|
|
VK3KHB
Antenna Designs...
Below are some simple antenna
designs I have made and used with good results. They are all decades
old now but still usable. Antenna are one of those fundamental tools
that only improve with better material technology the underlying design
remains the same, reflector, radiator and directors all on a boom and
all made to a specific frequency / band. All antenna will weather and
it just how well the object is made and from what materials that will
limit it's expected usable life.
To transmit and receive amateur television signals you need a good
antenna. As ATV operates on several bands you need to know which
antenna is the best to build for each band. For most amateurs this will
be the 23cm band (1241-1392Mhz) or 70cm (425-450).
In melbourne you'll need a 23cm band yagi or 3cm yagi / dish to
transmit up to the repeater. The 70cm is used for the repeater's output
and a domestic UHF TV antenna usually has enough gain to receive a
reasonably good quality picture and a mast head RF amplifier ~10dB+
gain would really pull the signal out of any noise. You can not use a
domestic TV antenna to transmit on as they are designed for a very
broad frequency band width which makes it very unsuitable for
transmitting.
70cm Band (440Mhz)
8+ element yagi design (1970-80's) in PDF format: 70cmant.pdf 12KB
file to download.
23cm Band (1.2Ghz)
8+ element yagi design (1990's) in PDF format: 23cmant.pdf 18KB
file to download.
13cm Band (2.4Ghz)
Potatoe Chip Pack design (2000's) in JPG format: 13cmant.jpg 220KB
file to download
Original diagram from our friends at http://www.oatleyelectronics.com
|
|