Registe-se, faça a sua apresentação e terá acesso total ao TX&RX Fórum. ___________________________ Apresente-se dizendo quem é, escreva algo sobre si. Exemplo: Nome, indicativo, nome de estação, localidade, o que mais gosta de fazer no mundo das radio-comunicações e outras coisas que ache importante para a sua apresentação. Se é novato não tenha vergonha de o dizer, pois cá estamos para o ajudar.
___________________________ O TX&RX Fórum destina-se à publicações de mensagens "posts" relacionados com todos os assuntos sobre Radio Frequência. Essas mensagens têm como objectivo promover ideias, experiências, projectos, esclarecer duvidas, divulgação de actividades e publicações de novidades sobre Radio Comunicações.
Divirta-se!!
___________________________ O TX&RX Fórum destina-se à publicações de mensagens "posts" relacionados com todos os assuntos sobre Radio Frequência. Essas mensagens têm como objectivo promover ideias, experiências, projectos, esclarecer duvidas, divulgação de actividades e publicações de novidades sobre Radio Comunicações.
Divirta-se!!
Divulgação
The Random Wire Double Zepp Antenna
TX RX Fórum :: TX&RX Fórum :: HF :: Antenas - HF
Página 1 de 1
The Random Wire Double Zepp Antenna
por ALF007 Qui 14 Abr 2016 - 0:22
[Tens de ter uma conta e sessão iniciada para poderes visualizar esta imagem]
Dipoles fed with an open wire line are called “Double-Zepp” or “Doublet”. The dipole (2 x Xm) may have any length, the open wire feeder (2 x Ym ), too. You can choose the lengths as your local facilities allow.
At the feedpoint Z Z is a random impedance Z, which can be matched to 50 Ohm with an antenna tuner. We must differ three cases:
1. The impedance is very low. That is hard to match and the losses are high.
2. We have impedances from 15-100 +/- j X Ohm. In that case a Balun 1:1 is the right choice for open feeders.
3. We have medium impedances (200-600 +/- j X Ohm). That can be matched without any problems with the most tuners. If you have an asymmetric ATU use a balun 1:4 to match the open wire feeder.
4. The impedance is very high (> 1 KOhm). Most tuners have difficulties and the voltage in the matching system is extreme high.
1 and 4 should be avoided.
But how can we calculate the impedances at Z Z? The first method is “trial and error”. Connect the tuner and try to match the system. In many cases that will be successful, but it may be that some bands cannot be tuned. Then make the feeder shorter or longer and try it again.
- Link
Dipoles fed with an open wire line are called “Double-Zepp” or “Doublet”. The dipole (2 x Xm) may have any length, the open wire feeder (2 x Ym ), too. You can choose the lengths as your local facilities allow.
At the feedpoint Z Z is a random impedance Z, which can be matched to 50 Ohm with an antenna tuner. We must differ three cases:
1. The impedance is very low. That is hard to match and the losses are high.
2. We have impedances from 15-100 +/- j X Ohm. In that case a Balun 1:1 is the right choice for open feeders.
3. We have medium impedances (200-600 +/- j X Ohm). That can be matched without any problems with the most tuners. If you have an asymmetric ATU use a balun 1:4 to match the open wire feeder.
4. The impedance is very high (> 1 KOhm). Most tuners have difficulties and the voltage in the matching system is extreme high.
1 and 4 should be avoided.
But how can we calculate the impedances at Z Z? The first method is “trial and error”. Connect the tuner and try to match the system. In many cases that will be successful, but it may be that some bands cannot be tuned. Then make the feeder shorter or longer and try it again.
- Link
ALF007- Administrador Fundador
Tópicos semelhantes» 2 maneiras de fazer Antena - Random Wire Antenna
» Choosing Wire For An Antenna
» The Double Bazooka Antenna – A Review
» Hybrid Double Quad Antenna 2m 2/HDQ5
» Como partilhar antena de CB e SDR
» Choosing Wire For An Antenna
» The Double Bazooka Antenna – A Review
» Hybrid Double Quad Antenna 2m 2/HDQ5
» Como partilhar antena de CB e SDR
TX RX Fórum :: TX&RX Fórum :: HF :: Antenas - HF
Página 1 de 1
Permissões neste sub-fórum
Não podes responder a tópicos
