.32)
3)Quartz(dielectric constant=3.8)
4)Alumina(dielectric constant=10)
dielectric constant:
2.2≤𝝐 𝒓≤12

5. Feeding methods
Coaxial probe feedMicrostrip line feed

6. Feeding methods
Proximity coaxial feedAperture coupled feed

7. Comparing different feed techniques

8. Rectangular Patch Antenna
• The length of the patch is:
𝜆0
3
< 𝐿 <
𝜆0
2
• At low frequencies, initial vales of 𝝐 𝒓eff. referred to as the static values and are
given by:
𝝐 𝒓eff. =
𝝐 𝒓
+1
2
+
𝝐 𝒓
−1
2
[1+
12ℎ
𝑤
]-1/2
Where,
h= height of substrate
w= width of the patch

9. Rectangular Patch Antenna
• For an efficient radiator, practical width that leads to good radiator
efficiencies is:
W =
1
2𝑓𝑟 𝜇0
𝜖0
2
𝜖 𝑟
+1
=
𝑣0
2𝑓𝑟
2
𝜖 𝑟
+1
• For normalized extension of length:
∆𝐿
ℎ
= 0.412
(𝝐 𝒓eff.+0.3)(
𝑊
ℎ
+0.264)
(𝝐 𝒓eff.−0.258)(
𝑊
ℎ
+0.8)
Where,v0= free space velocity of light

10. Rectangular Patch Antenna
• Directivity of the single patch is:
D0 = {5. 2dB W<<𝜆0
4(
𝑊
𝜆0
) W>>𝜆0
• Finally, the effective length of the patch is:
Leff. = L+2 ∆𝐿
Where, ∆𝐿= extended length of the patch

11. Rectangular Patch Antenna
• The actual length of the patch can be determined by solving:
L =
1
2𝑓𝑟 𝝐 𝒓eff. 𝜇0
𝜖0
- 2 ∆𝐿
• Finally, the effective length of the patch is:
Leff. = L+2 ∆𝐿
Where, ∆𝐿= extended length of the patch

12. Remedies:
• Low power and low gain can overcome by arrays
configuration.
•The band width can increase up to 60% by using some
special techniques.
•Surface wave associated limitations such as poor
efficiency,increased mutual coupling , reduced gain and
radiation pattern can overcome.

13. Thank you