IW is pleased to announce that it has developed a new line of coaxial cables and assemblies which has improved the performance characteristics for all types of microwave applications. This new line of cable and assemblies yields smaller diameters, lighter weights, lower insertion loss, and enhanced electrical stability versus temperature and flexure. This adds up to the "Best of all worlds" for an engineer designing high performance systems.

Low Loss, Phase Stable Cable
In it's continuing effort to supply the microwave industry with the highest possible performance, Insulated Wire, Inc., is pleased to announce that it has developed a new line of coaxial cables and assemblies, which has improved the performance characteristics for all type of microwave applications. This new line of cable and assemblies yields smaller diameters, lighter weights, lower insertion loss and enhanced electrical stability versus flexure and temperature. This all adds up to the "Best of all Worlds" for an engineer designing high performance systems. We believe it is imperative that our customer gets the maximum performance, from the widest possible range of products, delivered on time, for the lowest cost.

This new cable line incorporates significant design changes resulting in improved performance. These cables meet or exceed all the material requirements outlined in the MIL-C-17 specification and utilizes silver plated copper conductors, with a very low loss, expanded PTFE dielectric. The outer conductor consists of pure silver, applied in a new proprietary manner that yields lower contact resistance, thus decreasing insertion loss. This new cable line also incorporates a secondary, silver plated, copper braided shield that contributes to excellent RF leakage characteristics, specified at > -100 dB to 18 GHz. The standard outside jacket is a tough, resin melt, extruded FEP, however, PFA, Polyurethane, Tefzel™ and PEEK can be used, depending on the application requirements. IW will also offer an internal ruggedization for cable assemblies, or external armor to provide further mechanical or environmental protection. The internal ruggedization offers enhanced crush resistance and a tighter bend radius. This design offers a more compact package than does the external armor, keeping the size and the weight of the cable assembly down. These assemblies include tough, stainless steel connector bodies. The patented connector designs yield proven performance in the field, on programs, such as, Phalanx, HDR, Cobra Gemini and 767 AWACS.

he 1801 series cable measures .180" in diameter and typically measures 0.33 dB per foot, at 18 GHz. This is a vast improvement when compared to other available cables on the market, as well as, IW's previous cable, which measured 0.37 dB per foot, at 18 GHz and measured .230" in particularly well suited to airborne and satellite applications. The lower insertion loss over long runs of cable allows for less power to be applied, which has the potential to eliminate expensive amplification systems. This new design also yields improved VSWR performance. The typical 1801, (4) four-foot long cable assembly with SMA connectors has a 1.20:1 VSWR to 18 GHz; the 1501 series cable assembly of the same length with 2.9mm connectors has a typical VSWR of 1.25:1 or better to 40 GHz.

The 1401 operating to 50 GHz and the 1501 to 40 GHz make excellent test cables. The very low VSWR and overall electrical stability when flexed, make this cable assembly an inexpensive alternative to the expensive ANA cables. These cables can be ruggedized to withstand production test environments as well as, harsh thermal environments from -65 to +200 degrees Celsius. These cables will withstand repeated flexure and remain within very tight electrical specifications. The 1501 cable data shown for phase stability versus flexure indicate less than a 5 degree change in electrical length at 40 GHz, when the cable is flexed into a tight, 3" diameter coil. The insertion loss or amplitude stability is also excellent at < 0. 1 dB through 40 GHz.

The excellent stability and high power handling capability makes these cables very good choices for phased array antenna systems. It is extremely important that interconnection cables remain electrically stable during the installation of these sensitive systems. When necessary, IW will phase match assemblies to system requirements. The new cable design allows multiple bends to be put into these matched cables, without significant changes to the electrical length, in addition, this design is very amplitude stable. These cable assemblies typically change < 0.1 dB, at their maximum frequency with the cable bent to the minimum bend radius. The cables are all very flexible and can endure thousands of flexures and remain within the stated electrical specifications set forth.

The low loss nature of these cables allows for higher power levels to be used. This cable technology is being used to help save lives within the field of cardiac medicine. IW is currently supplying a cable used in a microwave ablasion catheter, used to address cardiac rhythm irregularities. The system uses microwave energy to destroy tissue buildup that can cause electrical disturbances and cardiac arrhythmia. IW was selected for this important system because it could offer the smallest diameter cable and worked with the engineers and doctors directly in the development of this cable to achieve the lowest loss, to allow for the greatest amount of power to be applied and keep the catheter within normal body temperatures. As with any of it's customers, IW goes the "extra mile" to help make a system work properly.

This line of cables is also extremely phase stable when exposed to changes in temperature. It is critical that matched cables change electrically within as small a tolerance window as possible and track in a similar fashion from one cable to the next to maintain proper overall system performance. The change in electrical length must be predictable and consistent. Shown in the graph is a comparison to semi-rigid cable that reflects the improvement that this new design shows over those cable assemblies utilizing solid, PTFE dielectric. The expanded PTFE dielectric material has a nominal velocity of propagation of 84%, making it less reactive to thermal changes when compared to solid PTFE core. The phase profile for this design is very flat and within 600 PPM over a -50 to +120 degree Celsius. This puts this cable among the most phase stable assemblies available from any manufacturer.

The whole line of cables, gives the user great overall flexibility when designing systems. The part number corresponds to the diameter of the cable; an example is the 2401 is actually .240". These are standard sizes, but IW can manufacture a wide variety of coax cables using this new design to specific customer requirements. IW also offers cables with a 75-ohm impedance that utilizes this new design technique in varied diameters depending on insertion loss requirements.

IW manufactures the broadest line of coaxial cable assemblies available from any company in the microwave industry. Our Microwave Products Division will work closely with its customers, to provide "On-Site" assistance, supporting the successful completion of any interconnection project. IW offers custom, multiconductor cable and assemblies for use, in a wide variety of applications. A complete range of wire and cable products are available including low cost, high performance alternatives to RG cable types. These on-going efforts make IW the industry leader in microwave interconnection technology.

IW supplies internal ruggedization, designated by replacing the '1' in the part number with a '3'. This internal ruggedization is available only on cable assemblies. Example: 1801 becomes 1803

Reproduced from the Microwave Product Digest

Phase Change With Flexing: Phase change when flexing will be slightly different depending on the particular cable. Larger cables have more dieletric and greater internal forces, thus the phase change of larger cables will be greater than smaller diameter cables. When wrapped 360° around a 4 inch cable diameter mandrel, the phase change will be:

Cables 4806, 2301, and 1801: Phase change = ± 0.30*F.
Cables 1501 and 1401: Phase change =± 0.15*F.
F is the frequency in GHz and phase change is in degrees