27-07-2012, 11:43 AM
MICROSTRIP PATCH ANTENNA AND PSO ALGORITHM
[attachment=29192]
INTRODUCTION
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 as shown in Figure 1. The patch is generally made of conducting material such as copper or gold and can take any possible shape. In order to simplify analysis and performance prediction, the patch is generally square, rectangular, circular, triangular, elliptical or some other common shape as shown in Figure 2. The radiating patch and the feed lines are usually photo etched on the dielectric
substrate.
PSO TECHNIQUE
PSO is a robust stochastic evolutionary computation technique based on the principle of movement of swarms. This technique has been applied for electromagnetic optimization recently. A swarm of bees flying in a field always try to find the location with the highest density of flowers. A bee starts from a random location & a random velocity. At each step the bee changes its velocity & position. Each position is represented by an N-dimensional co-ordinate, where each dimension corresponds to a parameter to be optimized. The velocity and position of a particle can be determined from the following equations:
ADVANTAGES AND DISADVANTAGES
Microstrip patch antennas are increasing in popularity for use in wireless applications due to their low-profile structure. Therefore they are extremely compatible for embedded antennas in handheld wireless devices such as cellular phones, pagers etc... The telemetry and communication antennas on missiles need to be thin and conformal and are often Microstrip patch antennas. Another area where they have been used successfully is in Satellite communication. Some of their principal advantages are given below:
FEED TECHNIQUES
Microstrip patch antennas can be fed by a variety of methods. These methods can be classified into two categories- contacting and non-contacting. In the contacting method, the RF power is fed directly to the radiating patch using a connecting element such as a microstrip line. In the non-contacting scheme, electromagnetic field coupling is done to transfer power between the microstrip line and the radiating patch. The four most popular feed techniques used are the microstrip line, coaxial probe (both contacting schemes), aperture coupling and proximity coupling (both non-contacting schemes).
Proximity Coupled Feed
This type of feed technique is also called as the electromagnetic coupling scheme. As shown in Figure 6, two dielectric substrates are used such that the feed line is between the two substrates and the radiating patch is on top of the upper substrate. The main advantage of this feed technique is that it eliminates spurious feed radiation and provides very high bandwidth (as high as 13%) , due to overall increase in the thickness of the microstrip patch antenna. This scheme also provides choices between two different dielectric media, one for the patch and one for the feed line to optimize the individual performances.
[attachment=29192]
INTRODUCTION
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 as shown in Figure 1. The patch is generally made of conducting material such as copper or gold and can take any possible shape. In order to simplify analysis and performance prediction, the patch is generally square, rectangular, circular, triangular, elliptical or some other common shape as shown in Figure 2. The radiating patch and the feed lines are usually photo etched on the dielectric
substrate.
PSO TECHNIQUE
PSO is a robust stochastic evolutionary computation technique based on the principle of movement of swarms. This technique has been applied for electromagnetic optimization recently. A swarm of bees flying in a field always try to find the location with the highest density of flowers. A bee starts from a random location & a random velocity. At each step the bee changes its velocity & position. Each position is represented by an N-dimensional co-ordinate, where each dimension corresponds to a parameter to be optimized. The velocity and position of a particle can be determined from the following equations:
ADVANTAGES AND DISADVANTAGES
Microstrip patch antennas are increasing in popularity for use in wireless applications due to their low-profile structure. Therefore they are extremely compatible for embedded antennas in handheld wireless devices such as cellular phones, pagers etc... The telemetry and communication antennas on missiles need to be thin and conformal and are often Microstrip patch antennas. Another area where they have been used successfully is in Satellite communication. Some of their principal advantages are given below:
FEED TECHNIQUES
Microstrip patch antennas can be fed by a variety of methods. These methods can be classified into two categories- contacting and non-contacting. In the contacting method, the RF power is fed directly to the radiating patch using a connecting element such as a microstrip line. In the non-contacting scheme, electromagnetic field coupling is done to transfer power between the microstrip line and the radiating patch. The four most popular feed techniques used are the microstrip line, coaxial probe (both contacting schemes), aperture coupling and proximity coupling (both non-contacting schemes).
Proximity Coupled Feed
This type of feed technique is also called as the electromagnetic coupling scheme. As shown in Figure 6, two dielectric substrates are used such that the feed line is between the two substrates and the radiating patch is on top of the upper substrate. The main advantage of this feed technique is that it eliminates spurious feed radiation and provides very high bandwidth (as high as 13%) , due to overall increase in the thickness of the microstrip patch antenna. This scheme also provides choices between two different dielectric media, one for the patch and one for the feed line to optimize the individual performances.