Radiometer

Details Radiometer Radiometer

1982-06-11

1985-07-02

Blum, Theodore M.

Communications: radio wave antennas

Antennas

Balanced doublet - centerfed

H04B 700

Patent

active

045271623

ABSTRACT:
A radiometer of the switched type has an R.F. switch connecting a detector selectively either to an antenna whose temperature (in terms of noise energy) is to be determined, or to a reference temperature, i.e. a resistive termination. The detector output is passed through an amplifier whose gain is switched between positive and negative values (for example +1 and -1) synchronously with the R.F. switch. The output of the switched gain amplifier is integrated to produce a rising voltage when the gain is positive and a falling one when it is negative. When it is positive the detector is connected to the antenna. By means of a zero crossing detector, a counter is started when this voltage crosses zero. After a fixed period, the R.F. switch and switched gain amplifier are reversed by the counter to cause the voltage to fall in accordance with the temperature of the resistive termination. The zero crossing detector and a counter measure the time interval until the voltage again crosses zero, such time interval being compared to the fixed period to provide a comparison of the unknown and reference temperatures independent of the gain of the detector, which is a valuable improvement over prior radiometers. Also, by measuring time rather than voltage, the arrangement facilitates providing a digital output more suitable for storage and transmission of the data than the analog output of prior radiometers. The instrument, which is relatively simple, rugged and compact, lends itself well to unattended use in monitoring the effect of rain storms on transmission in the 11.7 to 12.2 GHz band employed for satellite communication.

REFERENCES:
patent: 3017505 (1962-01-01), Clapp
patent: 3023361 (1962-02-01), Conner, Jr.
patent: 3129330 (1964-04-01), Seling
patent: 3325644 (1967-06-01), Frye et al.
patent: 3380055 (1968-04-01), Fow et al.
patent: 3493753 (1970-02-01), Stowe
patent: 3911435 (1975-10-01), Mardon et al.
patent: 4008398 (1977-02-01), Schramm et al.
patent: 4144527 (1979-03-01), Butler et al.
patent: 4317184 (1982-02-01), Leszczynski
patent: 4347515 (1982-08-01), Hoover, Jr.

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