If you don't want to spend big on aluminium tubing, or have no defunct TV antennas handy, an alternative material for yagi antenna elements are old metal tape measures. Beams can be made super light weight and the element springiness makes them easy to pack.
This makes them ideal for fox hunt or ARDF hand-held sniffers. Other applications include range boosters for handheld transceivers, contest beams for VHF/UHF field days and use for satellite communication. They also make a great educational project to demonstrate antenna concepts like gain and front to back ratio for an amateur licence study class.
Follow the links below for ideas and inspiration:
KB9VBR tape measure yagi for 2m foxhunting
KB9VBR tape measure yagi for 2m foxhunting (video)
WB2HOL tape measure yagi optimised for 2m direction finding
ZL2APS tape measure yagi for 70cm
Testing a 2m tape measure yagi One of my videos testing reception of a satellite
The main disadvantage of tape measure yagis (especially those on 2m) is that in moderate to high winds their elements flex. This reduces their gain and directivity, and, when it's really blowing, makes them useless. You may be able to reduce this by fitting some sort of line or string across the elements for bracing.
This makes them ideal for fox hunt or ARDF hand-held sniffers. Other applications include range boosters for handheld transceivers, contest beams for VHF/UHF field days and use for satellite communication. They also make a great educational project to demonstrate antenna concepts like gain and front to back ratio for an amateur licence study class.
Follow the links below for ideas and inspiration:
KB9VBR tape measure yagi for 2m foxhunting
KB9VBR tape measure yagi for 2m foxhunting (video)
WB2HOL tape measure yagi optimised for 2m direction finding
ZL2APS tape measure yagi for 70cm
Testing a 2m tape measure yagi One of my videos testing reception of a satellite
The main disadvantage of tape measure yagis (especially those on 2m) is that in moderate to high winds their elements flex. This reduces their gain and directivity, and, when it's really blowing, makes them useless. You may be able to reduce this by fitting some sort of line or string across the elements for bracing.
PS: Many other portable antennas are covered in Hand-carried QRP Antennas. Available in electronic and paperback form (some countries) this well-reviewed book is a popular read amongst hams who go portable.
Something the metal tape has got me wondering about is using them for a portable J-Pole antenna -- and with a squid pole, they could be hoisted enough meters above the ground.
ReplyDeleteI've build the (heavy copper..) 'bushwalkers' J-Pole for 2m from AR Aug 2005, however metal tape w/ squid makes a 6m j-pole antenna look doable...
Chris - it sounds very doable. Especially if you made up plastic spacers from chopping board to hold the tape to the squid pole, separated by a couple of cm.
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