Type of trimmer for RFID gate antenna

[sr_raval]

rfid gate

i am designing RFID gate antenna for 13.56MHz,can you suggest me what type of trimmer capacitor are preferable to tune the antenna?power rating approx 8W

 

[FvM]

gate antenna

You should mainly be worried about sufficient voltage rating for the capacitor, several 100 volts are probably required.

 

[sr_raval]

rfid gate antenna

firstly thanks for reply but i know about voltage rating,but i am confused about the type of trimmer,see there are lots of trimmer capacitor available in market like air gap trimmer,mica, Teflon and other more,so from that what would be the suggestible for RFID gate antenna.

 

[FvM]

rfid antenna types

Calculate or measure the maximum voltage at the resonant circuit in tuned case and check the trimmer capacitor datasheets for voltage ratings.

 

[sr_raval]

trimmer airgap

i know the voltage rating,but i am asking for the type of capacitor as capacitor available in different type,like mica,air gap,ceramic and other more,but i am confused that what type of trimmer i will use for my gate antenna ,as antenna works on 13.56MHz,power rating is near 8W

 

[FvM]

working gate antenna

Any trimmer with sufficient voltage rating should work. Unfortunately, I'm unable to guess the voltage level present in your resonant circuit. I have 50 V even in a mW level ISO 14443 RFID reader.

 

[sr_raval]

how rfid antenna works

voltage level in around 200V,can i connect any type of trimmer in tuning circuit,as per my knowledge air gap is better but i am not sure about that that is why i posted this.help me if any body have worked on RFID gate antenna

 

[FvM]

trimmer capacitor voltage power rating

voltage level in around 200V

Finally a piece of information after one week...

There's a TI application for a similar ISO 15693 antenna, they are using mica (10-80 pF) and air gap (3 - 15 pF) capacitors, without specifying a manufacturer or a voltage rating. A teflon capacitor with sufficient dielectrica thickness should work, too. But it's better to have a manufacturer voltage rating, I think.

 

[sr_raval]

15693 antenna

I have already refer that TI document,but that is for small loop antenna,we can not consider that parameter for gate antenna as gate antenna have high output power but small loop antenna only working on 200mw,you have design gate antenna any time???

 

[FvM]

antenna design gate

The TI application note tells about at least 6W output power, thus it's comparable, I think.

I know, that you can get Mica trimmer capacitors with a 2.5 kV DC voltage rating, usable e.g. for valve PAs, they should work anyway.