Showing posts with label loop Yagi. Show all posts
Showing posts with label loop Yagi. Show all posts

Tuesday, June 22, 2010

What are loop Yagi antennas and why can’t you use them at HF frequencies?

Q What are loop Yagi antennas and why can’t you use them at HF frequencies?

A No one said that you couldn’t use a loop Yagi on the HF bands, but you’d really be pushing the envelope of practicality!

Loop Yagis are members of the quad family since each element is a closed loop of approximately one wavelength at the operating frequency. Line up a number of loops on the same boom and you create a fairly high-gain antenna. The loop Yagis in Figure 3 can develop about 20 dBi gain (each) at 1296 MHz, but the individual loops are only a few inches in diameter. That’s a substantial amount of gain in a relatively compact space.

But imagine supporting a similar collection of one-wavelength loops at, say, 14.2 MHz. The antenna would be monstrous! If you’re a lover of rotatable loop-style antennas at HF frequencies, a traditional quad design is far more practical.



Figure 3—Twin loop Yagis for 1296 MHz.

From QST March 1999