Loop antennas may be constructed in many forms including horizontal full wave loops in square, rectangle or triangle (delta) shapes. They can also be in the vertical plane and are most often in the same shapes with the delta being very popular as it has both vertical and horizontal polarization. The impedance at the loop resonant frequency is approximately 100 ohms but will very slightly on harmonics. Loops are “quiet” antennas compared to verticals and dipoles and are omni-directional. The also exhibit gain on harmonic bands. Once you try a loop antenna you will know why they are so popular with old timers but still a secret to newcomers. Shown below are some typical designs:
Full Wave Horizontal Loop Antenna (a.k.a Skyloop)
This antenna is horizontally polarized and should be mounted as high as possible but works well at low heights of 10-30 feet. They are quieter than a dipole or a vertical, have a broader bandwidth and will usually out perform a dipole antenna.To determine the approximate circumference in feet of a full wave loop antenna use the formula:
1005/Freq in Mhz = length in feet.
The feed point impedance of a full wave loop antenna is theoretically in the vicinity of 120 ohms and requires a 2:1 impedance transformer (for single band loops or a 4:1 balun to match on multiple bands) with 50 ohm line. You will also need a feed line choke or better yet, just get the Hybrid 4:1+1:1 in a single box.
Vertical Delta Loops
Vertical delta loops can be oriented several way but the most popular is to have the “pointy” end at the top (usually a single support) and the lower horizontal ends just out of reach of humans and animals. Best feed point is 1/4 wavelength (246/f(mhz)) from the top point down one side. Vertical delta loops use the same 2:1 baluns as the horizontal loops or 4:1 for multi-band operation.
MAXI-CHOKER Features:
- Uses proprietary Multi-Mix(TM) technology for maximum choking (up to 5K ohm) and maximum bandwidth
- 1.5 KW or 3 KW PEP Option, 50 ohm SO-239 connectors In dual screw terminal output for ladder line or dipole driven element, etc. effective 1-61 MHz
- Up to -48dB common mode suppression solves tough RFI issues
- Works for all coax fed antennas from 1.8-61 MHz (160-6 meters) - excellent for multi-band beams, verticals, dipoles, off center fed antennas, tri-band beams.
- 2-5 times more choking resistance, wider bandwidth and higher power then competing filters
- great replacement choke for G5RV/ZS6BKW antennas or as a 1:1 ladder line to coax interface for Flagpole OCF type antennas with high common mode choking to isolate the coax braid from becoming part of the antenna.
- Available with ground lug/internal static bleeder option
- Excellent replacement for Hygain BN4000D balun used on beam antennas
MAXI-CHOKER feed line chokes are used to suppress common mode current carried on the outside of the coax braid which is often responsible for receiver noise and RFI in the receiver/transmitter. These chokes are very useful for suppressing RFI common mode current at the antenna feed point or at a ladder line to coax junction, like a G5RV antenna.
Note: Color may be white or black depending on on inventory at time of order. Also available with SO-239 in/Out (MC-1-1500 or MC-1-3000) or with static bleeder/ground (MC-1-1500GB or MC-1-3000GB).
