Ham Radio Antenna Design Notes
From Free Knowledge Base- The DUCK Project: information for everyone
Contents
Considerations in Design
resonance / swr
Q
Impedance
Common Mode Current
Velocity Factor
Math
492 / Freq in MHz
Calculate length for an inverted V antenna.
1005 / MHz
Calculate length for a full wave loop antenna.
Talking Points of Experience
Loading coil to simulate length, but inefficient and generates heat, doesn't handle high power well.
DC grounded antennas are ideal: prevents static build up on antenna
Precision in element length becomes more significant at higher frequency
Understand how capacity hats impact resonance
Impedance Dipole vs Inverted V
A dipole in free space should have about 72 ohms of input impedance. As you move the poles down to form and inverted V the impedance lowers.
A folded dipole needs a 4:1 balun
