Both E- and H-plane radiation patter
Beamwidth
• Half power beamwidth θdB 3 E-plane beamwidth, H-plane beamwidth • The wider θdB beamwidth the 3 wider angular coverage • The widerθdB beamwidth the 3 more interferences input to the receiver
Radiation Pattern with Center Driving
這是場型圖， 請注意不同 gain值的場 型
•The definition of dBi is the antenna gain which compares to that of the isotropic antenna •The definition of dBd is the antenna gain which compares to that of the dipole antenna •The directivity of half wavelength dipole is 2.15 dBi •The directivity of 1.25 (2x0.625) wavelength dipole 5.16 dBi
dB = −10 log 1 − Γ
(
2
)
VSWR與Return Loss的關係是互換關係，若 VSWR是2.0:1,則相對於Return Loss是約10dB，其意是發射出去有90%的功率，反射回 來有10%，反射愈多，幅射效率愈差
• Examples
VSWR=1.5, Γ = 0.20 , RL=14 dB, TL=0.177 dB VSWR=2.0, Γ = 0.33 , RL=9.5 dB, TL=0.512 dB VSWR=3.0, Γ = 0.50 , RL=6.0 dB, TL=1.24 dB
