Tuesday, 21 June 2011

Advantages of EFHWA over Dipole antenna

All the discussions pertaining to EFHWA and the ZS6U Mini Shack Special might create unrealistic expectations of the performance of one being better than the other.

A dipole antenna is a dipole antenna. It does not matter if the dipole or ½ wave length wire is fed at the center or at the end or anywhere in between. The only difference is the impedance at the feed point.

In the case of the traditional center fed dipole it has an impedance of around 70 Ohms and that normally suits us nicely with a reasonably good match between the antenna and the coaxial feed line and our transceivers without the need of an ATU.

When the same ½ wave length antenna is fed at the end as in the EFHWA then the impedance is very high in the order of 5000 Ohms. This in turn means we must use some form of antenna matching unit to transform the impedance to 50 Ohms.

What is the advantage of the end fed half wave antenna (EFHWA)??

An EFHWA cut for 40m is approximately 20.8 metres long and will work on the 40, 20, 15 and 10 metre bands and on 80 m at a push. The normal center fed dipole of the same length will work on 40m and on 15m at a push, and that is all.

The EFHWA does not require a feed line. In ultra light portable operation this is a big issue. The coaxial feed line is heavy and cumbersome.

Colin mentions that the capture area advantages and I tend to agree with that thinking as well.

When using the EFHWA we must still strive to place it as high above the ground and clear of surrounding objects as possible.

There is no free lunch !!


  1. Hi Pierre,

    My favourite RaDAR antenna is very similar. A +- 20m length of wire wired to a 4:1 balun.

    I have a short (1.5m) length of RG58CU from the balun to a z817 ATU.

    I do wire two short "Radials" (About 2 meters of wire) to the earth side of the balun and let these wires just lie on the ground as a "Return path".

    I need to experiment with different configurations to find improvements if any? This antenna arrangement has proved to work well during a few tests done.

    73 Eddie ZS6BNE

  2. Another advantage of the EFHW is it can be supported by a kite. I have used it QRP portable this way a few times with good results.
    Ray WD5DHK

  3. Ray,

    I agree 100%

    I have had the pleasure of having a 2 way QRP QSO with Dean ZD8DC (N2WE) from Ascension Island. Dean was basically using an end fed antenna half wave antenna supported by a kite.

    A most memorable QSO recorded in my log.

    73, Pierre