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MICROWAVE PRODUCT DIGEST

SM08790-47/47L Microwave Product Digest

As cellular systems are being upgraded to provide digital service, many providers are finding that conventional base stations do not always provide satisfactory service over the entire cell. This is typically caused by two issues: first is coverage holes, which are caused by obstructions like those found in urban areas and indoor locations; second is dropped calls, due to over-capacity.

To effectively address these issues, providers are selecting smaller, less expensive repeater stations, which simultaneously fill coverage holes and increase capacity. However, as wireless communications increase in popularity, more powerful repeaters are needed to help cellular systems maintain quality service.

One of the main challenges repeater manufacturers face, as they try to increase their output power, is the performance of the power amplifier. Requirements for these units include high RF power, very low DC power consumption, small size and an affordable price.

Stealth Microwave has established itself as a leading manufacturer of compact, high quality, ultra-linear amplifiers. Their latest model, SM08790-47, offers an improved solution to higher power repeater requirements. Using the latest LDMOS technology, the SM08790-47 can provide 41 dBm of CDMA performance while consuming only 3.5 Amps @ 24 VDC.

If higher linearity is required, the SM08790-47L can produce 41 dBm of average output power, with 4 CDMA signals, while meeting IS-95A requirements. Power consumption is 5.1 Amps @ 24 VDC. The multi-carrier performance is achieved through Stealth’s proprietary linearization, which corrects the non-linearities of the amplifier with amplitude and phase compensation.

Both units operate over the entire cellular band, provide 51 dB of linear gain. Gain flatness is ± 0.4 dB, and the input/output VSWRs are 1.6:1.

The amplifiers have several built in features including single supply operation (+24V), over/reverse voltage protection, and thermal shutdown (with automatic reset). Logic On/Off control, which is also standard, allows the end user to turn the unit on or off with a TTL signal. The SM08790-47 also provides over 30 dB of linear gain attenuation. Optional Forward/Reverse Power detectors are also available which monitor the transmitted and reflected power. All of the aforementioned is available over a temperature range from 0 to +75° C (baseplate).

The unit comes with 4 thru-holes and measures 6.5"L x 3.7"W x 1.0"H. An optional heatsink is also available.