Friday, July 6, 2018

Ham Radio HF Antenna For Limited Space, Post #1546.


Ham Radio HF Antenna For Limited Space, Post #1546.

https://www.hamradiosecrets.com/ham-radio-hf-html.

Author:  Claude Jollet (VE2DPE).

Accessed on 06 July 2018, 2050 UTC, Post #1546.

According to Claude Jollet (VE2DPE), it's possible to erect an efficient half wave length HF dipole antenna without the usual space requirements.  By carefully adjusting the configuration  of a dipole, you can squeeze nearly full dipole performance into a restricted space without losing much in the way of performance.

To do this, Claude recommends three simple HF dipole models which are easy to make, efficient, and inexpensive:

The "Full Slope" Dipole.  Just cut the HF Dipole to the desired length and suspend one segment on a tall structure, such as a homemade mast or nearby tree. Run the other antenna element to a convenient support stake near ground level.  The transmission line should be routed at a 90-degree angle from the sloper for at least a 1/4 wavelength.  The antenna will have an omnidirectional pattern, with some small gain in the direction of the slope.

Inverted "V" Dipole.  A classic antenna that drops the elements into a v shape from the horizontal.  The angle between the elements should be at least 90-degrees. You may need a choke balun in the transmission line to keep RF from the elements off the coaxial cable.

Inverted "U" Dipole.  The horizontal portion of the dipole runs for approximately 60% of the normal horizontal length, with the remainder of the antenna elements drooping down and supported by ground stakes.  Jollet says "most of the RF energy radiated by a half wave dipole is concentrated in the middle 60% of the antenna."

Try some of these limited space antennas and see if they work for you.

Thanks for joining us today.

Aloha es 73 de Russ (KH6JRM).

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Aloha es 73 de Russ (KH6JRM).