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)

Palomar Horizontal Loop Config 2022 300x202 - Loop Antennas

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

Palomar Vertical Loop Config 300x198 - Loop Antennas

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.

FB68-43 - .375" ID, RFI Range RFI Freq: 25-250 MHz, Unun/Balun Range: 1-200 MHz

Name: FB68-43 - .375" ID, RFI Range RFI Freq: 25-250 MHz, Unun/Balun Range: 1-200 MHz
SKU: FB68-43-1
Price: 0.89 USD
Availability: InStock

Store/Ferrite Core Products/Mix 43/Slip On - Mix 43 - RFI Range 20-300 MHz

SKU FB68-43-1

$0.89

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FB68-43 - .375" ID, RFI Range RFI Freq: 25-250 MHz, Unun/Balun Range: 1-200 MHz

Store/Ferrite Core Products/Mix 43/Slip On - Mix 43 - RFI Range 20-300 MHz

Product Details

Initial Permeability (@ 10KHz): 800

Material: NiZn

Max cable size - in/mm: .375

OD (A) - in/mm: .687/17.45

ID (B) - in/mm: .375/9.5

Length (C) - in/mm: .5/12.7mm

Z (ohms per bead - single turn 10 MHz): 40

Z (ohms per bead - single turn 25 MHz): 58

Z (ohms per bead - single turn 100 MHz): 83

Z ohms (per bead - single turn 250 MHz): 100

Case/Box lot size: 679

Ferrite Slip On Bead, ID = .375in/9.5mm, OD = .687/17.45mm, height = .5/12.7mm, Mix 43 - excellent for small inductors using Mix 43 material or inductive compensation on outputs of baluns or ununs.or RFI suppression from 25-250 MHz