PORTABLE 3 ELEMENT YAGI FOR 2 METRES by Dave, VK2JDS (October 2006)

Design:
This antenna was designed to be taken portable up on hilltops or buildings etc and operated
from a 2 metre handheld.

It can be hand-held on the boom back near the reflector without upsetting the gain or vswr.

Background:
Originally this antenna was designed and assembled with the driven element mounted midway
between the reflector and the director however this didnt work so well , and had a best
vswr exceeding 1.6:1,so much experimentation resulted in the final design which is seemingly
unaffected by handholding the boom or mounting it on hastily made structures while out portable.

The VSWR  curve is thus:

144.1	1.5:1
145.0	1.3:1
146.0	1.2:1
147.0	1.2:1
148.0	1.4:1

Dimensions:

The element lengths are:

Reflector	950mm
Driven		940mm overall
Director	855mm

The spacings are:

Reflector to driven	500mm
Driven to director	330mm

Driven element details:

The driven element consists of 2 pieces of 10mm aluminium tubing mounted on a piece of perspex.
2  holes are drilled through each element to mount them onto the perspex and they are fixed
with 3/16" machine screws and nuts. The perspex is then mounted to the boom with 2 longer 3/16"
screws and nuts.You can utilise whatever bolts you have available, otherwise visit the local
hardware store.

Testing:
This antenna works very well against a omnidirectional antenna, its light, small and using thin
coax scrounged from mobile phone instalations its excellent for useage out-bush.

Refer to the pictures for more detail.

1. the antenna


2. the feedpoint