Question[s]: In the UK, is 433 MHz allocated to Amateur Radio? Simon, in
other words, is a license required for operation on 433 MHz in the UK?

Observation[s]: A yagi receives from ALL directions but has a preferred
direction where it has gain.

Yagis may not meet your requirements for narrow beam. A high gain Yagi
may have a beamwidth of +/-10 degrees or more. A moderate gain Yagi will
have a beamwidth of 30-40 degrees.

DD, W1MCE

Simon wrote:

Hi,
I'm playing around with some 433MHz transmitter and receiver pairs.
Ideally I would like the transmitter to transmit in a narrow
directional beam, but I'm new to the art of radio waves and antenna
design, so I was wondering if you guys would be able to help me with
my project. I've read about a Yagi design for the antenna, I know it
receives from one direction only, but does it transmit in just one
direction too?

I thought I'd be able to basically stick the transmitter antenna in a
tube, sealed at one end, line either the inside or outside of the tube
with tin foil (or both) and it would transmit in whatever direction
the open end was facing. So far my tests haven't been too conclusive
but could that be poor setup on my part or is the idea fundamentally
flawed?

Many thanks for your time,

Simon.