Guasti, Try; http://vnahelp.com/ Its a helpful website John =20 -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Guasti Giovanni Sent: Thursday, July 21, 2005 2:16 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] four S channels VNA dear all, our laboratory bought two hibrid junctions a long time ago. I am trying =3D to obtain a four S channels VNA, placing the hibrid junctions in series =3D to our two S channel VNA. I would like to realize some differential =3D scattering measurements (at the moment we couldn't buy = a new 4 channel =3D VNA).=3D20 How would you calibrate the whole system? = Do you know any article, =3D paper, web-site where I could read more about it? Do you think a =3D differential to common mode coupling could affect the measurement? I'm waiting for all your objections. ;-) Thankyou all, Giovanni HJ +90=3DB0 |------| HJ -90=3DB0 |-------| diff |-------| VNA S1-------< | DUT | >------- VNA S2 |-------| |-------| |------| HJ -90=3DB0 HJ +90=3DB0 =3D20 ^ ^ | | sect1 sect2 all cables have same length, all cables have Z0=3D3D50ohm Hibrid Junctions have a bandwidth B - so the measure will be done in B ----------------------------------------------------------- open (S2 is symmetrical) HJ +90=3DB0 =3D20 |-------High impedance VNA S1-------< =3D20 |-------High impedance =3D20 HJ -90=3DB0 =3D20 ----------------------------------------------------------- short (S2 is symmetrical) HJ +90=3DB0 =3D20 |-------0ohm VNA S1-------< =3D20 |-------0ohm =3D20 HJ -90=3DB0 =3D20 ----------------------------------------------------------- 50ohm (S2 is symmetrical) HJ +90=3DB0 =3D20 |-------50ohm VNA S1-------< =3D20 |-------50ohm =3D20 HJ -90=3DB0 =3D20 ----------------------------------------------------------- through HJ +90=3DB0 HJ -90=3DB0 |--------------| VNA S1-------< >------- VNA S2 |--------------| =3D20 HJ -90=3DB0 HJ +90=3DB0 =3D20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: =20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu