dc out pad for antenna output

[aniakhan]

hi,
i want to make a circuit for detector and the paper which i have studied they have used a dc out pad for out put ,can any body guide me what does it mean by dc pad here?please i am new for fabrication of antenna.i am attaching the paper.thanks

 

[jiripolivka]

The "DC pad" described in the paper is a device (a capacitor or a quarter-wave section) allowing the DC output to be taken from the detector diode. Any detector must have such "DC pad" if you want to operate its diode.

 

[aniakhan]

thanks jiripolivka ,so it means i should either connect diode which is mounted on antenna to a capacitor so that it behaves like load to diode output??or i should use lembda/4 transmission line???sorry to repeat the same answer but i want to confirm either i amright in understanding your answer??thanks for answer. also in another paper they have fabricated dc pad on arm of antenna how can it be done with capacitor???i am attaching that paper too,please have a look on first figure then if you get it please guide me,i am not understanding dc pad circuit connection.
thanks

 

[jiripolivka]

thanks jiripolivka ,so it means i should either connect diode which is mounted on antenna to a capacitor so that it behaves like load to diode output??or i should use lembda/4 transmission line???sorry to repeat the same answer but i want to confirm either i amright in understanding your answer??thanks for answer. also in another paper they have fabricated dc pad on arm of antenna how can it be done with capacitor???i am attaching that paper too,please have a look on first figure then if you get it please guide me,i am not understanding dc pad circuit connection.
thanks

You must design a DC current loop for a diode to operate it, as a detector or mixer. Without the DC loop a diode cannot function. The papers show some solutions.
The diode is connected between ground and RF power is applied to it. The diode functions as a rectifier, so you need to get all RF power to it while you need to run the rectified DC current through the DC loop.
Did you ever build a crystal radio? This is a good start to understand how a diode detector operates.

 

[aniakhan]

thanks jiripolivka for your help,it really helped me to understand it