While the Pennant is easier to build, the Flag is symmetrical and therefor adaptable to a rotatable configuration.
http://www.hard-core-dx.com/nordicdx/antenna/loop/flag/flag_w7iuv.html
If you know your desired frequency, gain, length of boom etc, then you can determine other parameters from the supplied excel sheet. For example, the author has built a short 13 element Yagi using one meter long 15 x 15 mm square Aluminum boom, elements are 4 mm hard aluminum wire.
http://df2ck.de/tech/23cm_yagi/23cm_yagi.html
4 Element
http://www.qsl.net/n6bg/thunt/quad.html
The discone is a popular wideband antenna for VHF and UHF. This article shows you how to build a very efficient one for your UHF scanner.
http://krasnodar.online.ru/hamradio/ftp/discone.pdf
reception antennas which work close to earth.
http://www.hard-core-dx.com/nordicdx/antenna/special/swlant.html
Do you find it difficult to measure height of your antenna tower? No you do not have to climb along it with a measurement tape, Just build this low cost jig and measure height in 15 minutes.
http://www.webx.dk/oz2cpu/ant-height.htm
An easy step-by-step guide go making a homemade wireless antenna, for a fraction of the cost of commercial antenna.
http://wireless.gumph.org/articles/homemadeomni.html
This article is about the ability of an LC resonator to "funnel" incoming electromagnetic waves towards tiny antennas.
http://www.amasci.com/tesla/tesceive.html
CB antenna for every application like car mount, portable use etc. Several designs and tips & tricks.
http://home.att.net/~wizardoz/cbmw/antenna_fabri.html
Some practical methods.
http://www.hard-core-dx.com/nordicdx/antenna/loop/loop3.html