Thanks all, appreciate the info.
Greg.


Richard Harrison wrote:
Greg wrote:
"Anyone know the formula (if there is one) for working out the spacing
of the elemrnts on a UHF TV antenna?"

It`s a choice, not a formula, because of many tradeoffs.

There are many types of TV antennas For a particular frequency, Kraus
shows a Yagi on page 66 of his 3rd edition of "Antennas" which spaces
the reflector 1/4-wave behind the driven element, and (4) directors are
used ahead of the driven element. Each director is spaced at a distance
of WL/pi from its neighbors. This gives 15% bandwidth, plenty for a
single TV channel, even for Channel 2 at 50 MHz.

The UHF TV channels extend from about 500 to 800 MHz. 633 MHz would
would be the geometric mean frequency. 95 Mhz would be the antenna
bandwidth at 633 MHz.

The geometric mean of two numbers is the square root of their product

There are many tradeoffs in TV antenna design. Look at some good book
concerning the subject such as "TV and Other Receiving Antennas" by
Arnold B. Bailey. Chapter 12 deals with "Practical Aspects of TV
Receiving Antennas.

Best regards, Richard Harrison, KB5WZI