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Posted on April 1, 2006 by Jed Tumlinson | Posted under Shopping and Product Reviews
Marine Radio Direction Finder Antenna System
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Since then there have been a variety of different versions and style that have come to market and is used around the world. More than 400 of these systems are o9perated by US Federal Aviation and are found throughout airports in the United States. And they are just as widely used on the water. The DF antennas came about as a result of the needs of a variety of customers. Quasi Doppler Antennas cover UHF and VHF air band and marine band frequencies. DF antennas were designed for the VHF air band and could be purchased in either an 8 element medium aperture array or a 16 element wide aperture array. The 8 element costs less and it is designed for anyone with limited space. There are differences you should know and understand. To determine the bearing of the target transmitter the VHF directional finder [VDF] uses a transmitted signal and it evaluates the angle of the RF wave front as it passes over the VDF antenna site. In a perfect scenario the target transmitter will be easy to locate and its position will be precise. However since we don't live in a perfect world that means there is a constant battle to reduce the obstacles to a level that is acceptable for accuracy. Each obstacle causes an aberration in the wave front that crosses the VDF antenna. The wave front isn't a simple plane. There will be several waves moving in directions that are different from the transmitter line. This causes different systems to respond differently and the VDF will evaluate all of the RF Field. VDF systems are required to provide excellent instrumental accuracy and to provide RMS and maximum peak error logging. This summarizes in a nut shell but the entire process is actually quite complex. It's not nearly as important for you to understand all the details as it is to understand the general process. There are certainly some benefits to the use of low cost aperture antenna systems for VDF. The smaller size and lighter weight are perfect for installations where space is limited and there are proper structural supports such as found on a ship. This will meet most customer requirements. To achieve maximum cost effective performance over a full range of operating conditions Servo recommends a system configuration that uses the standard wide aperture with a 16 element DF antenna. This achieves maximum cost as well as performance. This antenna is used continuously with hundreds of international and domestic locations for more than 50 years so the proof is definitely there. Using a marine radio direction finder doesn't have to be as difficult as it sounds. Isn't it time you took note of what's been proven to work well over the years. About The Author: Jed has been working for leading leading retailers of marine electronics with over 10 years of experience in the maritime industry. Come to http://www.marine-electronics-now.com to get free advice on different range of marine electronics |
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