2. ANALYSIS OF LOW PROFILE ANTENNAS
2.1 INTRODUCTION:
An antenna (or aerial) is an electrical device which converts electric power into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver. In transmission, a radio transmitter supplies an oscillating radio frequency electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce a tiny voltage at its terminals, that is applied to a receiver to be amplified.
2.2 TYPES OF ANTENNA:
Wire Antennas
• Dipole Antenna
• Half-Wave Dipole
• Monopole Antenna
• Folded Dipole Antenna
• Loop Antenna
Travelling Wave Antennas
• Helical Antennas
• Yagi - Uda Antennas
Log-Periodic Antennas
• Log-Periodic Antennas
• Log-Periodic Dipole Array
Microstrip Patch Antennas
• Rectangular Microstrip Antenna
• Elliptical Microstrip Patch Antenna
Reflector Antennas
• Parabolic Reflector (Dish Antenna)
Aperture Antennas
• Inverted-F Antenna
• Slotted Waveguide Antenna
• Horn Antenna
There are various types of antennas in RF Systems . Some of the antennas we are considering under certain concerns for body worn applications at 60 GHz. In body worn application, the antenna should be of smaller in size and should have high gain, high directivity, high return loss, low input impedance. So we analyzed Patch antenna, horn antenna, monopole and dipole antenna.
2.3 RESULTS OF THE VARIOUS LOW PROFILE ANTENNA AT 2.4 GHz:
Antenna
Types Min Return
Loss at (GHz) Range (GHz) Input
Impedance Gain
Patch Elip_Edge fed 2.3337 2.2010-2.4905 0.2896 6.93 dB
Patch Elip_insert fed 2.8161 2.5025-3.2020 0.2070 ...
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...6h+L=6(0.2)+1.559mm= 2.769mm
W g= 6h+W=6(0.2)+1.976mm= 3.176mm
Step 7: Determination of feed point location (X f ,Y f ):
A coaxial probe type feed is to be used in this design. The center of the patch is taken as the origin and the feed point location is given by the co-ordinates ( X f ,Y f ) from the origin. The feed point must be located at that point on the patch, where the input impedance is 50 ohms for the resonant frequency. Hence, a trial and error method is used to locate the feed point. For different locations of the feed point, the return loss (R.L) is compared and that feed point is selected where the R.L is most negative. We have choosen the feed point position value as,
(X f ,Y f )=(-0.3,-0.4)
As the feed point is mostly placed ( ) distance from the centre or
(3 /4) distance from the edges. So by trial and error condition, we fixed a point (X f ,Y f).
Radio systems must have transmitter to modulate some property of the energy produced to impress a signal on it. To using amplitude modulation or angle modulation ,which can be frequency modulation or phase modulation. Radio systems have antenna to convert
Set the stripping section difference point Δs. The point Δs is to be set at a point where
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