Feedline September 1999
Pioneer in participative, interactive journalism.
Antennas and Where to Stick Them by Alan Cake, G3MOJ
There are a great many types of antennas and most of them function best when they are erect. This is because of 'standing-waves' which produce energy in a vertical plane. Energy in the horizontal plane requires 'lying-down waves' and this is why most of the radiated and received energy is termed 'ecstatic' rather than 'magnetic'. (Kirchhoff's fourth and fifth laws of self-immolation present a heated argument on this subject.)
One of the most famous antennas is the diamond-shaped 'Ron Bick' antenna, named after its inventor Ron Bick of Watford, England. This antenna is very good but, because of its size, it has two main disadvantages - it is difficult to erect vertically and it is of limited use in fast-flying jet aircraft.
Another antenna that deserves a mention is the Log Periodic - so I have mentioned it.
I will now move quickly onto the three 'pole' antennas, namely the monopole, the dipole and the tripole. The last-mentioned can be disregarded as it is not now in use. The reason for this is fascinating, but I can't remember what that reason is. The monopole is very useful for LF, MF and HF but has limited usefulness at VHF frequencies where one should use the stereopole if maximum enjoyment is required.
At this point the reader may feel that there has been some neglect of the technical aspect of antennas. This is true and the author intends to deal with the dipole in depth technically, but at the same time try to satisfy the natural curiosity of the non-technical reader.
The word 'dipole' is a composite of two Latin words, 'di' meaning 'six' and 'pole' meaning 'sticks'. So it can be easily seen, even by the most ignorant, that a dipole is made from six sticks. As the reader will already know from my in-depth study of the Log Periodic, six sticks will have a much wider aperture than only one stick. Now we come to the technical bit. Pushing these sticks into the ground at regular intervals will give a quasi-omniphysical deltoid stub-matching line-of-sight high incident ground-wave. If three of the 'sticks' are coated with an intensely ionised P material and the other three coated with un-ionised N material then Zowie! - it's instant Receivesville man. (It is hoped that the reader will forgive the author for occasionally lapsing into the vernacular, particularly when excited.)
Another thing about antennas that must be remembered is feeder independance. If the feeders of dipoles are spread apart it changes the natural independance of the antenna from 75 Ohms to 250 Megohms. As is commonly known it is impossible to hear anything with that sort of resistance in the antenna feeder. So best not to do it.
Other types of antennas in constant use are the 'Beverage' (called the 'T' antenna in Britain). This is also called a long wire and is 1.5 inches long at 16 Ghz. The Inverted X is is also famous but not much in use as no-one can decide which way up it is supposed to be.
Finally, we move on briefly to microwaves where there are special considerations to be taken into account. Microwave and satellite signals can 'bounce around' all over the place and can become what is technically known as 'dirty'. However, fortunately there is one antenna which can be used effectively to 'clean up' these 'dirty' signals. This is, of course, the very well-known Carbolic Dish.
Learning CW and How to Teach Other's CW by Frank Lynch, W4FAL
I finally did it.... I'm not quite sure how, but everything clicked and here I am, and EXTRA...Amateur EXTRA that is!. I told Herb, Alan, Tom, Bob, Ed, and many others that hassled, encouraged, etc. me to keep striving for this, that I'd write a short article about the experience when it was all over. So here I sit, trying to write something intelligent for those that haven't reached the plateau of Amateur Radio on how to get there.
Well it's just as hard to write how I did it as it was to do it! One thing that I learned was that what worked for someone else may not work for you. It's very different from just sitting down with a book and studying the material that's on the written question pools. At any rate I'll tell you of some of my experiences.
When you start off with nothing, there's a tendency to practice a lot with the easy letters, saving the hard ones for later. Don't do that. It's OK to start with E, T, I, M, S, O, and H, but throw some Q, Z, P, J, V's in there two. I used several computer programs and a set of tapes (for when I wasn't near the computer). Alan, K4PB wrote a neat little program that he gave me. It sends you five letter groups, which you copy down on paper and then input for scoring. Writing skills shouldn't be overlooked. Writing a 5WPM is pretty easy but most people begin to have trouble writing at 15 WPM, I know I do. So it's important to practice writing what you here. Herb, W3HL also did a neat program that to help learn CW. Herb's approach among other things, is to get accustomed to hearing the CW characters sent at about 20 WPM, with the letters spaced out enough so that you can keep up when you're starting. I also used Morse Academy a lot. You can set Morse Academy up to only work you on characters that you're having trouble with.
More than anything the key is to try and practice a little every day. I know, it's hard to do that sometimes. I was the same way, I'd skip a day, and then I'd skip the next day. It's shows when you do that too! I did a lot of that (I call it YO-YO ing.), until I figured out that I was never going to get to 5WPM if I didn't start putting some regular time in. I also had a couple of good motivators. One was that I wanted to be the Band Captain for the Novice Tech Tent at Field Day. It's the end of April and I still only have a Technician License.... GOTTA DO SOMETHING! Practice....
Then Bob, K4HA, goes off the hamfest up north and stumbles on Smithchart Calculator (one of the old circular slide rule jobs). I've been looking for one of these for years for my collection. He tells me that it's mine when I get 13WPM.... NOW THE FAT'S REALLY IN THE FIRE!
In May, I went and passed the 5WPM and also took all the written tests (General, Advanced, and Extra), just to get them out of the way so I could concentrate on the CW. Field day came and went, and we worked a respectable number of CW contacts (often with some help, but we were doing it). I didn't realize it at the time, but this was really a big help. If you're trying to get ready to take a CW test, one word -- CONTEST.. Go get in some kind of CW contest. Even if you just listen, it will help you more than you'll realize at the time.
After field day I continued working and practicing, getting up to 12 or 13 WPM with a good score in Morse Academy for 5 minutes. My score for 5 minutes at 20 WPM as not too good however. It's like I could keep up for about a minute and then I ran out of steam and started making lots of mistakes. What worked from me was to turn the character speed up to about 23 WPM and the sending speed down to about 15 WPM and practice like that a while. When you set it back to 20 WPM it doesn't seem as fast.
Several weeks pass, and now it's time for the Cary Swapfest. I have it all planned in my mind to go take the 13WPM test and get the Advanced, that is until I see Bob just before the test. He asks if I'm going and I tell him yes, that I'll go a try the 13 WPM. He says NO YOU WON'T, you'll go take the 20 WPM and if you don't pass that, then you'll take the 13... Rather than argue, I amble off to the test session, hoping that the 20 WPM won't somehow erase all I've ever known about Morse Code, SmithCharts, or Women!
I don't know what happened that day, if it was the adrenaline or what but I passed the 20 WPM. My advice is that ANY time you go to a testing session listen to the 20. If you don't pass that the 13 will seem slow when you take it. If you don't pass 13, the 5 will be easier than it would had you just listened to the five.
Another tip, get yourself a friend with a Smithchart calculator (or something else you really want) to give you some much needed motivation.
Thanks, Bob, Alan, Herb, Tom, Ed and a very special thanks to Charles, KE4CDI. His one line jabs on the repeater were a true source of motivation also. You guys are great! Frank, W4FAL
Meeting Minutes for August 26, 1999 by Herb Lacy, W3HL
The Non-Meeting - otherwise known as the Fox Hunt - was called to order at 7:00 p.m., by Will, K4IWW, hider of the Fox. There was no business conducted at the meeting. Teams were established, odometers checked, and rules reviewed. Four teams participated in the hunt.
There was no business conducted at the meeting. At the appropriate time, Will, K4IWW, activated the Fox.
As the dust settled, the order of finish was: (1) Jeff, NX9T and Charles, KE4CDI; (2) Ed, AB4S, and Suzi, WA4AKB; (3) Dennis, KA4ATK, and Darrell, KF4URC; and (4) Tom, KM4LB, and Mike, K4ZMY. Every participant learned something of value for future Fox Hunts. There is a time to plan on the chalkboard, but reality sets in when the best laid plans - in practice - go awry. We need to hold these events more often in order to sharpen our individual and collective skills in this interesting part of the radio art..
Next Meeting: Sept. 23, 1999. The program for this month is Smithcharts: How to use and abuse them!, by Frank, W4FAL. Frank will have paper copies of the color slide presentation, free Smithcharts, and a demonstration of doing solving impedance matching problems using the Smithchart. For those of you that thought you'd never see this again after EE303, you're wrong! W 3 Hatteras Lighthouse
Fox Hunt Team Reports
From the First Place finishers, Jeff, NX9T, and Charles KE4CDI. Submitted by Jeff, NX9T.
It had been several years since our last hunt so I was definitely looking forward to this event. Since my regular partner couldn't make it, I decided to hunt by myself. While at the check in site, Charles, KE4CDI was needing to ride with
someone since this was his first hunt ever. He occupied the co-pilot seat in my vehicle. Since this was Charles's first hunt, we would rely on my equipment completely. The hunt equipment consisted of a 3 element, handheld yagi, an "active attenuator", 2m HT, and a 2m mobile rig/w car mounted vertical.
When the fox first began transmitting I was having problems copying him for some reason. However, one beam heading to the S/SW was obtained. We got in my car, drove approximately ½ mile and entered a grocery store parking lot where the yagi was pulled from the trunk and a second heading was quickly obtained. It confirmed we were heading the correct direction. We drove another 1/2 mile while determining that the signal was indeed strengthening as indicated by the mobile radio. We then traveled into another parking lot at a business to take an additional heading. Now we knew we were right on top of the transmitter. Heading showed it to be on the other side of the building so we
circled and parked our car. We actually arrived at the transmitter site within 15 minutes but had some difficulty pinning it down.
After walking around the parking lot and surrounding buildings for about 10-15 minutes while carrying my 3 el. beam, attenuator, and HT (got several comments I can assure you) it was determined that the transmitter was in a the immediate vicinity of a car, a van and a bunch of plants!
We started sniffing around...and that is when Charles(who I think thought I had taken him on a wild-goose chase by now) noticed the QSL card
in the window of the van we were standing in front of! Yea! Success!! It was a learning experience for me concerning close in "sniffing".....next time....... :-)
As always, the Fox hunt was a lot of fun. Some can be frustrating but fortunately, this was one that was fun all the way around! My only regret is that I didn't take much time w/ Charles to really "teach" him much since we were in the "heat of battle"! Hopefully he received some education on how it can be fun if nothing else!!!
Thanks to KM4LB, K4IWW, and W3HL for all their setup work and coordination! 73 !!! de NX9T
From the Second Place Winners, Ed, AB4S, and Susan, WA4AKB submitted by Ed, AB4S
We drove to the intersection of Maynard and Kildaire Farms Road and knew we were getting close. We pulled into the parking lot there and Susan spotted the space shuttle. She thought that it was real. (Turns out that it was real.) She had to hop on board and try to fly it. It took us approximately 20 minutes to convince her that it wouldn't go anywhere without quarters - (valuable time lost.) We then headed for the fox since we had used our secret weapon to find out where the fox is. Susan had spotted it during her flight. (See Figure 1)
As we approached the fox site, we saw others in the vicinity, so we had to make a quick detour behind Salt Box Village to prevent the others from following us. One spotted us, and tried to run us down (See Figure 2). However, we were wearing protective clothing so no harm done. We finally managed to lose him.
In the meantime, KE4CDI and NX9T found the Fox site. WA4AKB's overhead flight helped us find it, but because of the flight and the aggressiveness of our competitors, we lost valuable time, and then valuable mileage keeping others from finding us. We had to play it cool since both teams were onsite. It turned out that we played it a little bit too cool and they found the fox first.
Tools Used: 2 meter rigs - 2; Space Shuttle - 1; Directional antennae- 0; Other antennae - >0 (actual type and number are classified); Custom Built receivers and attenuators - 0; Other secret weapons: (Classified - what was in that backpack?) Congrats to the winners and to all who found the fox.
From the Third Place Team, Dennis, KA4ATK and Darrell, KF4URC submitted by Dennis KA4ATK
Several weeks before the August meeting I received an email indicating something about a fox hunt at the next club meeting and that further information would be available on the club's web page. I procrastinated about checking out the information; but finally on the morning of the meeting, I finally checked into the club site to get the information. I immediately became enthusiastic about participating.
I gave Darrell, KF4URC, a call to see if he would be interested in participating. He said he didn't have any equipment or experience, but that he had heard about the hunt and it sounded interesting. I told him I had a couple things that I had used in past hunts, so we decided to give it a try. At the worst we just wouldn't find the fox.
Our fire power consisted of my standard mobile 2 meter rig, an attenuator that I built from an article in QST, and a Doppler dipole antenna that was designed by the Coast Guard Auxiliary for use in finding boats in distress (marine frequency 156.8 MHz). The latter two pieces of equipment I discovered later when searching for copies for Darrell are at least 15 years old. Gee, time flies, I thought it had just been about seven or eight years ago that I built them.
After checking in and receiving our instructions the hunt began. We were receiving less than a full strength reading on the mobile rig. We turned right on Maynard Road from the meeting site. Just about the time we got to Brown-Winn Funeral Home we had a full strength reading on the S meter. Great!! We went the right direction. We continued on.
When we got to the intersection of Maynard and Kildaire Farm, the signal strength dropped. We turned right on Kildaire Farm. Signal strength was up and down, so we turned right on Cornwall and still had flaky signal strength readings. We "guessed" the fox was at the Cary Mall, so we headed for Walnut Street and the mall.
Bad decision. Signal strength readings indicated we were wrong. What do we do now? We decided to head back out Maynard Road toward the funeral home where we had a strong signal. We stopped and took some measurements with the Doppler. Nothing conclusive, so we headed out Kildaire Farm to the left this time. Bingo! The signal was getting stronger. We kept going out Kildaire past Cary Parkway. Not far past the Parkway the signal began to fade. Time to turn around.
I don't remember our exact search from there, but we spent about 90% of our searching time within a quarter mile of the actual fox, mostly in the area of the shopping center parking lot around Winn Dixie. The Doppler readings in that area gave some good nulls (determined later), but I took them to be 180 degrees from the real fox.
After a fair amount of looking, we decided the fox couldn't be where we were looking, so we decided to check the parking lot on the other side of Kildare Farm Road. Bingo! The signal was off scale with full attenuation. Using the Doppler we finally managed to find the fox.
Although we were not first, we had a great time; and we did find the fox. Darrell said it was his first hunt, and that he thoroughly enjoyed it. He said he can hardly wait for the next one.
From the Fourth Place Team, Tom, KM4LB and Mike, K4ZMY. Submitted by Tom, KM4LB
Some Celebrate..........While Others Calibrate
"Team CCC" was comprised of Mike, K4ZMY and Tom, KM4LB. The CCC comes from the antenna mounted on the van. (see Fig 2 in AB4S's article.) Being somewhat more substantial and having more lethal area than a "Texas Bug Catcher" I dubbed the quad a "Carolina Crow Catcher."
In addition to the quad, our gear included two mobile rigs, two ht's, an active attenuator, the waveguide attenuator featured in last month's feedline, and two compact two meter yagi "walking sticks" - one with two elements, and one with three elements, and USGS maps of Cary. (Projects, including van mod will be on display at next meeting.)
In a planned move, we drove directly to the parking deck behind the Lawrence Building on Kildaire Farm Road (0.7 mile). From the upper level we took the first of our biangulation (more on this later) fixes. It pointed directly down KFR and bisected Hemlock Bluffs Park. I decided to take our next fix from behind the fire station near KFR and Tryon Road since it is a high spot and would take us in the direction of our first fix. We drove right past the fox at 1.4 miles.
DOH! the second fix told us we had passed the fox and it was somewhere back north up KFR. The lines from the two fixes crossed between McDonald's and LoneStar. NOTE: This 2.8 mile trip up and down KFR in itself would have lost first place for us based on Jeff's more direct drive to the fox. The post-mortem shows we made our biggest mistake by not taking a third fix from a point at right angles to the first two which where up and down KFR. We got ourselves too close to the water tower and buildings which were confusing because of multipath present.
Mike finally got a good fix using one of the walking sticks from the soccer field in front of the elementary school. It pointed us toward Winn Dixie. At this close a range, the quad was overloading the ICOM mobile rig. In desperation, sitting in the lot near Wendy's, I told Mike to try the waveguide attenuator on the quad. (We had tossed it in the "garbage can" earlier because of its poor performance out in the open when attached to an ht and walking stick - too much rf bypassing it.)
When Mike slid the waveguide open about half way, the signal just dropped off the meter. With the radio and the attenuator cocooned inside the van, the best path was thru the quad. Mike backed off the waveguide a bit and centered the s-meter. A few swipes of the quad told us "go west, go west." Two minutes later we drove up to the fox which was easier to find with a half-dozen hams lingering about!
In addition to stopping at "biangulation," another error was that we did not track signal while driving since this would have indicated to us that we passed it on the way to the second fix. Part of this problem was solved by putting the waveguide attenutator in the quad feedline since without it, the quad was overloaded and was not useful at close range.
We learned a lot about our new toys and we also learned not to leave the van to track on foot (water tower, and soccer field) without any data to support that decision (hunch hunting). We shouldn't have backed ourselves up to buildings and the water tower which were causing more multipath signals. Another problem was not calibrating the quad to the van. A week later I got some interesting results from testing the "boresight" of the quad.
The fixes we took on the hunt crossed a block north of the fox - somewhere between Mcdonald's and Lonestar. This indicates that the van detunes the quad "to the right" and the tests proved this to be true. Sighting on the .15 tower I found an increase of 5 degrees in the boresight of the quad versus the true path to the tower. This offset was duplicated when I went to the construction area behind Lowes and set the fox out and took readings on it.
Now the real interesting discovery...I tested both off the front of the van, and with the van 90 degrees to the target (hoping for no error off the side - no joy - still indicating off to the right.) What i did find tho is that off the front of the van, you have to turn the quad 9 to 11 degrees right, or 9-11 degrees left to get to a null, that is, zero bars on the s-meter. This indicates a beamwidth of about 22 degrees.
When I turned the van sideways to the target, and kept the same setting on the waveguide attenuator, I had to turn the quad 20 degrees right, or 20 degrees left before the signal dropped off the scale. So, off the front, you have to turn the quad just past each headlight to hit a null, yet when turned sideways, you have to go front fender to back fender to hit a null. I suspect the van is just like a boulder on the beach with waves crashing against it. The rf hits the front or side of the van and scatters proportionatly. Since the area off the front is less than the side, you have to travel less of a distance to get to a null.
And the next Foxhunt is.....
Jeff and Charles expect to have the next fox ready to go "before Thanksgiving," so don't let your gear get out of sight. Jeff's QTH is up in Youngsville, and Charles' down in Johnston County. That could make for an interesting field of play! It will probably be on a weekend in order to attract more teams.