Antenna Power

[jamesb]

Hi,

I'm new to this forum, and haven't done anything specifically HAM related for a long time (hoping to remedy it).

I'm building a 430Mhz transceiver for a remote controlled vehicle at the moment, and have a quick question relating to the antenna...

I want to make a half-wave dipole circa 1 ft long from a copper tube, and wondered if there will be a problem driving this from a relatively low power source (range doesn't *need* to be more than 15m, although about 100 would be nice). I'm a bit (very) rusty on antennas as it isn't an area i've worked with much. Would it be a simple case of adding an amplifier between the Tx output and the antenna connection? (I'm hoping by having maximum efficiency on the Tx module, I can use a much smaller & lower performance receiving antenna in order to save weight)

Thanks for any input

[K7KBN]

Hi,

I'm new to this forum, and haven't done anything specifically HAM related for a long time (hoping to remedy it).

I'm building a 430Mhz transceiver for a remote controlled vehicle at the moment, and have a quick question relating to the antenna...

I want to make a half-wave dipole circa 1 ft long from a copper tube, good choice for lengthand wondered if there will be a problem driving this from a relatively low power source no problem. Use a short piece of very good coaxial cable. (range doesn't *need* to be more than 15m, although about 100 would be nice). I'm a bit (very) rusty on antennas as it isn't an area i've worked with much. Would it be a simple case of adding an amplifier between the Tx output and the antenna connection? If you need the extra power (I'm hoping by having maximum efficiency on the Tx module, I can use a much smaller & lower performance receiving antenna in order to save weight) You can use the same antenna for receiving, although you don't say whether you're using a separate transmitter and receiver, or a transceiver. You will probably have better range if you position the dipole to match the position of the antenna on the R/C vehicle. Experiment for best results.

Thanks for any input

[5B4AJB]

I mounted a rubber duck with a BNC socket on my R/C car, it never broke when I rolled it, which was quite a bit...

A simple 2W linear & filter should be easy enough to knock up for the transmitter...

[jamesb]

Thanks guys,

Think I'll go for 1/2 or 1/4 wave coaxial dipole, and then just use an amplifier if I'm not quite getting the range. :)

[K7KBN]

A "dipole", by definition, is 1/2 wavelength overall. Don't try a 1/4 wave dipole; feedpoint impedance through the roof. Stick with odd multiples of 1/2 wavelengths for dipoles (1/2, 3/2, 5/2, etc).

Now, a 1/4 wavelength ground plane is another matter entirely.