Quality Space Antennas Take A While To Build

So as a result of building the Turnstile Moxon Rectangle antenna for satellite operations I have learned that constructing a well-built antenna takes a LONG time. I am currently having issues tuning the phasing stub of the 70cm Moxon rectangle. I found I needed to cut the driven elements down about 1 inch due to the center PVC spacing and the end bent portions of the elements were longer than they were supposed to be. A few more hours playing around with the antenna getting the right adjustments should be enough to finish the main part of tuning. Phasing and matching stub lengths truly are crucial to this satellite antenna. The article describing the construction in detail of this antenna will be hosted on www.CollegeARC.com.

Turnstile Moxon Rectangle

Here are some pictures of my turnstile moxon rectangle satellite antenna that I am building.




Thats just the 2m antenna, I will be writing up a larger more in depth article on www.collegearc.com in the near future.

Hustler 5BTV Antenna Series

A collection of my posts documenting installation and tuning of the Hustler 5BTV Antenna by the New-Tronics Corporation:

1. Hustler 5BTV Antenna Radial Installation
2. Hustler 5BTV Antenna Completed
3. Hustler 5BTV Antenna Performance Results
   

Hustler 5BTV Performance Results

Here are the performance results from the Hustler 5BTV (4BTV with 80M add-on). Click on the image for a larger view. This is the data before I built the final transceiver end 1:1 balun, its the temporary balun (black coax). Also, 80M was not tuned and 40M was not quite finished being tuned but close. 10M is also almost a 1.1:1 SWR across 28-29MHz band From left to right is MHz, SWR, resistive impedance, reactive impedance, and overall impedance.

A word to the wise, DO NOT BE FOOLED BY SWR! A perfect 1:1 SWR does not mean that the antenna performs well or radiates efficiently. a 50 ohm resistor at the end of the coax with give a 1:1 SWR but I can guarantee that you will not contact anyone unless the sunspot cycle is incredibly active, there are stories of people making contacts on dummy loads... but you get my point!

The most important column is the reactive impedance (Xs) information. The Hustler 5BTV antenna is resonant when the reactive impedance is 0 ohms. The closer to 0 ohms the more efficient the antenna is at radiating the RF. Even if this value shows an SWR of >2:1. Yes, there will be loss in the coax due to the SWR mismatch but more of the RF getting to the antenna will be radiated.



A great explanation of this is on the ARRL TIS (Technical Information Service) article titled "Why an Antenna Radiates" written by By Kenneth Macleish, W7TX
in QST November 1992.

"Both kinds of resistance dissipate energy at a rate equal to the resistance times the square of the current. Of course, energy dissipated this way doesn't actually disappear. An alternating current, flowing against radiation resistance, turns electrical energy into radiant energy, which wings its way off into space. Current flowing against ohmic resistance transforms electrical energy into heat, which is mechanical vibration of the atoms of the conductor -- the atoms vibrate when they're hit by the moving free electrons"

I hope this post helps and provided a lot of information on the Hustler 5BTV antenna as well as a better understanding of antennas in general. While I haven't perfectly tuned the antenna yet its in "the ballpark"! Please let me know any comments or suggestions or if you have any questions!

Bryce
KB1LQC

Hustler 5BTV Antenna Completed

I finished my Hustler 5BTV (5 Band Trapped Vertical) antenna and here are some pictures to show it while testing and prior to burying the coaxial cable.

First off, here is the radial base which does not employ a radial base plate. I simply attached the radials to the base mount. The base of the antenna is 4" off the ground per the instructions from Newtronics/DX Engineering.


The radials fan out and fake the antenna into thinking the ground is more conductive than it really is. The more radials the better. I plan to eventually keep adding radials over time, some longer ones, maybe 1/4 wavelength at 80M over 180 degrees could happen, the other 180 is about 10 feet from my property line, so I'm not going to bother! Many small radials along the property line will do a lot better than the current zig-zag I have right now.

I wound a coaxial cable 1:1 choke balun with the RG-8 and a 6.5" paint can as a form (in the background). The manual asks for 6" but this is fine and its not critical to get exactly 6 inches. The balun simple stops any induced (from the energy being radiated by the antenna) RF traveling down the outside of the coaxial shield as there should be NONE, due to the skin effect it stays on the inside shield of the coaxial cable closest to the center. The balun DOES NOT inhibit the RF in the cable, only on the outside. I made sure it would keep its form, hence the duct tape, while the RG-8 provides enought stiffness with plenty of margine! I used wire ties going through a slit in the duct tape on the second, and second to last windings to provide strain relief for any tension on the coax.

Ok, the next picture is not really good I will appologize for the blurryness (I would love to own a Nikon D80 SLR after taking a non-photo major photo course at RIT... but my point and shoot has to do!). Using a borrowed MFJ-296 Antenna Analyzer I tested and tuned the antenna. The Hustler 5BTV requires that a choke balun be placed no more than 8 feet from the antenna AS WELL AS 8 feet from the transciever. If you do have one you MUST have both, they trap the RF on the outside shield to bounce between each balun, eventually attenuating (turning into heat). If the second is not used at the transmitter there will be a large SWR mismatch (>31:1 according to the MFJ-269). I wound a quick test balun with some spare coaxial cable. During this testing I identified the corroded adapter near the antenna feedpoint which was eventually replaced so that no adapter was needed. I also located myself as far as possible from the antenna while measuring to reduce any influence I may have on the antenna.

Lastly here is the final balun that is now used with the Yaesu FT-897 transciever on 80-10M in the radio room (shack!). I bought some high quality Belden RG-58 from my local independent electronics supplier, and its definitly nice stuff! It uses both a braid and foil for the outer shield and has a stranded center conductor (better flexing). Again, the paint can was used for a form and tape holds the windings together with wire ties at both ends for strain relief.


Results

No tuner is used ( I use mine in bypass mode) and the antenna is close to a 2:1 match on all bands! The bandwidth on 80M is only good for the phone band but its not the greatest resonater down that low either! I was up testing the transciever balun around 1 AM Sunday July 26, 2009 and heard several VK stations! That's Austrailia which I have rarely ever heard. What struck me as amazing was that I was on 20M (14 MHz) at 1:30AM listening to Austrailia. First off, most of the time 20 meters dies at night and while there was probably some great propagation that night as compared to normal, being able to clearly hear several station in VK land with such little background noise was amazing. The Hustler 5BTV definitly turned from a fancy aluminum rod shoved into the ground into a vertical antenna with a low takoff angle. The radial system is the difference between night and day!

I have linked to the audio recording of VK4MA that was heard on the Hustler 5BTV. Notice how little background noise there is considering my area of Massachusetts is relatively noisy. I switched to no antenna near the end but didn't edit it out of the recording.

Audio Recording at 1:30AM on the Hustler 5BTV hearing VK4MA on 14.260 MHZ

I hope this article provides enjoyment and some pointers. Feel free to contact me for any questions regarding this antenna or anything else on your mind! I have notice people tweeting some of my posts and really appreciate that others enjoy some of my projects and experiences! Thanks!

Bryce

DX Engineering Hustler 5BTV Vertical Antenna

I have spent the last 3 weeks installing a ground radial system for my DX Engineering Hustler 5BTV 80M-10M (3.5MHz - 28MHz) vertical antenna. Opting for the marginal benefit of sixteen radials cut at the lowest frequency I plan to operate on. This means that each radial is thirty-three feet long! The picture to the left shows a view of the antenna and surrounding area. The two traffic cones are covering some horseshoe pit metal poles. They most likely affect the antenna but it's not the worst problem in the world!

Each radial is made of #14 wire I stripped out of three cable Romex house wire leftover from building our garage (yes we built it ourselves). I soldered ground lugs onto each end and attached them to the antenna base at the U-bolts since I do not have the radial plate.

Fanning each radial out about 22.5 degrees (just and estimate with the handy protractor), but I was not strict on the angles being exact or laying the radials exactly straight. Instead of digging trenches for each wire, simply taking a square shovel and making a long slit in the ground worked great and left minimal marks. I took a piece of scrap metal and shoved the cable down and followed with the shovel pressing the ground back into place.

It took me three weeks which consisted of about 20 hours in all of laying the wires. It could have gone much quicker but I had to get set up each time I went out to work on it because most of the time I would do this after work and only had a few hours of light. There is a compost pile right next to the antenna which I had to move for each radial, in the end the whole pile was turned over so I guess I "hit two birds with one stone". It hadn't been turn in a year or two so the tough and slow part was moving the wet flattened leaves.

Before I laid the radials for the Hustler 5BTV it performed like an aluminum rod stuck in the ground. It really didn't pick up signals well and was deaf by antenna standards. Any attempts to adjust the SWR were not easy, very touchy, and almost unable to be tuned below a 3:1 VSWR on the amateur bands. After putting these radials onto the antenna, I am able to adjust the elements as suggested by the manual with ease and so far have adjusted most bands to <1.9:1 VSWR. The picture to the right shows the base of the vertical a few days before I was finished installing the radials. The coax can also be seen which attaches under the antenna by simply splitting the sheath and center conductor appart. The Hustler 5BTV is mounted about 4 inches above the ground as suggested by the manual.

The Hustler 5BTV vertical antenna went from performing like a 21 foot aluminium rod stuck in the ground to a 80m-10m antenna! Using an MFJ 269 antenna analyser has been great and I hope to have SWR data and operating performance soon. The 4BTV is exactly the same except there is an extra trap and whip antenna attached to the top which makes the 5th band (80m).