I would like to share with you the construction technique that I have experimented in building ultra-light antennas for portable use.
In this case, I build a 144-MHz 4 element Yagi-Uda 1 meter long that weights only 100g (3 1/2 oz) including elements, boom and connector.
A fiberglass fishing rod section is used as a boom and 2.3mm aluminum TIG soldering rods as elements.
The entire project is at this link: http://www2.iz2uuf.net/index.php/ham-radio/10-100g-yagi
I hope it could be of your interest and comments are welcome.
73 de IZ2UUF