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SILICON CHIP PUBLISHER'S LE'I-IER Publisher & Editor-In-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Regular Contributors Neville Williams, FIREE, VK2XV Bryan Maher, M.E. B.Sc. Jim Yalden, VK2YGY Garry Cratt, VK2YBX Jim Lawler, MTETIA Photography Bob Donaldson Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 1 2 times a year by Silicon Chip Publications Pty Ltd . All material copyright (c). No part of the contents of this publication may be reproduced without prior written consent of ttie publisher. Kitset suppliers may not photostat articles without written permission of the publisher. Typesetting/makeup: Magazine Printers Pty Ltd, Waterloo , NSW 2017 . Printing: Macquarie Publications Pty Ltd, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscription rates are currently $42 per year ( 1 2 issues). Outside Australia the cost is $62 per year surface mail or $120 per year air mail. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Address all mail to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy B.,each , NSW 2097 . Phone (02) 982 3935 . ISSN 1030-2662 * Recommended and maximum Australian price only . 2 SILICON CHIP There's a UHF antenna in your future Some time ago we planned to publish a four-bay bow-tie UHF antenna. We thought it would be quite a popular project since more and more viewers, even in the country, are now being serviced with UHF television broadcasts. The bow-tie array we are publishing this month has a number of desirable advantages over the more familiar long Yagis used for UHF. First, it covers both UHF bands and it has better discrimination against "aircraft flutter". With those thoughts in mind, we were quite pleased to be going to press with this antenna as featured in our article. And that would probably have been the end of the story as far as our January issue was concerned. However, just as we were going to press, the Department of Transport and Communications issued stage one of a timetable for television channel changes from the VHF to the UHF bands. This is the long awaited announcement of the Department's plan to move television stations from the FM band, so that more FM stations can go on the air. Most of the displaced TV stations will have to move to the UHF (ultra high frequency) bands. The timetable will mean far reaching changes for millions of people around Australia. Whereas most people up till now have not felt a pressing need to install a UHF antenna, even though some UHF services have been available, they will now have to do so. It will be mandatory, if they wish to continue watching the same programs. Three television channels are in the FM band, 88 to 108MHz: channels 3, 4 and 5. As well, channel 5A will also be moved upwards. And a number of translator services occupying channels elsewhere in the VHF (very high frequency) bands will also move into the UHF bands to make way for some of the stations moved from the FM bands. In stage one of the timetable just released, 15 TV stations and three translators will be moved from channels 3, 4, 5 and 5A. These moves will be accomplished by late 1990. Stage 2, for channel changes after 1990, will be announced in the next few months. We'll publish full details of the changes as they become available. The changes have been decided upon after a long period of consultation with all parties in the TV broadcast industry. In the short term, they will cause some disruption while viewers slowly make the necessary adaptations. In the long run, we'll have a lot more FM stations which will be all to the good. But sooner or later, many more people will be watching UHF TV broadcasts. Which makes our UHF bow-tie array rather timely, doesn't it? Leo Simpson