Hello Ashish and welcome to the TM Forum,
This NA is obsolete. The detectors for use with this NA are the 11664A/B series. The link below is to the user manual. It lists all the measurement components used with this NA. I suggest downloading it (pdf) for future reference. Agilent has a habit of removing obsolete equipment documentation without notice.
http://cp.literature.agilent.com/litweb ... -90013.pdfGood Luck,
RFTEJerry