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I'm wondering if a HP8756A network analyzer by itself is enough to measure the resonant frequency of a GPS chip antenna?

The reason I am concerned that it cannot is because I cannot see a "RF Out" connector on the front panel. I hired a portable NWA last time I wanted to measure the resonant frequency, and it had a "RF Out" connector on it. Does the HP8756A require an external "sweeper" (more costly hardware) to generate the RF signal?

An example of a HP8756A is http://www.ebay.com/itm/Agilent-HP-8757A-10-MHz-100-GHz-Scalar-Network-Analyzer-/131016149080?pt=LH_DefaultDomain_0&hash=item1e812bc858

The manual for the HP8756A can be found at http://www.teknetelectronics.com/ManualsPDF/HP_AGILENT/HP__8757A_OM_1.pdf

For an example of a NWA with a "RF Out", see the HP 8753C at http://www.ebay.com/itm/HP-8753C-Network-Analyzer-300-kHz-6-GHz/281062308784?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D777000%26algo%3DABA.MBE%26ao%3D1%26asc%3D27538%26meid%3Dbc1bc0d4ce4b49a5a1333d41ff4fbc54%26pid%3D100009%26prg%3D11353%26rk%3D1%26rkt%3D4%26

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Yes, you will need an external RF source of some sort (ideally a sweeper) and a directional detector (e.g. http://www.ebay.com/itm/HP-Agilent-85021C-Directional-Bridge-10MHz-18GHz-/301374539011) or directional coupler and detector (e.g. http://www.ebay.com/itm/HP-11664A-18Ghz-Detector-for-HP-8756-HP-8757-/380853230821). These units have no RF electronics in them at all; they are basically glorified power meters - you need to supply the source and the detectors. I have not used one of these myself, but I think the way it's intended to be used is you put a splitter on the source so part of the signal is sent to a detector for the R (reference) port, then you can put a directional coupler and another detector between the other port on the splitter and your DUT port to measure the reflected power. Other detectors can then be used for transmitted power out of other DUT ports.

Some of the older VNAs need an external source as well, but it gets sent in through the back of the test set instead of the front.

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  • \$\begingroup\$ Thanks, o.k., might look into an all-in-one device. Do you know of any common, cheapish NWA models that have a built in RF generator? \$\endgroup\$
    – gbmhunter
    Nov 4, 2014 at 4:39
  • \$\begingroup\$ Define 'cheapish'. I would suggest a used 8753, those can be had for 'relatively' cheap. This is another possibility: sdr-kits.net/VNWA3_Description.html . \$\endgroup\$
    – alex.forencich
    Nov 4, 2014 at 6:37
  • \$\begingroup\$ Up to say US$3000? Yes I looked at the VNWA3, but unfortunately it stops at 1.3GHz, and I need something that can do both 1.5GHz (for GPS) and 2.4GHz (for WiFi/ZigBee). A used 8753 does look promising... \$\endgroup\$
    – gbmhunter
    Nov 4, 2014 at 20:19
  • \$\begingroup\$ That's probably your best bet. If you get one with option 006 with the correct test set, then it will go up to 6 GHz. Try searching on ebay for "network analyzer -scalar" and then set the max price to weed out the $20k behemoths. \$\endgroup\$
    – alex.forencich
    Nov 4, 2014 at 20:36

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