2

I need a series component to isolate a 2440MHZ antenna for testing purposes-- it can either be a a high quality 0402 RF capacitor (Johansen) or a zero ohm resistor.

The series component will remain on after the product is shipped.

I do have any experience with zero ohm jumpers at RF but I have used 8-10pf high quality RF capacitors in the 0402 to make a short..the impedance of this device must be quite negligible on paper when connected to a 50 resistive load.

If I want minimum variation in the product due to the jumper, should I use a zero ohm jumper or high quality capacitor?

BHS
  • 145
  • 7
  • 1
    It is not clear why you need this instead of a plastic film battery insulator or a removable antenna switch with 0dB Return loss. The physical contraints must be defined. – Tony Stewart EE75 Jan 02 '20 at 19:51
  • 1
    The part is to make a connection between 3 different nodes. Node 1 is the transmitter. Node 2 is a UFL connector for VNA or spectrum analyzer. Node 3 is the feed to transmission line which is connected to a matching network which is connected to an antenna. – BHS Feb 03 '20 at 22:14
  • 1
    My gut says use an RF cap. Hiring a real RF engineer for 1 or 2 hours to answer the question after reviewing all the relevant material would probably be a worthwhile expense. The specs for zero ohm jumpers are not very forthcoming about a lot of things. Even the DC resistance is only specified to be less than 10 mOhms. For some higher current applications, that is much too high and you would be forced to use a metal wire or a low-ohm resistor to insure you do not get excessive power loss. – user57037 Feb 04 '20 at 00:11
  • 1
    We decided to use an RF cap rather then measure 100 or so jumpers from different manufacturers with a VNA – BHS Feb 27 '20 at 22:48

1 Answers1

-1

Not knowing what your metric of goodness is (loss?), it's hard to say. What I would do is to model both in a 3-D E&M simulation tool like HFSS, embed that model into your circuit, extract the relevant S-parameters, and see where you stand.

SteveSh
  • 9,672
  • 2
  • 14
  • 31
  • The relevant metric is manufacturing variation in the magnitude of impedance in zero ohm jumper versus high quality capacitor. – BHS Feb 03 '20 at 22:14