3.1 0th Iteration
The 0th iteration mainly consists of the basic patch with dimensions 11.33×11.33mm. The feed position is taken at 1.9mm from the x-axisas shown in the g.3.1 The R.L vs. frequency graph is shown in g.3.2. The g.3.3 shown below represents VSWR graph. The Smith Chart for change in Width is as shown in g.3.4.
Figure 3.1: 0th Iteration
Figure 3.2: R.L Vs Frequency Graph
Figure 3.3: VSWR Graph
Figure 3.4: Smith Chart
3.2 1st Iteration
The 1th iteration includes removing the slots having centre at 4.265mm from the axis and slot width of 2.6mm to increase the bandwidth of the antenna. In rst Iteration,the feed is given at a distance of 1.65mm from the centre.This is because the feed should be such that, the smith chart should passes from the centre, so that the impedance is 50 which is matched with probe feed connector leading to high power transfer.VSWR graph gives information about the frequency resonance and bandwidth. The R.L vs frequency graph is shown in g.3.6. The g.3.7 shown below represents VSWR graph. The Smith Chart for change in Width is as shown in g 3.8.
Figure 3.5: 1st Iteration
Figure 3.6: R.L Vs Frequency Graph
Figure 3.7: VSWR Graph
Figure 3.8: Smith Chart
The proposed antenna is designed by using concept of Minkowski fractal structure, which originates from the plane square patch and subsequent fractal antenna. Minkowski iterations produce a cross-like fractal patch with even more ne details at the edges. The antenna is designed by using the square patch and iterating rst iteration at the center of each side. Iterated polygons (indentation) in the shape of square are created. The square patch fractal antenna is based on minkowski square shape with a ground dimension of 38mX38mm and patch dimension of 11.33mmX11.33mm . The FR-4 material is used as substrate. The thickness of the substrate is 1.59 mm. The dielectric constant (r) of the antenna is 4.4.To design the fractal antenna a square shape structure is designed on the simulator.Square indentation is cut down from the each side of the square, by doing this the path for the current ow also increases and the e ciency of the antenna also increases.
Figure 4.1: R.L Vs Frequency Graph
Figure 4.2: VSWR
Figure 4.3: Smith Chart
Figure 4.4: Gain Vs Frequency
Figure 4.5: Radiation Pattern
A simple Square Microstrip patch antenna using air and FR4 dielectric is designed and optimised to operate over 4.5 GHz to 5.875 GHz. The parametric study, such as e ect of change in slot Width, Feed position on antenna radiation pattern is carried out to optimize the antenna structure.
A new technique of implementing Fractal Antenna can be evolved from this project. Plan of action for this semester was to complete the 0th and 1st iteration of simple Microstrip Patch which we have carried out successfully.
It is found that this structure with an indentation in the border length o ers considerable miniaturisation compared with a conventional square patch antenna. For this iteration the resonance frequencies decrease to lower side which indicates size reduction as compare to non fractal structure.
Our plan of action for next semester would be simulating the 2nd iteration and optimizing it to achieve maximum gain. The fabrication of the optimized antenna will be carried out followed by testing of the antenna.