Electronics > Beginners
Why is antenna size/design less critical for receivers then transmitters?
(1/3) > >>
joeyjoejoe:
I think I've noticed that in general, antennas for RF Transmitters are much more challenging then receivers.

For instance, evaluation boards for two ISM IC's, TX and RX - the TX is very specific and has application notes on the antenna on the design and constraints. The RX is just a big copper rectangle. I've also seen this pattern elsewhere - 433MHZ ISM breakouts I have, the antennas are different. SDR sites saying that generally for receiving, the antenna isn't as important until you get into transmitting...

Is this accurate, and if so why is it the case?
Benta:
There are several answers to this.
For low power ISM transmitters, it's a question of efficiency. You want to translate as much supply power as possible to "air power". The receivers do not have an efficiency issue, they'll consume as much power as needed, regardless of antenna design.
For higher power transmitters an additional problem arises. If the antenna is not correctly matched, you get what's called a bad standing wave ratio (SWR). This means, that RF power not radiated by the antenna is reflected back into the transmitter power stage, worst case causing it to fail or even blow up.

joeyjoejoe:
So is it more a question of "good enough" for RX? Sure, they could spend more hours designing an antenna, but the gain would be a few percent, without any real negative effects. TX the time has to be spent to minimize the negative effects, and as a result we also get a nicely tuned antenna?
Benta:
Yes, it's a question of "good enough" for Rx. Most ISM networks are not range limited. Same with, eg, FM receivers, where the network of transmitters is normally dense enough.
In certain applications like long range WLAN you'll see small parabolic antennas on both ends.

tautech:
It ain't rocket science to achieve good results with the right tools and a little bit of knowledge.
The type of antenna (and good design) used is key so to the use of all of the TX power available so particularly SWR is minimized.
This will give you the basics of what to aim for:
https://www.eevblog.com/forum/rf-microwave/antenna-project-log/
Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod