A Hawaii-based Amateur Radio Antenna Blog focusing on the theory, design, and use of homemade antennas.
The Amazing Doublet Dipole G5RV--Best Stealth Backyard Antenna
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If you can't see the video, please insert this title URL into your browser search box: https://www.youtube.com/watch?v=rvBuzQT8zsc. This is post 2258 in a continuing series of simple ham radio antennas.
Thanks to "Ham Radio CQ" for this exceptionally well-done presentation on a backyard stealth antenna that would be ideal for those home-bound during the annual ARRL Field Day.
Here are some operational and equipment tips from the author. This list is extensive and should give you enough information to get started on this multi-band HF antenna:
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Dipole Doublet ~ Best Stealth Small Backyard Antenna for Ham Radio
he doublet antenna is a form of dipole that uses a balanced feeder, often open wire feeder and an antenna tuning unit. As open wire feeder is able to operate with levels of standing waves and effectively becomes part of the antenna, it is able to operate over a wide band of frequencies.
As a result, the doublet antenna forms a very convenient multiband antenna and it is often used at HF where a number of different HF bands need to be covered, and it is relatively popular with radio amateurs where it enables several bands to be used with a single antenna.
Doublet antenna basics
The doublet antenna is essentially a balanced system and each half of the top plus each wire in the feed line must be equal in length. The antenna top is not cut to resonate at any particular frequency (unlike the half-wave dipole), and any length may be chosen to suit an individual location.
Basic doublet antenna concept
Basic concept of a doublet antenna
The key to the doublet antenna is the form of feeder used. Open wire or balanced feeders are able to operate as part of the actual antenna itself, not just feeding the power from an unbalanced source. The balanced feeder or open wire feeder is able to operate with standing waves along its length.
Note on Balanced Feeder:
Balanced feeder can come in one of a variety of forms: open wire, ladder line, or simple ‘ribbon feeder’. It provides the capability for very low loss, provided it does not pass near other objects that might cause imbalanced. Balanced feeder is often used on the HF bands.
Read more about Balanced Feeder.
Standing waves are a feature of radiating wires, but in the case of the open wire feeder, it consists of two equal length close spaced wires. As these carry equal and opposite currents their radiation cancels. However the feeder still remains part of the overall antenna itself.
For a doublet, the top section is typically a minimum of λ / 4 for each section (length L1), i.e. a total length across the top of λ /2.
However it is found that the top section, i.e. 2 x L1 can be reduced to about 3 λ / 8 without any major reduction in performance - it has about 98% of the efficiency of a half wave dipole, so the difference will not be noticed.
The doublet antenna can operate over a wide range of frequencies and as a result the radiation pattern will change according to its electrical length with respect to the number of wavelengths, or part of that it represents. As the electrical length increases, i.e. as the frequency increases the antenna increases in the number of wavelengths it represents although the physical length remains the same. As the electrical length increases, so the phasing of the fields around the radiating element mean that the radiation changes from a figure of eight pattern for a half wave top radiating element to a pattern that has lobes that increasingly move towards the axis of the doublet antenna."
If you can't see this video, please insert this title URL into your browser search box: https://www.youtube.com/watch?v=xgOqP8uPEPc. Here's an interesting antenna design for radio amateurs exploring the 630 meter and 2200 meter amateur radio bands. This classic antenna is basically a top loaded vertical designed for frequencies below the standard broadcast band (472 kHz and 137 kHz). Even though this antenna is inefficient, a digital signal using the FT8 protocol should get you some contacts. Good luck! For the latest Amateur 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). http://amateurradionewsinformation.com (Amateur Radio News & Information). http://www.southgarearc.org. https://hamradiohawaii.wordpress.com. https://bigislandarrlnews.com. Be sure to check the blog sidebars for more antenna and propagat...
If you can't see the video, please insert this title URL into your browser search box: https://www.youtube.com/watch?v=MXTYTytR56A. Don't let deed-restricted properties (HOA/CC&R) stop you from enjoying Amateur Radio. In this video from AC2RJ, we see how some well-placed trees, a camera tripod, a telescoping fiberglass mast, and a "V" antenna can get you on the air without a lot of effort. Add an antenna "tuner", a sturdy rig, such as the Yaesu FT-817, a microphone/cw key, and a simple grounding system, and you have a fully functional, nearly invisible ham station in your backyard. For the latest Amateur/Ham Radio news and information, please visit these web sites: 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 ...
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/ar...
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Aloha es 73 de Russ (KH6JRM).