Re: [loopantennas] Questions for the loop experts for MW Dxing
- The National Radio Club has some good handbooks on building a
good receiving loop for MW DXing.
My experience has been for best nulls you want a BALANCED loop.
That means one side of the loop is not grounded. Both ends of the loop
are above ground with a center-tap, usually used with a balanced preamp.
Tuning capacitor should be mostly symmetrical, not one side connected
to a big metal frame.
Using one of the newer one-turn broadband active loops solves many
problems. No tuning capacitor is used so the loop is well balanced
Single-turn broadband loops have excellent nulls. No cumbersome remote
tuning capacitor needed if mounted outdoors.
73 - Todd WD4NGG
In a message dated 6/30/2013 4:38:25 P.M. Eastern Daylight Time,
1. What is the main factor in determining loop nulling ability? Size of the
loop, sharpness of tuning (Q), spacing of the wires, shape (Round or
square), number of turns, etc.
2. Is there a significant difference in nulling effectiveness between an
air-core loop and a ferrite bar antenna (like the twin-coil sold by Crane)
I want to buy (or make) a loop with excellent directivity, maximum size
about 16 inches. Tuning capacitor of pretty good quality.