Design of Antennas for Handheld DVB-H ... - Lunds tekniska högskola

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Figure 4.16. Loop antenna. Figure 4.17. Loop antenna return loss graph. The experience from designing loop antennas for DVB-H is that the shape of the antenna is flexible and does not affect the performance. The size of the loop antenna can be changed but this affects the efficiency, a smaller antenna gives worse efficiency and the other way around. An advantage with the loop antenna is that it responds to the magnetic field component of an electromagnetic wave. Therefore, the risk of interference between the loop antenna and another antenna in the mobile device may be relatively low (Perlos patent application SE0403110-0 includes the advantages of 42
using an H-field antenna together with an E-field antenna). Another advantage with this solution is the narrow bandwidth that gives a function like a filter, which also lowers the risk for interference. Disadvantages with this antenna are the complexity with the control signal and that it cannot be placed over a ground plane in a cell phone. This means that the loop antenna must be placed on an external flap to have good performance. Another disadvantage is that the control signal must be very precise to tune in exactly right frequency, because the bandwidth is not much wider than the channel. 4.7 Switched Monopole Today nobody wants an external antenna on a mobile phone. Therefore this embedded prototype antenna was designed. With today’s small mobile phones it is hard to achieve required bandwidth for DVB-H with an embedded antenna. The solution to this problem is a switched monopole antenna along one of the sides of a mobile handset. The idea to this solution came from Perlos patent SE525069. The antenna is controlled by two switches/multiplexers so different matching circuits can be connected, a model with three matching circuits is presented in figure 4.18. Figure 4.18. Model of switched monopole concept. The idea of this antenna type is that some different matching circuits together can cover the whole DVB-H frequency band as shown in figure 4.19 The number of matching circuits needed depends on the antenna requirements, but to be sure that the requirements will be fulfilled four matching circuits have been used for all switched monopoles in this chapter. 43
Page 1 and 2: Design of Antennas for Handheld DVB
Page 3 and 4: Acknowledgements This master thesis
Page 5 and 6: 4 DESIGN AND TESTING OF ANTENNA SOL
Page 7 and 8: Figure 5.2. Reference dipole antenn
Page 9 and 10: 1 Introduction The passed decade th
Page 11 and 12: 2 Background This chapter provides
Page 13 and 14: is simultaneously modulated into 10
Page 15 and 16: 2.1.3 Reed-Solomon Codes 2.1.4 DVB-
Page 17 and 18: 2.1.5 DVB-H DVB-H is the latest dev
Page 19 and 20: 2.1.5.2 Time slicing A large proble
Page 21 and 22: figure 2.5). All three elements tog
Page 23 and 24: symbols or four 2K OFDM symbols. Th
Page 25 and 26: 2.2 Competing standards The DVB-H s
Page 27 and 28: 2.3 Antenna theory This section des
Page 29 and 30: Figure 2.9. Impedance bandwidth def
Page 31 and 32: unloaded quality factor (Q0) and th
Page 33 and 34: losses should be avoided in handhel
Page 35 and 36: 3.3 Loop Figure 3.1. Yagi-Uda anten
Page 37 and 38: PIFA Figure 3.2. Four different con
Page 39 and 40: The size of the antenna is another
Page 41 and 42: 4.4 PIFA To verify the balun a resi
Page 43 and 44: 4.5 Folded-Patch With the PIFA-ante
Page 45 and 46: Figure 4.9a. Folded-patch 2, front
Page 47 and 48: Figure 4.11. Loop antenna schematic
Page 49: Figure 4.15. Wire loop antenna retu
Page 53 and 54: antenna. The dimension of the anten
Page 55 and 56: The result of the return loss measu
Page 57 and 58: Figure 4.24. Return loss graph for
Page 59 and 60: The result of the measurement of th
Page 61 and 62: Figure 4.31. Return loss graph for
Page 63 and 64: frequency band, the first from 470
Page 65 and 66: Figure 5.6. Radiation pattern for R
Page 67 and 68: 5.1.3 Measurement result In this ch
Page 69 and 70: Figure 5.10. Radiation pattern for
Page 73 and 74: Table 5.4. Switched monopole 1, gai
Page 75 and 76: Power gain / dB 2 0 -2 -4 -6 -8 -10
Page 79 and 80: was received in all five channels.
Page 81 and 82: 6.3 Control signal 6.4 Cost The swi
Page 83 and 84: not be possible, there will always
Page 85 and 86: There are many advantages with tuna
Page 87 and 88: 8 References [1] Schiller, Jochen -
Page 89: [29] Gardiol, Fred - Microstrip cir

Design of Antennas for Handheld DVB-H ... - Lunds tekniska högskola

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