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Veritech Inmarsat LNAs Suitable for SETI

The sensitivity of any SETI receiver is largely a function of its low noise receive preamplifier, or LNA. At regional VHF and UHF conferences every year, radio amateurs distinguish themselves by presenting ever quieter LNAs for a number of frequency bands, including some used for radioastronomy and SETI. Though amateur construction techniques have proven perfectly adequate for producing state-of-the-art LNAs over narrow bandwidths, consistent performance across wider bandwidths has often eluded us. Thus, some SETI League members are turning to commercial hardware vendors to achieve the bandwidth necessary for complete Water-Hole coverage.

One product which has come to our attention is an LNA developed for the International Maritime Satellite (Inmarsat) service. Veritech Microwave, Inc. of South Plainfield NJ produces a family of coplanar thin-film PHEMT preamplifiers offering uniform gain and noise temperature across the entire 1.4 to 1.8 GHz band. Small, well packaged, and with SMA connectors, these LNAs rival, across the entire Water-Hole, the kind of performance that amateurs typically achieve only at spot frequencies. One unit which appears especially suitable for SETI is their Model No. VMA 1.6C-126A. At 26 dB gain and 36 K noise temperature, this particular LNA can be used in front of an existing commercial receiver (see, for example, the ICOM 7000 Series) to easily achieve a 50 K overall system noise temperature. Of course, a suitable parabolic dish antenna and feedhorn will be required.

The Varitech preamps, developed as they were for a commercial satellite market, are not inexpensive. The SETI League received a quote of $1685 for the model cited above. There will certainly be more cost-effective solutions proposed in the months ahead, some of which are currently under development in our labs. But for those not willing to restrict their searches to the Hydrogen Line region alone, who are unwilling to wait for new designs, or who demand state-of-the-art performance at any cost, the Varitech LNAs appear to be worthy of consideration.

Further information can be received from:

Veritech Microwave, Inc.
111-B Corporate Boulevard
South Plainfield, NJ 07080
voice (908) 769-0300
fax (908) 769-0330

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