Antennas

Simulations and testing are shown in these articles about ham radio, and a few other, antennas.

43 Foot Vertical Pops a U-Bolt

The top U Bolt holds while the bottom just hangs there.

Another title might be… “43 Foot Antenna, the Tilting.”

NOTE: UPDATE AT END OF THIS POST

We had a big blast of cold air come down from Canada last night. Temperatures reached the teens and winds peaked at 50 mph. No problem I thought… “My DX Engineering 43 Foot Vertical has been up in weather like this since 2008 and does exceptionally well.”

The morning was busy gathering up blown away things and mounting a search and rescue of my car cover. Often this car cover sweeps around the house so I walked out back.

My eyes scanned the back yard for the cover. HORROR! I looked up to see a not so vertical antenna against the December backdrop of a cornfield and morning sky. Figure 1 reveals my shock and awe moment…

Read more

Dallas Cowboys, DTV, Wife and Hex Beams

So what do the Dallas Cowboys, Digital Television over the air broadcasts, my wife and the Hex Beam have in common…

You’re probably thinking…

“Man… John has lost it. He’s blogged one post too far… On Halloween afternoon too…”

Hang with me for a moment.

Read more

Dipole Generates Static in PL-259

Irrespective of the fact the solder-the-braid PL-259 connector is probably the worst RF connector conceived by the mind of man1 and the fact the spark shown in the video is in an area that should be a direct short, the video, shown below, wonderfully shows the ease with which static charge can build on a dipole antenna.

That’s not the point though. If we were to cut off the connector we would surely still see a spark from center conductor to shield. If the cable were near station ground we would expect a spark jump. That large a charge has to go somewhere.

Read more

Magnetic Mount Antennas Don’t Suck

Mag Mounts. Bum Rap?

Over the years I have heard amateur radio folks, CBers and scanner fans bash the use of magnetic mount antennas. Concerns include flying off the vehicle and becoming a projectile during an auto accident. Other concerns relate to performance and stem primarily on how well the shield of the coax is electrically connected to the conductive body of the car.

I cannot comment on the mechanical realities of the antenna flying off the roof during rapid changes in speed, but can say I have never seen one do so. I encourage anyone with data to propose their article to this web site

So…

Addressing the Mag Mount Electrical Questions

Let’s talk about the electrical conductivity of a standard mount vs. a magnetic mount antenna. Here is a quote from the newsgroups concerning antennas for scanners…

Read more

Small Loop HF Mobile

In the never ending quest to improve our HF mobile ops for the Virginia QSO Party we finally decided to try a small loop.

There is nothing new about small loop antennas. They have been discussed in the literature for decades. The ARRL has some very old articles about them in the 1968 March and July editions.

Constantine A. Balanis’ book on Antenna Theory discusses and defines large vs. small loops. This book is an essential reference if you seek the details on how loops work. The loop described below fits into the “small loop” category where the currents along the conductor are, for all practical purposes, constant. This is unlike full size antennas where current reaches a minimum where voltage approaches maximum. Since this loop is electrically short with respect to wavelength, current does not change “much.”

Read more

43 Foot Antenna Installation – The Rising

Here are some details regarding the next, and probably last, phase of my 43 Foot DX Engineering vertical installation.

This post is very late. The actual date of the events within it are just before March 2009 in preparation for the Virginia QSO Party.

In the many posts within this site, it is no secret my examination of various vertical antenna solutions with comparison between BigIR and the 43 Foot products a big part of this. Check out all the 43 Foot posts on HHD here…

Read more