Impedance tuners are unique but vital tools that can provide invaluable insight into the behavior of active component designs, such as amplifiers, as well as passive circuits, such as antennas. Precision impedance tuners are based on sliding mechanical probes, with the impedance shown to a component or device under test determined by the position of the sliding probes. While such impedance tuners can represent a major capital investment for many RF/microwave laboratories, Focus Microwaves (www.focus-microwaves.com) has developed a cost-effective and compact impedance tuner, the model iMPT-LITE-1208, which is ideally suited for evaluating the performance of active and passive components for many wireless applications, including Bluetooth, cellular, and WiMAX designs. The iMPT-LITE-1208 operates at fundamental and harmonic frequencies from 0.8 though 12.0 GHz.
The model iMPT-LITE-1208 multipurpose tuner (see figure) weighs only 25 lbs for flexible placement anywhere in an engineering facility. It is a compact solution for making VSWR and harmonic measurements through 12 GHz. The iMPT-LITE-1208 employs two independent wideband RF probes and can tune to high VSWRsas high as 100.0:1 at fundamental frequencies and, with the two probes, can tune to two independent or harmonic frequencies. The iMPT-LITE-1208 provides VSWRs from 10.0:1 to 100.0:1 at harmonic frequencies. The easy- to-manage tuner is designed to work with other analysis instruments, such as a microwave vector network analyzer (VNA) or a radio test set, to evaluate the behavior of different components and devices at a range of impedance mismatches.
The iMPT-LITE-1208 is 40 to 60 percent the size and weight of the firm's classic three-probe MPT multipurpose tuner models. Its small size and weight make it ideal for "impermanent" installations, where it must be moved from one test bench to another, as well as with on-wafer probing equipment, to evaluate the performance of active devices and integrated circuits (ICs) while in developmental and/or still on wafer.
The iMPT-LITE-1208 is machined and assembled for minimal insertion loss, at 0.3 dB, and achieves outstanding repeatability in its impedance setting. The minimum repeatability is specified at -40 dB while typical repeatability is -50 dB. The probes move along a machined carriage mechanism capable of 25.4-micron steps, with the probes themselves moving in 1.5-micron steps. The small steps translate into 0.05-deg. phase resolution at 0.8 GHz and 0.75-deg. resolution at 12 GHz.
The compact impedance tuner measures only 15.5 x 8.044 x 6.390 in. (393.70 x 204.32 x 162.31 mm). The standard unit is supplied with 7-mm (APC-7) coaxial connectors. It is also available (as model iMPT-LITE- 1208N) with Type N connectors. The 7-mm-connector version is rated for power-handling capability of 30 W CW, while the robust Type N version is rated for power-handling capability of as much as 90 W CW. Focus Microwaves, 1603 St. Regis, Dollard-des-Ormeaux, Quebec, Canada H9B 3H7; (514) 684- 4554; Fax: (514) 684-8581; Internet: www.focus.com.