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