Difference between revisions of "Ham Radio Antenna Design Notes"
From Free Knowledge Base- The DUCK Project: information for everyone
(Created page with " === resonance / swr === === Q === === Impedance === === Common Mode Current === === Velocity Factor === == Math == === 492 / Freq in MHz === === 1005 / MHz ===") |
m (→1005 / MHz) |
||
| (4 intermediate revisions by one user not shown) | |||
| Line 1: | Line 1: | ||
| − | + | == Considerations in Design == | |
=== resonance / swr === | === resonance / swr === | ||
| Line 14: | Line 14: | ||
=== 492 / Freq in MHz === | === 492 / Freq in MHz === | ||
| + | |||
| + | Calculate length for an inverted V antenna. | ||
=== 1005 / MHz === | === 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 | ||
Latest revision as of 21:57, 29 July 2017
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
