Edmond J. Violette, Richard H. Espeland, and Kenneth C. Allen

Abstract: A diagnostic probe used to fully describe the propagation characteristics of a millimeter wave channel by nearly simultaneous recording of an impulse response, frequency spectra, amplitude response, and bit error rate is discussed. A 30.3 GHz carrier accommodates the subcarriers and baseband modulation modes in a fully coherent network. Signal–to–noise determining components will permit BER performance of better than 10-8 at a 500 Mb/s rate with a 25 dB fade margin through a clear air 50 km distortion free path. Back to back operation of the terminals and a short atmospheric path is used to establish the reference performance level of the hardware. Controlled multipath tests are reported to demonstrate probe capabilities and to obtain reference data to better classify the fades and resulting distortion which occur on terrestrial links at millimeter wavelengths. With dual reflectors, multipath data sets were compiled to aid in predicting bit error rate performance resulting from a combination of signal–to–noise ratio change and intersymbol interference. Included with the above data are corresponding measurements of the impulse response and amplitude distortion on the channel. Two additional coherent cw channels, 11.4, 28.8, and a Soon to be added 96.1 GHz channel, are included with the 30.3 GHz probe to aid in analyzing selective fades which fall outside the bandpass and to evaluate frequency dependent properties of a link.

Keywords: millimeter waves; propagation; digital; diagnostic; probe; wide-band

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