>-----Original Message-----
>From: [email protected] [mailto:[email protected]]
>Sent: Tuesday, September 10, 2002 6:07 AM
>To: [email protected]
>Subject: FCC Testing 2.45 GHz Transmitter
>
>
>
>Consider a 1W frequency hopping, spread spectrum transmitter
>operating at
>2.45 GHz. The FCC released a Public Notice on acceptable test methods
>(Filing and Measurement Guidelines for Frequency Hopping
>Spread Spectrum
>Systems) where they "recommend" that the spurious radiated
>emissions in the
>restricted bands are to be measured with a high pass filter. There is a
>restricted band at 2483.5-2500 MHz. Given a 1W transmitter and
>a spurious
>limit of 500 uV/m at 3 m, it would seem that I need a very
>sharp high pass
>filter or a very good notch filter to measure in that band. Is this
>feasible?
>
>It would also seem that a notch filter or low pass filter is
>required for
>measuring spurious emissions in the restricted bands below
>2.45 GHz. There
>is a restricted band at 2310-2390 MHz. Again, is a filter feasible?
>
>I am aware of semi-custom filter suppliers, but are there any
>off-the-shelf
>filters available?
>
>Richard Woods
>Sensormatic Electronics
>Tyco International
>
Rich:
I use tunable band-reject filters from K & L Microwave,
http://www.klmicrowave.com/ , for the type of measurements you are
describing. Typically, their BR filters have a 5% wide rejection notch that
is about 50 dB "deep". The mechanical tuning is sensitive and "touchy". You
still may not get a steep enough slope for your frequencies, but it's the
best I can think of. I also have a couple of custom-made HP filters from K&W
Microwave, at http://www.kwmicrowave.com/ , which I use for one of our
product lines that has a 20 watt emitter at 226 MHz.
I also keep a selection of HP, BP & LP filters, which are flatter or have a
wider passband than the K&L BR filters. Whenever I'm in my local surplus
junk store, I sort through their bins of unmarked microwave hardware. If
it's a two-terminal device and has TNC or N connectors, I'll offer them a
buck or two. Just characterize it in a 50 ohm system, and you can eventually
build up a handy library of filters.
Regards,
Ed
Ed Price
[email protected]
Electromagnetic Compatibility Lab
Cubic Defense Systems
San Diego, CA USA
858-505-2780 (Voice)
858-505-1583 (Fax)
Military & Avionics EMC Is Our Specialty
Shake-Bake-Shock - Metrology - Reliability Analysis
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