Tham khảo tài liệu 'advanced transmission techniques in wimax part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CPW-Fed Antennas for WiFi and WiMAX 41 plate is a useful modification of the corner reflector. To reduce overall dimensions of a large corner reflector the vertex can be cut off and replaced with the horizontal flat reflector Wc1xWc3 . The geometry of the proposed wideband CPW-fed slot antenna using A-shaped reflector with the horizontal plate is shown in Fig. 27 c . The A-shaped reflector having a horizontal flat section dimension of Wc1xWc3 is bent with a bent angle of p. The width of the bent section of the A-shaped reflector is Wc2. The distance between the antenna and the flat section is hc. For the last reflector we modified the conductor reflector shape. Instead of the A-shaped reflector we took the conductor reflector to have the form of an inverted A-shaped reflector. The geometry of the inverted A-shaped reflector with the horizontal plate is shown in Fig. 27 d . The inverted A-shaped reflector having a horizontal flat section dimension of Wd1xWd3 is bent with a bent angle of a. The width of the bent section of the inverted A-shaped reflector is Wd2. The distance between the antenna and the flat section is hd. Several parameters have been reported in Akkaraekthalin et al. 2007 . In this section three typical cases are investigated i the A-shaped reflector with he 30 mm p 150 Wc1 200 mm Wc2 44 mm beamwidth in H-plane around 72 as called 72 DegAnt ii the A-shaped reflector with hc 30 mm p 150 Wc1 72 mm Wc2 44 mm beamwidth in H-plane around 90 as called 90 DegAnt and iii the inverted A-shaped reflector with hd 50 mm a 120 Wd1 72 mm Wd2 44 mm beamwidth in H-plane around 120 as called 120 DegAnt. The prototypes of the proposed antennas were constructed as shown in Fig. 28. Fig. 29 shows the measured return losses of the proposed antenna. The 10-dB bandwidth is about 69 to GHz of 72DegAnt. A very wide impedance bandwidth of 73 GHz for the antenna of 90DegAnt was achieved. The last impedance bandwidth is 49 to GHz when the antenna is
