. QST . m. range. weakly by troposphere propagation, but washeard when aurora was present coming fromthe north with the characteristic growling auroralQSB. On a different frequency assignment Mc, permission was obtained to install atransmitter five miles away sending pulses 150times per second, each being about 100 micro-seconds in duration. The transmitting antennawas originally a horizontal dipole to send radia-tion in all directions in the meridian plane. Arotary 4-element Yagi was then used for receiving,using a low-noise crystal-controlled converter anda Super-Pro receiver. The
. QST . m. range. weakly by troposphere propagation, but washeard when aurora was present coming fromthe north with the characteristic growling auroralQSB. On a different frequency assignment Mc, permission was obtained to install atransmitter five miles away sending pulses 150times per second, each being about 100 micro-seconds in duration. The transmitting antennawas originally a horizontal dipole to send radia-tion in all directions in the meridian plane. Arotary 4-element Yagi was then used for receiving,using a low-noise crystal-controlled converter anda Super-Pro receiver. The detector outputwas fed into an oscilloscope, the strong directsignal coming from the transmitter being usedto initiate each sweep. With the antenna pointingnorth during aurora and with the coming in by auroral propagation, weakecho pulses could be obtained, and the rangeeasily estimated. (See Fig. 6.) CENTERS OF AURORAL ECHOES AURORAL ZONE GEOMAGNETIC NORTH TRUE\NORTHAT\COLLEGE. 900 KM. DELTA 600KM. o NORTHWAY Fig. 7— Each point representsmaximum auroral activity at adifferent time. Azimuth determi-nations were usually made usinga transmitter equipped witha turnstile omnidirectional an-tenna, with a directive array onthe receiver. A hill impeded obser-vations to the northwest. ^ TRUE \ f GEOMAGNETIC NORTH \ •/ NORTH • 0° 330°, r^ • y^*^ / ^^\^ y^ • \>^1_^ L \30° 300/ \^ \ * • / >- >;/ \x • /\ >^ \ / tC • y^\* * \ / K\ \ \ /* /■ % \ ■ \ 27? ~~-— __/____^ J^^^ %■ > Variation of Ronge ond Azimuth l06Mq/sec. Rador Echoes from , !953 COLLEGE, ALASKA Aurora Fig. 8 — Results using high-powered search radar on 106 Mc.(Courtesy of K. Bowles) 14 QST for Fig. 9 — Auroral radar echoesdo not occur at short distances. RANGE PROBABILITIES OF Mc. 0 300 600 900 Ronge (km) From College, Alosko It has been shown by parallactic photograph}^that most visible auroral light comes from a
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
