Text preview for : 1951-09.pdf part of Agilent 1951-09 Agilent journals 1951-09.pdf
Back to : 1951-09.pdf | Home
?^^ HEWLETT-PACKARD
(Kg) JOURNAL
f * T E C H N I C A L I N F O R M A T I O N F R O M T H E - h p - L A B O R A T O R I E S
VOL. 3 No. 1
'UBLISHED BY THE HEWLETT-PACKARD COMPANY, 395 PAGE MILL ROAD, PALO ALTO, CALIFORNIA SEPTEMBER, 1951
Good Practice in Slotted Line Measurements
A REVIEW of the literature will disclose characteristic of the various devices used in
A\. that much has been written on the sub slotted line work.
ject of proper techniques for making meas A generalized set-up for measurements
urements with slotted lines, but such infor with a slotted line section is shown in Fig. 1.
mation is generally interspersed among oth A signal source, usually a signal generator or
er information. With the increasing amount internal-cavity reflex klystron at UHF-SHF
of work going on at UHF and SHF frequen frequencies, feeds through a slotted section
to the load whose characteristics are to be
cies, many engineers find themselves with a
measured. The signal source is commonly
need for making slotted line measurements
for the first time. Others have only occasional amplitude-modulated in order to simplify
need for such measurement. In either case the design of the associated measuring equip
ment. The fields in the line are sampled by
the engineer must do considerable research
means of a probe which protrudes into the
to obtain a coherent overall picture of good
slotted section. The sampling probe may
practice and of the equipment available for
connect to a detector which in turn connects
the particular measurements to be made. As
to an indicating device such as a high-gain
a result of this situation, instances occur
audio voltmeter calibrated in standing- wave
rather frequently where erroneous results
are obtained because of oversight of some ratio; or the probe may connect directly to a
receiver in which case modulation of the sig
nal source can be omitted.
In this generalized set-up, some six differ
ent devices are employed and it is possible
that each of these devices will introduce ef
fects that contribute to errors. Fortunately,
it is possible to reduce most of these effects to
the point where they have negligible influ
ence. In fact, the substance of good practice
when making measurements with slotted
lines is insuring that these effects are made
negligible. The following discussion of good
practice pertains in general to measurements
made with either coaxial or waveguide slot
Fig. 1. Typical set-up for making slotted-line measure ted lines; special mention is made when only
ments using sqitare-icave-modiilated signal generator,
slotted section, and standing-wave indicator. one type of system is involved.
P R I N T E D I N U . S . A . C O P Y R I G H T 1 9 5 1 H E W L E T T - P A C K A R D C O .