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antenna help...

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flashmanic

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hey professionals...

i am a student...i had to work on a signal processing project...anyhow i jus decided to build a low cost mobile detector..

i just took an antenna from a fm radio and attached it to a bandpass filter (range 890 mhz to 960 mhz). i built the 2 pole bandpass filter using some pots, 2 741's and a couple of resistors n capacitors...

i set it up on a breadboard,the prob now is that although it seems to detect incomin or outgoing mobile signals, its range is rather weak. just maybe 2 metres radius max....can some one tell me how to boost its receiving range...not too much, i want it to detect maybe arnd a 4-5 metre radius detecting range...
 

flashmanic

New Member
well, electronics products are better, but i m tryin to build it with some simple components...coz my project requirements are such tht i should not use ready made products...

and to the earlier question....by electronic components i mean basic amp ics, resistors, capacitors, etc...
 

flashmanic

New Member
well, i just want to show an o/p on the CRO. when i had tried the circuit on a breadboard earlier in my college lab, it showed square waves as o/p in the CRO whenever i made a call or recieved a call...which is exactly i wanted...but i wanted to increase the recieving range...i will attach the circuit design shortly...
 

flashmanic

New Member
initially i used a disc capacitor of value 1pf with short lead length to make it act a mini ghz loop antenna....i attached the o/p of the capacitor to the inputs of the CA3130...whose o/p i then connected to a BC548 to further amplify the i/p signal...although this also worked, its range was horrible and it could detect a single frequency and not a range of frequency....

so therefore i had to resort to the current design...
 
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