This document discusses microstrip patch antennas. It begins by explaining that microstrip antennas, also known as printed antennas, consist of a radiating metallic patch on a dielectric substrate with a ground plane on the other side. Microstrip antennas are widely used in mobile devices due to their conformal nature which allows them to be integrated into printed circuit boards. Their small size also helps minimize the overall size of mobile devices. The document then describes the basic structure and operating principles of microstrip patch antennas, noting that they function as resonant cavities and radiate strongly at resonant frequencies. It concludes by explaining that the bandwidth and size of microstrip antennas can be improved by defecting the ground plane and properly positioning the patch.

1. Presented by:
NAVEEN TOKAS
M.Tech – ECE
2nd Sem

2.  Antenna is a metallic device used for radiating
or receiving radio waves.
 Microstrip antenna is being extensively used in
mobile and other hand held communication
devices.
 The conformal nature of microstrip antenna
makes it an ideal choice for this type of devices.

3.  The microstrip antenna can be fabricated on the
same printed circuit board containing the
electronic components of the device. This leads
to effcient use of the available space and making
the device comapct.
 In the case of mobile or other small
communicating devices, the size of the antenna
plays a vital role. So, by reducing the size of the
antenna, the overall size of the device can be
reduced.

4.  In its most basic form, a Microstrip patch antenna consists of a
radiating patch on one side of a dielectric substrate which has a
ground plane on the other side.
 In general Micro strip antennas are also known as
“ PRINTED ANTENNAS ”.
 These are mostly used at microwave frequencies.
 Because the size of the antenna is directly tied the wavelength at the
resonant frequency.
 Micro strip patch antenna or patch antenna is a narrowband wide-beam
antenna.
Structure of a Microstrip Patch Antenna

5.  The patch acts approximately as a
resonant cavity (short circuit walls on top
and bottom, open-circuit walls on the
sides).
In a cavity, only certain modes are
allowed to exist, at different resonant
frequencies.
 If the antenna is excited at a resonant
frequency, a strong field is set up inside
the cavity, and a strong current on the
(bottom) surface of the patch. This
produces significant radiation (a good
antenna).

6.  Proper positioning of the patch above the
defected ground plane.
 Using dielectric substrate with high
permittivity.

7.  The size of the antenna can be reduced with
large enhancement in bandwidth by defecting
the ground plane and proper positioning of the
patch with respect to the defected ground
plane. With the proposed design, a maximum
size reduction of 75% in the antenna is possible
with dual broad bandwidth of about 3.02 GHz
(2.85-5.87GHz) and 1.4 GHz(7.10-8.5GHz)
which are 69% and 18% respectively around
their center frequencies.

8. Thank You