Skip to main content

Goofy Antennas That Work. Post #1063.


If you can't view this video, please insert this title URL into your browser search box: https://www.youtube.com/watch?v=HzWfeQVdtzY.

In this video, Stan Gibilisco (W1GV) offers a brief tutorial on two HF antennas which have been with Amateur Radio since the dawn of the technology.  Stan calls these antennas "goofy" because they appear to work when common wisdom says they won't.

The first antenna is the familiar dipole antenna, which consists of two 1/4 wave length horizontal elements fed in the middle with unbalanced coaxial cable.  The theoretical impedance of the horizontal 1/2 wavelength dipole is around 73 ohms (this will vary depending how close the dipole is above ground level). Even though there is a small mismatch between the impedance of the dipole and the 50 ohm coaxial cable feedline (around 1:4 to 1), the antenna will perform well on its designed band of operation.  To get multiband use from this antenna, just connect balanced feedline (450 ohm ladder line, 300 ohm television twin lead, or homemade 600 ohm balanced line) to a 4:1 current balun and run a short length of coaxial cable to an antenna transmatch (i.e. "tuner").

The remaining example of an unconventional antenna that works is the classic "Zepp" antenna once used on Zeppelin airships during the 1920s and 1930s. Unlike the current fed dipole, this multiband HF Amateur Radio antenna is voltage fed and exhibits a high impedance along its 1/2 wave length horizontal distance (anywhere between 500 to 5,000 ohms).  This antenna should be fed with a 1/4 wave length of balanced feed line attached to a balun, which is then connected to an antenna "tuner."  One leg of the balanced feed line is attached to the horizontal element, while the other leg of the balanced feed line is left unattached.

The video does a good job of explaining the general theory and operation of two classic antennas.

For the latest Amateur Radio news and information, please visit these sites:

http://www.HawaiiARRL.info.
https://oahuarrlnews.wordpress.com.
https://bigislandarrlnews.wordpress.com.
http://www.kh6jrm.info (breaking news for radio amateurs).

Other sites of interest:

http://hawaiisciencedigest.com (science and technology news for radio amateurs).
https://hawaiiintelligencedigest.com (trends in geopolitical intelligence, strategic forecasting, terrorism, and cybersecurity).

Be sure to check the blog sidebars for more antenna and propagation articles.

Opinions expressed in this blog are mine unless otherwise stated.

Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).

Comments

Popular posts from this blog

G5RV Multi Band HF Dipole Antenna. Post #1555.

If you can't see the video, please insert this title URL into your browser search box: https://www.youtube.com/watch?v=aeNHIQ_j4Dk This well-produced and richly illustrated tutorial on the classic G5RV HF Dipole Antenna was presented to the Brandon Amateur Radio Society in Brandon, Florida in 2017 by Bernie Huth (W4BGH).  Bernie does an excellent job of  explaining the pros and cons of this popular HF antenna from the late Louis Varney (G5RV).  Although Varney envisioned his design primarily as a 3/2 wavelength antenna for the 20 meter Amateur Radio band, radio amateurs have used the antenna for multiband use.  The G5RV is an excellent choice for the 20 meter band.  Performance on other HF Amateur Radio bands is good enough to qualify as stand alone HF antenna if you can only erect one HF antenna. For the latest Amateur/Ham Radio news and information, please visit these websites: http://www.HawaiiARRL.info. http://www.arrl.org. http://www.arrl.org/arrl-audio-news (a wee

Amateur Radio Bicycle Mobile Setup. Post #1554.

If you can't see the video, please insert this title URL into your browser search box: https://www.youtube.com/watch?v=2zWb-KnkGdY. Here's a way to use Amatuer/Ham Radio while you work on shedding a few pounds in useful exercise.  Why not equip your bicycle for 2 meter/70 cm mobile operation? In this short, well-made video, "taverned" shows us how he used a mag mount antenna, a simple C clamp, and a basic ground system to convert his mountain bike into a mobile station.  The project is straight forward, simple, and gives you emergency communications while you peddle down the road. For the latest Amateur/Ham Radio news and information, please visit these websites: http://www.HawaiiARRL.info. http://www.arrl.org. http://www.arrl.org/arrl-audio-news (a weekly podcast which is updated each Friday afternoon). https://hamradiohawaii.wordpress.com. https://bigislandarrlnews.com. https://amateurradionewsinformation.com (Amateur Radio News & Information).

An 80-Meter Vertical Helix

Like many amateur radio operators, I live on a small lot surrounded by neighbors, utility lines, and civic-minded citizens concerned about the "attractiveness" of my community.  Whether by design or outright fear, I've adopted the "stealth" approach to ham radio antennas.  It's the old "out of sight, out of mind" idea applied to amateur radio antennas. The amateur radio press is full of articles describing the struggle of amateur radio operators to pursue their hobby under the burdensome regulations of CC & Rs, HOAs, and other civic minded citizens who object to antenna farms.  So far, my modest verticals, loops, and inverted vees have blended well with the vegetation and trees bordering my small backyard.  Vertical antennas have always been a problem because of the limited space for a radial system.  There are times, however, where a shortened vertical for the lower HF bands (such as 80/75 meters) is necessary where horizontal space is lack