G4zu Hf Beam As Built By Zs1jhg

G4ZU HF Beam as built by ZS1JHG

This antenna has excellent performance on the upper HF bands ie 15m, 12m and 10m. It only acts as a dipole on 20m and 17m. So if 20m is your main DX interest look at the Moxon Beam. Feed with 300 ohm twinfeed (windowline) and 4:1 balun. Then a short length of 50 ohm coax to your transceiver. An ATU is required and this also allows the beam to be used on the WARC bands with good results. The best multiband antenna I have built for 10m so far. My antenna was built with straight Dural tubing ie no tapering of the elements. The Dural is heavy and strong and stood up well to the High winds in winter but needs a very strong boom to mast mount ( suggested : a cast mounting plate) even for tapering elements if you live in a high wind area.

Photos show the element to boom mounts which need to be insulated. The coax attached to the director and reflector are stubs for 10m and 15m with matching coils.

Page2 The drawing gives full details of construction and tuning of the stubs (a GDO was used )

Photo of the elements completed and tuned

Page 3

Photo showing the element to boom mounting

Notice the wood doweling used to insulate the two halves of the elements. Fibreglass rod would be better. The coax stubs (50 ohm RG58c) were strapped to the element (after tuning)with cable ties. Hams make good use of their “Workmate” benches.

Page4

The gain figures quoted are from Eznec. I built this antenna before I found out how to model an antenna and see if will work as claimed. (note poor gain on 20m) Extensive examples and instruction on modelling

Page 5 Antennas is available from L B Cebik`s website

Page 6 Measurements taken of my G4ZU on the tower at 30 feet Using an MFJ 259B Analyzer. Feedline 300 ohm foam twinlead via 4:1 balun to 50 ohm coax. Freq

SWR

R

X

14200

2.8

63

+60

18130

2.7

28

-34

21250

1.5

32

2

24950

1.5

80

0

28500

1.8

66

+31