Category Archives: Antennas

3-element Tape Measure Yagi

I’ve been wanting to build an antenna for radio direction finding (RDF) for a long time. I finally got the motivation to build one, so here are a couple pictures of the design from the ARRL Antenna Book. For pictures and more explanation from my build, check out the Projects Page.

Here is the design schematic.

Here is the matching section where the coax connects to the driven element.

It was a lot of fun to build and very easy to do. I recommend it for anyone interested in RDF or who needs a portable yagi for anything (including satellite work)!

To view more about the project, check out the specific Project page, called Tape Measure Yagi.

4-element Tin Foil Quad

With the ARRL VHF Sweepstakes coming up this weekend, I wanted to construct a directional beam antenna for use on one of the local mountains for some of the contest. I wanted something that is simple, cheap, quick, portable, and, most importantly, effective. I thought back and recalled a single element quad antenna for 2-meters that I had constructed in college, for my amateur radio club to use locally. I wanted to make it more effective, so I decided to try to work out a design for a multiple element quad for 2-meters.

Here’s what a quad antenna looks like. This is a 2-element design.

My “design” will have four elements, a reflector, driven, and two directors. This will help to focus the beam of RF energy into a more concentrated and condensed area. That basically helps to add gain and sensitivity in the direction that the beam is pointing. The elements will be taped to square (diamond) shaped pieces of cardboard, and will be made of one strip of tin foil, 1/2″ wide, in a way that will trace the edge of the cardboard. The completed cardboard elements will then be placed in to slits made in the bottom of a large cardboard box, which will sit on its top as a support for the antenna. Tuning (if necessary) will be achieved by placing the driven element in different pre-tested and tuned slits.

Here’s what my design looks like so far. Crude, isn’t it?

Last night, I bought some of the supplies that I will need. 50ft. of RG-58 coax. I asked at the local Lowe’s if they had a cardboard box that I could have, because I will need to have one about 5ft. in length to accommodate the elements of the antenna. I already have tin foil and solder / soldering iron at home. That’s about all I will need. I will post this project, along with pictures, once it is completed, on the “Projects” page.

Dipolish Thoughts

Lately, I’ve been wishing that I had a better way to get out on 20-meters, 40-meters, and 75-meters. The 75- and 40-meters are a bit long for the small amount of space that I have available to hide an antenna (local residential, contractual restrictions), but I did some measuring around, and I think I found an ok spot to try to string a dipole!

Check out these drawings I made late at night (mind I’m no artist).



Probably hard to conceptualize my diagram in your mind, but I have a deck over a patio outside of the “Shack.” There are 4 beams that support the deck that I believe I can string the dipole from! I will try to get the supplies and cut this to length very carefully–I don’t have an antenna tuner. I’m hoping I can also tune on 10-meters, as a full wave dipole. I will probably post pictures and such on the Projects page as I go.

Sea Water Antenna

I posted this on my Twitter when it came out, but I wanted to re-post it here, to share again. This is a sea water antenna that was designed and can be used in a variety of applications. I thought it was a very neat concept, and I would even like to try building one. It isn’t high on my priority list right now, but it would definitely make for a fun and interesting experiment.

SPAWAR Systems Center Pacific has developed a technology that uses the magnetic induction properties of sodium chloride (salt) in sea water to create a UHF/VHF/HF antenna.

(From http://www.southgatearc.org/news/october2010/sea_water_antenna.htm)

Fractal Antennas

I’ve been doing some reading on fractal antennas lately, after having disregarded it the first time I came across it some time ago (thanks, David). It’s seeming to intrigue me quite a bit, and so I am contemplating a project to construct some form of fractal antenna for use, perhaps, on UHF/VHF. I will continue to research online and try to find or create a suitable pattern/layout for the elements. If you have any knowledge, experience, or information otherwise about fractal antennas, please leave a comment here!

Credit: http://www.freepatentsonline.com/7019695.html

http://www.freepatentsonline.com/7019695.html