TABLE OF CONTENTS Four primary types of cables are used for RF signals: flexible, conformable, semirigid, and semiflexible [1, 2]. The most common electrical performance parameters to consider when choosing cables are insertion loss, VSWR, crosstalk (leakage), and maximum frequency of use. Mechanically, the primary consideration is to ensure that the cable provides the ability to conform to any tight bends that may be needed in routing of the cables. If sharp bends are encountered, the user should attempt to remedy this by using large, gentle looping of the cable because sharp bends cause signal degradation. Strain relief, such as cable sheathing and fastening, should be used.
Flexible cables are the most commonly used cable type for connecting a load board mounted connector to the tester. Because they are flexible, they are especially good for applications that require many cables to be connected. It is important to have a minimum bend radius of less than 0.5 inch typically the cable will have a diameter of less than 0.115 inch. When using in proximity to a handler or moving parts on the test head (i.e., docking hardware), excess exposed cable should be tied down to the load board.
Conformable-type cables are hand formable, but stiffer than flexible cable and can be preformed to retain a shape. They typically have better electrical performance and lower insertion loss than does flexible cable. Because of their stiffness, it is more difficult to force multiple cables to fit into a small space.
