Loop Antennas

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.

 

RG-400 Coax Jumper Cable with PL-259's on each end - 6 inch pigtail, Double Shield, High Power

SKU RG-400-6IN
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RG-400 Coax Jumper Cable with PL-259's on each end - 6 inch pigtail, Double Shield, High Power
Product Details

This cable is 50 ohm and short 6 inch pigtail double shielded with foil and braid and PL-259 connectors on each end. All the connections inside are soldered and the cable is made of copper conductors with coax having PVC jacket. RG400 is generally useful up to 5000 watts PEP at HF frequencies below 30 MHz. Greater power capability and frequency range than RG-8X, yet similar physical size.

Use for short jumper for Palomar Engineers Noise Filters like CMNF-500-50 or SWR meter, etc.


** Our Customers also used this RG400 Coax in longer sizes to make ham radio common mode chokes up to 5KW PEP

Physical Specifications:

• Inner conductor: Silver Plated Copper, Diameter: 19x0.203mm

• Dielectric/Insulation: PTFE, Diameter: 2.95mm

• Outer Conductor/Double-Shield: silver plated copper double braid , Diameter: 3.95mm

• Jacket: FEP, Diameter: 4.95mm

Electrical Specifications:

• Nom. Capacitance Conductor to Shield: 105 pF/m

• Nom. Characteristic Impedance: 50 Ω(ohm)

• Nom. Velocity of Propagation: 70%

• Min. Bend Radius(Install): 25mm

• Voltage Rating: 1900 VMS

• Max. Operating Frequency: 12400 MHz

• Operating Temperature Rating: -55℃ ~ +200℃

Attenuation:

• 100 MHz : 0.144 dB/m

• 400 MHz : 0.295 dB/m

• 1,000 MHz : 0.482 dB/m

• 5,000 MHz : 1.184 dB/m

• 11,000 MHz : 1.899 dB/m