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Antenna question

 

Hello,

I have a question: Are these setups equivalent (radiation-wise)?

Purple: Portable antenna for, say, 10 m (think of a GRA-1899T)
Blue: Ground/radial of 2.5 m
Black: Yaesu

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Daniel PY2TDB.
 

Daniel:

If black is the radio, which is about 20 cm, they are functionally equivalent. ?Neither is optimal, however due to the radiator of the antenna you described being shortened by about 1/3 relative to a 1/4-wave radiator and there being only one radial. A few more radials in this configuration could add a few more dB to your signal. Basically, with one radial, you're cutting effective power to less than a third. I'm assuming a vertical radiator and 1/4 wave radial at 90 degrees.?
?

Number of 1/4λ Radials and approximate?ERP?

  • 1 radial: ?? x ~0.35 power (puts out about 1/3 of what goes in assuming a 1/4 wave radiator and other optimum conditions)
  • 2 radials: ?x ~0.45?
  • 4 radials: ?x ~0.65
  • 8 radials: ? x ~0.85
Jim
WB0KWJ
?
 

Wow..I didn't know it was so lossy! Out of curiosity: the case of one radiator, where does the 2/3 of the power go?

Daniel PY2TDB.


Em dom., 9 de mar. de 2025, 17:06, James Todd via <toddjam=[email protected]> escreveu:

Daniel:

If black is the radio, which is about 20 cm, they are functionally equivalent.? Neither is optimal, however due to the radiator of the antenna you described being shortened by about 1/3 relative to a 1/4-wave radiator and there being only one radial. A few more radials in this configuration could add a few more dB to your signal. Basically, with one radial, you're cutting effective power to less than a third. I'm assuming a vertical radiator and 1/4 wave radial at 90 degrees.?
?

Number of 1/4λ Radials and approximate?ERP?

  • 1 radial: ?? x ~0.35 power (puts out about 1/3 of what goes in assuming a 1/4 wave radiator and other optimum conditions)
  • 2 radials: ?x ~0.45?
  • 4 radials: ?x ~0.65
  • 8 radials: ? x ~0.85
Jim
WB0KWJ
?
 

Mostly heat in the transmission line and finals. If it's an antenna with radials on the ground, resistive ground losses. ?
 

Daniel.
?
The answer to your question is? yes,, both the setups you sho
will essentially work the same.
?
73, Bob GM4CID

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