High-power attenuators are often used to decrease the power level from a base station or communications tower when making measurements with a spectrum analyzer or portable communications instrument. Test instruments are usually only rated for input power levels approaching 1 W (+30 dBm) at most, and power levels from wireless communications transmitters can easily exceed 100 W. Unfortunately, the attenuation value of a high-frequency fixed attenuator changes at higher-power levels as the component's case temperature rises, leading to inaccurate power measurements or, in extreme cases, overloading and damage to the measurement equipment. To prevent the likelihood of such damage, the engineers at MECA Electronics (Denville, NJ) have assembled the MFK-PMK-1 Power Measurement Kit to replace high-power attenuators as a means of reducing signal levels into in-field measurement equipment when making power measurements.
The MFK-PMK-1 Power Measurement Kit (see figure) provides a useful combination of passive components for making in-field power measurements from 800 MHz through 2.2 GHz. The kit contains a MECA 715-30-1.500 V Type N directional coupler, one each 6-, 10-, and 20-dB fixed Type N attenuators from the MECA 605-dB-1 family, one MECA 490-1 Type N high-power termination, and a carrying case with foam insert for safe transit.
The key component in the kit is a model 715-30-1.500 V directional coupler. It is a 30-dB unit with ±1.75 dB coupling variations and 0.1 dB maximum insertion loss from 0.8 to 2.2 GHz. It has 27 dB minimum directivity with 1.15:1 maximum VSWR and handles 100 W average forward power and 10 kW peak power.
To optimize signal levels to the in-field measurement equipment, the MFK-PMK-1 Power Measurement Kit also contains several fixed attenuators. These MECA 605-dB-1 series attenuators have values of 6, 10, and 20 dB with 2-W average power and 250-W peak rating. They exhibit maximum VSWR of 1.20 :1 from DC to 6 GHz. The attenuation tolerance for the 6-dB model is ±0.30 dB and ±0.50 dB for the 10- and 20-dB models.
To handle high power, the kit contains a model 490-1 Type N termination. It is rated for 100 W average power and 5 kW peak power from DC to 4 GHz. It exhibits VSWR of 1.10:1 from DC to 1 GHz, 1.20:1 from 1 to 2.4 GHz, and 1.30:1 to 4 GHz.
The firm offers an Attenuator Load Kit for field measurements. It contains two each of MECA 603-dB-1 series 5-W Type N fixed attenuators in 3-, 6-, 10-, and 20-dB values. It also includes two each of MECA 630-dB-1F4 30-W Type N fixed attenuators in 3-, 6-, 10-, and 20-dB values, one MECA 405-1 5-W Type N load, one MECA 404-1 35-W Type N load, and a CD-ROM with technical notes. MECA Electronics, Inc., 459 East Main St., Denville, NJ 07834; (973) 625-0661, FAX: (973) 625-9277, e-mail: sales@e-MECA.com, Internet: www.e-MECA.com.