Broadband antenna and matching techniques
Contents Introduction Biconical antenna Triangular sheet, Bow-tie, and wire simulation Cylindrical dipole Folded dipole Discone and conical skirt monopole Sleeve dipole Matching techniques
Fundamental limit of BW The band width of an antenna (which can be enclosed in a sphere of radius r) can be improved only if the antenna utilizes efficiently, with its geometrical configuration, the available volume within the sphere
Biconical antenna Dominant TEM mode
The input impedance is independent of frequency.
Triangular sheet, bow-tie, wire simulation
Cylindrical dipole Thick dipole has broad band characteristics.
Equivalent radii
Folded dipole FM broadcasting receiving (88~ 108MHz). TV antenna (54~ 216MHz)
Equivalent circuit of folded dipole
Matching techniques
Balun and transformers
Type I or “bazooka” balun