Ham Radio Antenna Design Notes: Difference between revisions
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Created page with " === resonance / swr === === Q === === Impedance === === Common Mode Current === === Velocity Factor === == Math == === 492 / Freq in MHz === === 1005 / MHz ===" |
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== 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 20:57, 29 July 2017
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