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rf bandpass filters 2.4GHz

Hi all,

I am transmitting in channel 3 of 802.11b, centered at 2.422Ghz. Details aside, let me just say that it is very important for my application that I sharpen up the spectral mask beyond that of the

802.11b standard. To be specific I need to purchase a bandpass filter such that I get attenation of greater than 60dB at +- 15Mhz from the center, i..e outside of [2.407Ghz, 2.437Ghz]. I am looking for suggestions on where to purchase such filter(s) with the usual parameters in mind, cost, lead time, etc.

I did see the filters that hyperlink sells, but it would take many of their 8 pole filters in series to get what I need and they additionally don't sell filters for one of the channels i would need. Maybe I need to go custom on this? Any suggestions are greatly appreciated. Thanks,

Kevin

Reply to
kevin.pavin
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You don't need to go custom. You need to understand the impossibility of what you are asking for. Jim

Maybe I need

Reply to
RST Engineering (jw)

The centerfrequency divided by the bandwidth gives the Q value. The "bandwidth" means -3db. 30MHz at

2.4GHz would result in a Q of 80. Now you want -60dB instead of -3dB. That should be doable with a Q of roughly 1600. Right ? A dielectric resonator could do it. Temperature stabilized. The usual parameters : Unless from stock because it is manufactured in high quantities, leadtime 3month up, hand crafted microwave gear costs in the range of military and space items.

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
Reply to
Rene Tschaggelar

Sorry I mispoke earlier. Let me restate this. Hyperlink has an 8pole filter for several of the 802.11b channels that has the mask -3db at +-

10Mhz, -5db at +-15Mhz, -20dB +- 20Mhz.

Essentially I want to keep 2.417 to 2.437 Ghz, so one of their filters centered at 802.11b, channel 4 would be ideal, except that they only sell centered at the standard channels (channel 3 and 6 are the closest), so in short I was wondering if anyone knows of a vendor that sells such a filter centered at 2.427Ghz. Thanks for any suggestions.

RST Eng> You don't need to go custom. You need to understand the impossibility of

Reply to
kevin.pavin

Hello Rene,

Well, one could start with cavity resonators. But they would have to be regularly tuned and you'd needs lots of polishing paste and elbow grease. Plus a good medical insurance plan to deal with "tennis elbow".

--
Regards, Joerg

http://www.analogconsultants.com
Reply to
Joerg

Hello Kevin,

That looks like you'd have to call them for a custom version which will probably be lots of $$. Or roll your own which requires a lot of RF/microwave knowledge. Or hire a consultant :-)

Problem is, if you are most likely the only one needing this there won't be an existing market and chances that any other company has the right product could be close to zilch.

--
Regards, Joerg

http://www.analogconsultants.com
Reply to
Joerg

Joerg, a Q of 1600 in the S Band is not that extreme, or is it ?

Rene

Reply to
Rene Tschaggelar

Can't you do this at IF?

Tam

Reply to
Tam/WB2TT

He might with a hi Q cavity.

--
Baron:
Reply to
Baron

Hello Rene,

It is amazing what can be done with cavity resonators but for this job it needs to be high precision and multi-stage. An example of how they look in the professional world is shown on page 7-4:

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Sorry, the text is only available in German which you'll understand but the others here may not. My other sources for hi-Q resonators are also all German, such as the most excellent hands-on book series "UHF Unterlage". That'll show you step by step how to build them. But don't even think about it if you don't have access to a precision lathe ;-)

--
Regards, Joerg

http://www.analogconsultants.com
Reply to
Joerg

Perhaps you could get one of the hyperlink models and modify it.

Reply to
Jimmie D

Send your spec to these guys, they should be able to help you or at least tell you whether it can be done. I hope you can afford their products. Their tunable notch filters are very nice and might be one way of avoiding a custom design, though I don't know if they cover your frequency.

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Reply to
Chris Jones

Hello Chris,

And if Kevin decides to build it himself he'll need really good polishing paste. My trusty "Wenol" paste ran out a while ago and a few days ago I found it: At an upscale kitchen store!

(Such pastes are not healthy, make sure it doesn't get on the skin)

--
Regards, Joerg

http://www.analogconsultants.com
Reply to
Joerg

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