Norman Lockyer Observatory Radio Group

GB2NLO G0AXC

  • Increase font size
  • Default font size
  • Decrease font size

NLO Crossed-wire antenna. Simulations for 500KHz (600m)


  

Simple dipole feed:

N and S wires driven.
E and W wires unconnected.

Model: x45_dipole_600m.ez .

Polarisation is horizontal from broadside direction and vertical from end-on.

Radiation pattern is typical for a low electrically short horizontal wire.

Eficiency is low but acceptable.

Zin = 6 - j1400 Ω at 500KHz
A large series loading inductance will be required in the antenna matching network (further reducing the efficiency).

 

 

Splayed dipole feed:
Field strength pattern is practically identical to simple dipole but rotated through 45°.

Model: x45_splay_600m .
Zin = 3 - j700 Ω at 500KHz
Max gain: -13dBi.

N+W driven against S+E gives vertical polarisation in NW - SE Direction (end on) and horizontal polarisation in SW-NE direction (broadside).

 

 

Double-T feed:
Strapping the antenna to make two long wires which cross at the centre, and driving the two wires in opposition, produces a null in the vertical direction.
Model: x45_2T_600m.ez .
Zin = 2.4 - j730 Ω at 500KHz
The disadvantage of this configuration for 500KHz working is extremely low efficiency (max gain: -37.4dBi).

Polarisation is vertical in N-S and E-W directions (looking end-on to either wire), and Horizontal in NE-SW and NW-SE directions.

 

 

 

DWK 2008