Master Thesis

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3.1 Introduction Chapter 3 X Antenna Many wireless application systems use microstrip patch antennas due to their compact, conformal, and low-‐cost designs. The X Antenna is also designed on the basics of microstrip technology. We call it X Antenna because there are two diagonal slots in the patch which makes an X shape in the patch. The slots are used to achieve circular polarization. Circularly polarized antennas are particularly of interest to radio communication. Enabling the space orientation, such antennas also reduce considerably the multipath fading and thus increase the spectral efficiency of RF systems. In addition, the use of receive and transmit antennas with circular polarization can maximize the isolation between the two antennas [3]. 3.2 Design Figure 3.1 shows the top and side view of the optimized single-‐feed patch antenna operating at 5.8 GHz and having a circular polarization. This antenna is designed using both Microwave Office and HFSS-‐Ansoft software. (a) (b) Figure 3.1 Top (a) and Side (b) view of X Antenna Firstly it was required to determine the resonant length of the antenna, which in circular antenna can be called the diameter. So the diameter of the patch for a frequency of 5.8 GHz and dielectric of 4.3 was calculated as ð� L =12.2 mm 20
However when the design was optimized the diameter was found to be 11.6 mm. So the antenna is composed of a circular patch with a radius of 5.8 mm printed on a FR4 substrate with εr =4.3 and thickness of 3.2mm. The two diagonal slots have length of 9mm and width of 0.5mm. The antenna is fed by a probe with a radius of 1.3 mm. The feed location and the slots were optimized to give good impedance matching and circular polarization. The size of the ground plane is 21 mm 21 mm. The hole in the ground plane for the SMA connection is 4 mm. 3.3 Results The results are obtained from both HFSS and Microwave Office and are quite similar. In the following chapter the simulated results on both tools are presented. 3.3.1 Simulated Results Return Loss The simulated return loss of the optimized antenna from MWO is shown in figure 3.2. At 5.8 GHz a return loss of -‐11 dB is achieved. Figure 3.2 Return Loss of X Antenna in Microwave Office In comparison to MWO the return loss in HFSS showed slightly better matching. The figure 3.3 shows the return loss from HFSS. At 5.8 GHz a return loss of -‐14 dB is achieved. 21
Page 1 and 2: Master Thesis Design of Microstrip
Page 3 and 4: Chapter 4 3.1 Introduction………
Page 5 and 6: Acknowledgement I would like to exp
Page 7 and 8: 1.1 Kapsch TrafficCom Chapter 1 Ove
Page 9 and 10: The On-‐Board Units above provi
Page 11 and 12: 2.1 Introduction Chapter 2 Introduc
Page 13 and 14: Since this notation frequently caus
Page 15 and 16: 2.5 Antenna Parameters Figure 2.5 A
Page 17 and 18: 2.5.3 Return Loss Return loss is an
Page 19: 2.5.7 Conversion Gain The conversio
Page 23 and 24: It can be seen that radiation patte
Page 25 and 26: Similarly, the axial ratio from HFS
Page 27 and 28: Cross Polarization The cross polari
Page 29 and 30: Figure 4.1 (b) Side view of the ant
Page 31 and 32: Gain Figure 4.5 Radiation Pattern f
Page 33 and 34: Similarly axial ratio from HFSS is
Page 35 and 36: Cross polarization Cross polarizati
Page 37 and 38: 5.1 Introduction Chapter 5 Patch An
Page 39 and 40: Similarly return loss in HFSS is sh
Page 41 and 42: Axial Ratio Figure 5.7 Gain (RHCP a
Page 43 and 44: 5.3.2 Measured Results Different me
Page 45 and 46: 6.1 Introduction Chapter 6 Truncate
Page 47 and 48: Cross polarization (a) (b) Figure 6
Page 49 and 50: esults and was centered at 5.8 GHz
Page 51 and 52: Return Loss The return loss for thi
Page 53 and 54: Axial Ratio Axial ratio gives an id
Page 55 and 56: 6.3.5 Simulated Results for Antenna
Page 57 and 58: Axial Ratio Axial ratio is another
Page 59 and 60: The results are very identical to t
Page 61 and 62: Results The simulation results of t
Page 63 and 64: 7.3 Spiral Antenna A spiral antenna
Page 65 and 66: Axial Ratio The axial ratio plot is
Page 67 and 68: 7.5 Conclusion All three antennas d
Page 69 and 70: 0 -‐2 -‐4 -‐6 -‐8 -
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Similarly the return loss measured
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Chapter 9 Conclusion Different Ante
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X Antenna (with 1.6 mm Substrate) A
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References [1] Per-‐Simon Kilda
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Master Thesis

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