5

I understand that in a half-wave center-fed antenna current distribution has a sinusoidal wave approximately, so the current in the center has max value and it has to become zero at the ends of dipole which are open. But since we change the feed point from center to one of the end points, the current in feed point (the end of antenna) is not zero this time right? So it seems that moving feed point from center to end change the current distribution.

My question is how to calculate current distribution in theory in this new arrangement. I am familiar with Hallen integral equation and method of moment, but in this method we use boundary condition of current which is zero in both ends. However, in end-fed dipole it seems we do not have this boundary condition in one end.

So what should I do? Or in general how can I calculate current on dipole antenna?

Mike Waters
  • 8,201
  • 4
  • 19
  • 51
M.D
  • 51
  • 1

2 Answers2

1

M-o-M software such as NEC (Numerical Electromagnetics Code) is capable of calculating the distribution and values of r-f currents along radiating conductors.

The graphic below shows the distribution of such current along the conductors of an "end-fed" antenna system, for the parameters and configuration described there.

The value of r-f current at each segment of the antenna conductors is available from the calculated results, but that data is omitted in this post.

enter image description here

Richard Fry
  • 2,950
  • 8
  • 19
0

Perhaps the following graph based on EZNEC simulation data will allow the development of an empirical curve-fitting formula. Note that the current envelope is very similar to one half of a Double Zepp. Current Magnitude and Phase for an End Fed Dipole simulated in EZNEC

Cecil - W5DXP
  • 1,684
  • 7
  • 8