Your browser does not support JavaScript!
http://iet.metastore.ingenta.com
1887

Application of 3-port coaxial junction to r.f.-immittance standardisation and measurements

Application of 3-port coaxial junction to r.f.-immittance standardisation and measurements

For access to this article, please select a purchase option:

Buy article PDF
$19.95
(plus tax if applicable)
Buy Knowledge Pack
10 articles for $120.00
(plus taxes if applicable)

IET members benefit from discounts to all IET publications and free access to E&T Magazine. If you are an IET member, log in to your account and the discounts will automatically be applied.

Learn more about IET membership 

Recommend Title Publication to library

You must fill out fields marked with: *

Librarian details
Name:*
Email:*
Your details
Name:*
Email:*
Department:*
Why are you recommending this title?
Select reason:
 
 
 
 
 
Proceedings of the Institution of Electrical Engineers — Recommend this title to your library

Thank you

Your recommendation has been sent to your librarian.

The calibration of immittance bridges and reflection-coefficient meters over the complete radio-frequency spectrum requires a wide range of fixed standards of complex immittances or reflection coefficients. This can be accomplished with a relatively small number of fixed standards by connecting them in series or parallel and computing the value of the composite standard. The series connection is readily achieved by using precision coaxial connectors which form an integral part of the standards, and has already been described in a previous paper. Parallel connection, however, requires a multiport coaxial junction, the parameters of which enter into the immittance characteristic of the composite standard. The symmetrical 3-port coaxial junction is analysed, and it is found that the most convenient method of characterising it at the highest level of standardisation is in terms of scattering parameters normalised to its complex characteristic impedance. The low-frequency scattering matrix, comprising real numbers only, is evaluated in terms of d.c. concepts. It is then shown that the general matrix applicable at all frequencies is given by multiplying the d.c. matrix by e−2(α+jβ)1, where 1 is the length of each arm. Formulas are given for the input reflection coefficient of one arm of the junction in terms of the reflection coefficients of the fixed standards connected to the remaining two ports. Various techniques are discussed for evaluating the scattering parameters of the junction to an accuracy that would not significantly degrade the accuracy of the fixed standards, assumed to be in the order of 0.1%. The technique is considered to be equally as applicable to low frequencies as to microwave frequencies, thus enabling a unified computing program to be employed. Extension of the technique to cascaded 3-port junctions is also considered, whereby more than two fixed standards can be connected in parallel. For less-accurate standardising work, as performed by certain calibration laboratories, it is shown that adequate accuracy can be achieved by adopting a simpler procedure, whereby the scattering parameters of the junction and the reflection coefficients of the standards are all normalised to an ideal real characteristic resistance Rn.

http://iet.metastore.ingenta.com/content/journals/10.1049/piee.1972.0059
Loading

Related content

content/journals/10.1049/piee.1972.0059
pub_keyword,iet_inspecKeyword,pub_concept
6
6
Loading
This is a required field
Please enter a valid email address