Because the null mode can provide a very sharp bearing, readable to plus or minus 5 degrees. The Loop Antenna has the advantage of being less affected by reflection signals due to its Faraday sheild. By itself, the loop can provide the entire antenna.Requirement provided the signal is strong enough to be received by the untuned loop. If the signal is to weak, a Yagi is recommended for its directional gain. If the signal is too strong, the use of an attenuator may be required. ARDF is an art, not a science. You need practice to acquire that skill. The item "Arrow Antenna FHL-UHF Fox Hunt Loop 1MHz-1000MHz" is in sale since Friday, February 28, 2020. This item is in the category "Mobile Phones & Communication\Radio Communication Equipment\Antennas\Ham/Amateur Radio Antennas". The seller is "radiosuperstore" and is located in Woburn Sands, Milton Keynes. This item can be shipped to United Kingdom, Japan, Canada, Ireland, Australia, Germany, France, Greece, Italy, Spain, Antigua and barbuda, Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech republic, Denmark, Estonia, Finland, Hungary, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Sweden, Bahrain, Brazil, New Zealand, China, Israel, Hong Kong, Norway, Indonesia, Mexico, Singapore, South Korea, Switzerland, Taiwan, Thailand, Bangladesh, Belize, Bermuda, Bolivia, Barbados, Brunei darussalam, Cayman islands, Dominica, Ecuador, Egypt, Guernsey, Gibraltar, Guadeloupe, Grenada, French guiana, Iceland, Jersey, Jordan, Cambodia, Saint kitts and nevis, Saint lucia, Liechtenstein, Sri lanka, Macao, Monaco, Maldives, Montserrat, Martinique, Nicaragua, Oman, Pakistan, Peru, Paraguay, Reunion, Turks and caicos islands, Aruba, Saudi arabia, South africa, United arab emirates, Ukraine, Chile, Bahamas, Colombia, Costa rica, Dominican republic, Guatemala, Honduras, Jamaica, Kuwait, Panama, Philippines, Qatar, El salvador, Trinidad and tobago, Uruguay, Viet nam.