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Topic Title: Same Antenna for transmission and reception
Topic Summary: What will its size be?
Created On: 30 May 2012 07:17 PM
Status: Read Only
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 30 May 2012 07:17 PM
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ubercool

Posts: 19
Joined: 11 September 2011

Can a same antenna be used for transmission and reception when the transmission and reply frequencies are 63Mhz apart?
 31 May 2012 12:16 PM
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haguetim

Posts: 109
Joined: 25 April 2006

Yes in principle, Are you wanting to receive and transmit at the same time?.
Regarding the actual antenna the most simple method of producing a dual band unit is to run two quarter wavelengths of wire on the outside of a tube spaced apart, trim the lowest frequency leg for minimum return loss then the higher frequency leg to follow.

If you are wanting to Tx and Rx at the same time you will need some sort of filter in the Rx leg, depending on frequency cavity filters are not difficult to make, depending on the power transmitted you may get away with some open circuit quaterwave stubs tuned for the Rx frequency..

If you let me know what frequencies you need I'll calculate the lengths for you.
 31 May 2012 03:53 PM
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cblackha

Posts: 79
Joined: 21 January 2003

Almost certainly - though what it 63 MHz as a % of the lower frequency?

GSM devices use same antenna for 850/900 and 1800/1900 by designing resonances.

There are plenty of devices operating above 2 GHz with TX/RX seperation on 100 MHz or more because antenna works sufficientlyn well at cF +/- 5 or 10%

You might have more trouble with an antenna working at 100 kHz and 63.1 MHz though
 31 May 2012 04:14 PM
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rar

Posts: 642
Joined: 30 August 2005

A log periodic
 04 June 2012 05:11 PM
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zerocred

Posts: 15
Joined: 06 December 2006

It depends. What frequency is being transmitted, the power, how many channels bandwidth of channels, the recieve bandwidth and sensitivity etc. If multiple carriers it could be intermod city.

Everyone always forgets about the uplink.
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