Tad Danley wrote:
I have started to experiment with EZNEC and am modeling a couple of loop
antennas including some delta loops. I see references to hams using 4:1
baluns with these antennas, but the models I see show a feed point
impedance of roughly 100 ohms. I'm not sure how a 4:1 balun would help
- what am I missing?

Thanks and 73,

Tad Danley, K3TD

Tad:

A 2:1 construction of a "true" 2:1 balun is possible, however, driving a
100 ohm loop from 50 ohm coax does NOT require one--meaning, a 2:1 "RF
TRANSFORMER" will suit your purposes, more than adequately.

The winding to the 50 ohm source will be half the turns of the 100 ohm
winding--and there is no electrical connection between windings--i.e.,
the 50 and 100 windings are separate on the core.

The turns will depend on the core material/power/freqs of your intended
use ...

However, the focus here is that you DO NOT need a true balun here, since
the loop is inherently free from any adverse influences of using a
voltage balun, a rf transformer is more than adequate for your use--and
will simplify your requirements. You should find adequate construction
data for a "2:1 rf transformer" (separate 50/100 ohm windings) with a
google search ... etc. A ferrite bar or toroid, either, should fit your
purposes, as you choose ...

Regards,
JS