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.
The PAL-OCF2006 covers 20-17-15-12-10 and 6 meters in a length of 32 feet. In most cases, no antenna tuner is needed and switching bands is as easy as changing the band on the radio. Super convenient and quick – great for contest operation! Choose 500, 1500 or 5000 watts PEP power levels.
Uses hybrid balun containing wide band 4:1 transformer + 1:1 common mode feed line choke to keep all your power on the antenna and off the feed line coax outer conductor!
Unlike Buckmaster OCF antennas (at twice the price, and no WARC band or 15 Meter operation), you can transmit and receive on 6, 12, 15 and 17 meters with our OCF - Better engineering and lower price - only from Palomar Engineers!
Also much quieter than end fed antennas!
INSTALLATION
For best results support balun at 30+ feet and ends over 15 feet. Angle of feed each side must be great than 45 degrees or 120 – 180 degrees total between each side preferred. Any length of 50 ohm feed line ok but longer feed lines over 50 feet may show reduced SWR on some bands due to losses in feed line and soil conductivity, nearby objects, etc. Due to local ground conditions, antenna height and feed line length, SWR may vary from samples shown and an internal or external antenna tuner may be required or some bands to bring SWR at end of feed line to acceptable levels. Overall length is 32 feet (7 feet and 25 feet sides).
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NEED and END FED antenna covering the same bands but shorter at 25 feet and only requiring 2 supports? Check out the BULLET-2006
SWR TECH NOTE:The SWR graphs shown are specific to the conditions listed including antenna height, configuration (flat top, inverted V, inverted L, etc.) and direction, feed line length and type, geographic location and soil condition, calibration and accuracy of SWR instruments used. Your SWR measurements will probably be different and manufacturer takes no responsibility or liability for these differences beyond the purchase price of the antenna.
