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Yagi versus Loop Antenna Patterns

yagi versus loop antenna patterns

When you compare Yagi versus loop antenna patterns, you won’t find as much difference as you may have expected.

Previously, I have provided anecdotal evidence about how well my wideband loops perform compared to a real ham antenna on a tower. Recently, I modeled both of these antennas in software. Here are some scientific results from 4NEC2.

Above, you can see the Yagi versus Loop antenna patterns. Yagi patterns are blue, loop patterns are red. You can see elevation patterns in the top row, while the azimuthal or directional patters are in the lower half of the picture. You can see comparisons on 9.5, 14.2 and 15.5 MHz, covering the middle of HF.

Outside of its design parameters, particularly down at 9.5 MHz, the beam looses much of its directional advantages, both horizontally and vertically. However, for most angles and directions, it maintains a 10 dB advantage over the loop. This confirms my anecdotal evidence of the beam performing 6-10 dB better is most cases.

But not all. You can see that for higher elevation signals, and off the sides of the beam, the tiny magnetic loop at ground level holds its own or actually has more gain than the bigger antenna. But only by a few dB.

So definitely, when used as a general SWBC antenna, a beam or a dipole will give you some advantage in directivity and low-angle reception. And since they cost an order or magnitude more (10x) to install, no surprise.

Yagi versus Loop Antenna Patterns and RFI

Conventional wisdom is that loops are lower noise antennas. In general, this is true but not always. My beam’s directivity can null some local RFI if I point the nulls in the right direction. And, at these frequencies, loops loose most of their nulls for far-field interference.

But in general, if you are willing to accept a few less S-units, you can get as much fun out of wideband loops compared to “real” antennas. And, of course, you do so in a lot less space horizontally and vertically. The red lines above show loops get pretty close to full size performance.

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