Antenna question

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zachtheterrible

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This is the artwork for a 900MHZ transmitter using a pre-built RF module. The pins lined up horizontally is where the circuit plugs in. The last pin on the right is the antenna pin. The antenna is a whip antenna. I have quick question:

Did I do it correctly? The datasheet said that there should be a groundplane horizontal to the vertical antenna, which is a piece of wire in this case.
 

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Perhaps you might have made the picture somewhat smaller?.

The groundplane refers to a solid sheet of copper on the upper surface of the board, connected through to the ground points on the bottom - so you require a double sided board. However, you don't need to etch the top surface, you can simple countersink the holes where the components pass through.
 
Sorry about the picture, I realized how large it was after i posted it :lol:

The large portion of copper on the bottom of my board is ground. Wouldn't this count as a groundplane to my antenna?
 
Your groound plane should be at least 1/4 wavelength. But, Yageo makes a ceramic antenna that does not need a ground plane. Mouser sells it for $7.65. If it works as good as the 433 mHz antenna that I bought, it will be as good or better than a 1/4 wave whip (but I think it is directional).
 
I don't have room for 1/4 wavelength, that would be 3 inches @ 900 MHZ.

Oh yes, another question: I am using a 1/2 wavelength antenna. I assume there's nothing wrong with that.
 
The transmitter is no doubt designed to drive 75 ohms, the 1/2 wave antenna, when end driven, is high impedance. You will not have any radiated power. The Yageo antenna will be much smaller than 3 inches, the 433 mHz antenna was no more than 2 1/2 inches long.
 
zachtheterrible said:
Sorry about the picture, I realized how large it was after i posted it :lol:
Zach, don't you use the preview button? It's particularly useful when you're adding an attachment.
 
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