DX Engineering 4-BTV, Руководство по установке

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these "coupling radials" that you need will vary from one installation to another, but you may need
fewer than would be required for a high performance elevated mount or ground mount where there
is no metal roof. They may be resonant lengths, unless space is a concern. Many short radials may
get the job done for the lower frequency bands, too. In this installation, the antenna mounting
bracket, the coax shield, and the radial system may need to be kept insulated from the mast and
metal roof, to allow the coupling effect to work properly. Actually connecting the metal roof to the
radial system
may work better for your installation. This is another example of the fun of HF; where
changing a simple electrical antenna connection may dramatically improve your antenna system
performance.
Ideally, a quarter-wave vertical is physically mounted in the center of a metal roof ground plane.
This would provide the best omni-directional low angle radiation pattern. However, mounting a
structurally sound vertical antenna at the center of a roof is not always possible. It is true that
mounting the vertical at one end of the roof will affect the omni-directional pattern. However, the
signal reduction of a few dB in the direction away from the metal roof, or any very good radial
system, will not prevent you from enjoying the low angle pattern and resulting DXing benefits
of quarter-wave vertical!
Consider the DX Engineering Vertical Feedline Current Choke kit model
DXE-VFCC-H05-A , to
make up for deficiencies in the metal "ground plane" or radial system. This choke and its properly
mounted insulated shelf kit isolates the feedline, balances currents on the system for maximum
signals, and offers the additional advantages of reduced noise and RFI/TVI.
You can expect your large area metal ground plane or radial system to make a quarter-wave vertical
resonate especially low in frequency and exhibit an impedance below 50 ohms at the feedpoint. IF
that happens on your system, congratulations! You are the proud owner of a highly efficient
quarter-wave vertical antenna system! Now, adjusting the antenna for minimum SWR at the desired
frequency and re-matching the feedpoint to the feedline may require some additional adjustments,
as discussed in the Tuning the Hustler
®
section of this manual, including the addition and use of a
simple Vertical Matching Network, model DXE-VMN-1 .
DXE-VMN-1