‰ NOW 40 WPM ‰ TEXT IS FROM DECEMBER 2005 QST PAGES 40, 41 AND 96 ‰ THROUGH THE NIGHT AND UP UNTIL ABOUT AN HOUR AFTER SUNRISE. AFTER SUNRISE, 80 METERS STARTS TO SUFFER ABSORPTION IN THE D LAYER OF THE IONOSPHERE AND HENCE THE SIGNAL STRENGTH DROPS. HERE, 80 METERS IS A TRUE NIGHTTIME BAND. LETS SEE WHAT HAPPENS FROM SAN FRANCISCO ‰ FROM PAGE 96 ‰ 2 52 5,474 WWA Smoky Mt ARC W4OLB N4VPQ 1587 2 54 5,326 TN Southwest FIGURE 2. THE 8 FOOT HEIGHT PUTS THE ENDS HIGH ENOUGH TO PREVENT RF BURNS TO HUMANS OR MOST ANIMALS. I GENERATED FIGURE 1 USING THE VOAAREA PROGRAM, PART OF THE VOACAP PROPAGATION PREDICTION SUITE, FOR THE MONTH OF DECEMBER. THIS WAS FOR 0000 UTC, CLOSE TO SUNDOWN, FOR A LOW PERIOD OF SOLAR ACTIVITY SMOOTHED SUNSPOT NUMBER, SSN OF 20. THE RECEIVING STATIONS WERE ALSO ASSUMED TO BE USING IDENTICAL INVERTED V DIPOLES. YOU CAN SEE THAT ALMOST THE WHOLE STATE OF CALIFORNIA IS COVERED WITH S9 SIGNALS, MINUS ONLY A THIN SLICE OF LAND NEAR THE MEXICO BORDER IN THE SOUTHEAST PORTION OF THE STATE, WHERE THE SIGNAL DROPS TO S7. SIGNALS FROM TEXAS ARE PREDICTED TO BE ONLY S5 OR LESS IN STRENGTH. SIGNALS OR THUNDERSTORM STATIC COMING FROM, SAY, LOUISIANA WOULD BE SEVERAL S UNITS WEAKER THAN SIGNALS FROM CENTRAL TEXAS. NOW TAKE A LOOK AT FIGURE 1B. HERE, THE DATE, TIME AND SOLAR CONDITIONS REMAIN THE SAME, BUT NOW THE ANTENNAS ARE 100 FOOT HIGH FLATTOP DIPOLES. CALIFORNIA IS STILL BLANKETED WITH S9 SIGNALS, SAVE FOR AN INTERESTING CRESCENT SHAPED SLICE NEAR LOS ANGELES, WHERE THE SIGNAL DROPS DOWN TO S7. CLOSE INVESTIGATION OF THIS INTRIGUING DROP IN SIGNAL STRENGTH REVEALS THAT ‰ FROM PAGE 96 ‰ Amateur Radio Assn K6SOA K6WO 1871 2 64 7,044 ORG Brightleaf ARC W4AMC NC4PC 1798 2 25 7,006 NC Western Washington DX Club W7DX 2053 2 18 6,904 WWA North Shore Radio Assn NS1RA 1793 2 58 6,768 EMA Orange Co ARC W6ZE ‰ QST DE W1AW ƒ THE NECESSARY ELEVATION ANGLE, 44, FROM SAN FRANCISCO TO THIS PART OF SOUTHERN CALIFORNIA FALLS IN THE FIRST NULL OF THE 100 FOOT HIGH ANTENNAS LEVATION PATTERN. SEE FIGURE 3, WHICH SHOWS THE ELEVATION PATTERNS FOR FIVE 40 METER ANTENNAS AT DIFFERENT HEIGHTS. IN THE NULL AT A 44 TAKEOFF ANGLE, THE 100 FOOT HIGH DIPOLE IS JUST ABOUT EQUAL TO A 2 FOOT HIGH DIPOLE. ILL DISCUSS 2 FOOT HIGH DIPOLES IN MORE DETAIL LATER. FOR MOST OF CALIFORNIA, THE PROBLEM WITH 100 FOOT HIGH 40 METER ANTENNAS IS THAT INTERFERING SIGNALS FROM TEXAS, COLORADO OR WASHINGTON STATE WILL ALSO BE S9 IN SAN FRANCISCO. SO WILL STATIC CRASHES COMING FROM THUNDERSTORMS ALL OVER THE WEST AND MUCH OF THE GULF COAST. ED FARMER, AA6ZM, JOKINGLY TOLD ME THAT THE ARMY DOESNT HAVE ANY PROBLEM WITH INTERFERING SIGNALS THEY JUST CALL IN AN AIRSTRIKE. WE HAMS DONT GENERALLY HAVE THIS ABILITY, ALTHOUGH WE OCCASIONALLY CALL IN THE FCC. SEE FIGURE 4, WHICH SHOWS A TYPICAL DISTRIBUTION OF THUNDERSTORMS ACROSS THE US IN THE LATE AFTERNOON, ‰ FROM PAGE 96 ‰ N8WP 1938 2 38 6,742 ORG OH KY IN ARS K8SCH 1747 2 23 6,336 OH St Paul Radio Club and W0MR Radio Club WOMR K0AGF 1852 2 90 6,306 MN Sturdy ‰ END OF 40 WPM TEXT ‰ QST DE W1AW ƒ