Faulkner County Amateur Radio Club W5AUU - minutes for the meeting, Tuesday, March 10, 2009
Meeting was called to order at 6:30 pm by President Frankie Parks
A roster of members was circulated. The following checked as present:
Kelly Boswell KA5MGL
George Carroll N5GC V.P
David Doty N5XF
Lynette Dowdy KD5QMD
Kayla Dowdy KE5JYX
Philip Doyle KC5BAY
Jim Elliott W5JNE
Bill Fill KD5IC
Dora Anna Fill NI5D
Jim Grinder N5TSG
Bob Hambuchen N5OMW
Randy Harrington N5RYG
Gary Hawkins Sr. KD5YIX
Gerald Hogue AE5GH
Greg Hutchinson KD5WSI
Stefan Johnson KE5YBN
Wayne Johnston KD4TA Sec/Treas
Brian Kessler N1WNC
Marlene Kessler KE5HQU
Glenn King N5GK
Kenneth Leo W5HXK
Warren Lindgren KE5TT
Eric Martin N5EMX
Stuart Nelson KD5LBE
John Nordlund AD5FU
Frankie Parks K5FRP Pres.
Bill Thomas K9BT
David Turner KD5JKX
Roger Williamson N5QNA
Kathy Williamson KB5RMY
Treasurer Report
The FCARC currently has $2,918.93 in the bank, plus $10.00 in dues collected at the current meeting. No outstanding bills as George Carrol donated the cost of the table at the Russellville Hamfest. We have 53 paid members at this time.
Old Business:
Financial report from the Russellville Hamfest
It was a success for the FCARC finances and our storage guru Glenn King. At the inside booth from 8-9 am eight sales, 9-10 am one sale, 10 -11 am three sales and nine sales in last 40 minutes for a total of $149.00 from the rented table space. The outside sales from the trailer parked outside the gym totaled $555.00, most of that items that had been stored at Glenn King's shop and garage for months or years. This was the remnants of the third estate that Glenn has stored on behalf of the FCARC.
Toad Suck Days Special Events Station
The members previously voted to have a Toad Suck Days special event station and Frankie Parks was able to submit the event for the ARRL QST special event announcements. It should be in the April issue of QST. Toad Suck Days will be 1,2 & 3 May 2009. On Saturday May 2 fro 8:00 a.m. To 12:00 noon the FCARC will be on the air at 14.260 Mhz or 7.260 Mhz.
New Business:
Iron Mountain Triathlon -- June 6 and 7, 2009
Updates to follow after a meeting about the event on Thursday.
Field Day
The FCARC will need a new chairperson for the Field Day event. Wayne Johnston has done a terrific job for the past three years, but he would like to hand over the reins for that event. In the absence of a volunteer to chair the committee, Frankie Parks will contact several members (or draw names from a hat) in an attempt to persuade them to take on the task. Gary Hawkins Jr and Sr were nominated from the floor, but Sr was not present and Jr would have to be persuaded. June 27 and 28.
Central Arkansas Hamfest
George Carrol called President Frankie Parks just before the meeting started and wanted to raise the issue of FCARC particpating with other clubs in a Central Arkansas Hamfest. This would be a collaboration between CAUHF, and other clubs in Cabot, Russellville, Hot Springs, Morilleton -- in other words a real nice hamfest to be held about September 26, 2009. The first choice of places to hold the event would be the Maumelle Jr High gym. The FCARC members voted to participate in such an event. The FCARC representative to meet on a committee about the event would be George Carroll -- voted by the members. The plan is for this hamfest to be a big event with next year to meet at the convention center at the Metroplex facility.
Hospitals All Hazards Exercise on Wednesday May 20, 2009
John Nordlund announced the state wide event, and noted that all of the communications systems and all backup communications systems would be used during the exercise. Some of the hospitals near Conway might need hams to supplement their operations. John has a hard time coordinating participation because he is being treated as a player. This exercise will involve every hospital in the state on that same date.
Test Session -- followed the regular meeting.
Main Program:
Wire Beam Antennas -- Wayne Johnston KD4TA circulated a photo of the collection of wire antennas that he has accumulated over the years -- wire and "cheap" or so he thought when he got started. The lesson learned might be to buy a really good antenna and stick it up high enough that you don't have to constantly experiment.
Why do we fool with wire antennas? Because they are good and easy. Glenn King swears by a tuned dipole as being almost as good as any other antenna provided you have the location and supports to put it high enough. For example, a 20m antenna is only about 32 ft. long -- but it really occupies all the space required by supports and guy lines. If you do not have two strategically placed telephone poles, you have to use trees that blow in the wind and allow the center feed line to sag. Antennas should not be connected directly to swaying trees as metal fatigue eventually will claim the antenna. Support it instead by a weighted pulley system that allows the dipole to remain fairly steady. The downside is the amount of rope and pulleys.
An alternative is use an inverted V for the dipole with a tree supporting the center. Because the angle of the inverted V cannot be too acute, the actual footprint of the 32ft 20m antenna is more like 90ft. At that point the idea of a wire antenna become more favorable.
Adding a director and a reflector that are at supported at least 10ft from the dipole with PVC poles results in antenna that is 32ft x 20 ft (not including any supports). Attaching a wiring harness to the PVC stretches out the wire beam in a flat horizontal orientation (provided there is adequate tension on the dipole to support the feed line). But one is still left with attaching the entire array to whatever trees there are in the neighborhood by means of rope and pulley systems. Converting the entire wire beam to an inverted V results in a really good antenna that can be rotated, provided you are willing to untie and retie each of the eight or more supporting guy lines for the entire mess to rotate it about 5 degrees. These are good antennas-- one was used to contact Rodriquez Island (north of Madagascar) in the Indian Ocean on ½ watt during a different sunspot cycle.
The easiest wire beam alternative is the fishing pole dipole that is only 32 ft across with the antenna hidden inside fishing poles. But it is still a dipole.
The next alternative is a Moxon antenna that is 9 ft wide and 25 ft long on a "X" support base. The antenna weighs only five pounds for a single frequency. This antenna was developed in the last 20 years by Les Moxon. He took a dipole antenna and bent the ends inward and bent the reflector inward. Visualize two squared off Cs facing each other with the distance between them as a critical dimension. The downside of the Moxon design is the support requirement -- a center hub and PVC or fishing poles to support the antenna wire array. The wire antenna is compact but the support system can be complicated.
The Hex Beam antenna is only 19 ft across in the shape of reflective "W"
A viable alternative is the C Pole antenna -- a vertical antenna that does not require all the extensive support structure.
One drawback of most of the wire beam antennas is their narrow bandwidth. But the wire antenna in the March QST is a broadband Hex Beam that was developed in 2008.
The purpose of the first part of the antenna program was to demonstrate how we have progressed (?) from the simple and efficient dipole to more and more complicated support systems and antenna designs in pursuit of a better antenna.
Low Profile Operations and Rapid Deployment Antenna Systems by John Nordlund
The second part of the wire antenna program was by John Nordlund, who talked about antennas that were quick to put up and use, and might even be invisible to the casual observer.
The whole idea of underground antennas caught John's attention when he was in high school. The 11 meter band was the craze, and he played CB and short wave listener. He buried a full 5/8 wave CB base station antenna upside down in the ground, just to see what would happen. He was told that it would not work, but he used it for four years and no one could tell where it was located.
The soil of the earth is not radio reflective -- it is a high loss dielectric medium. The reflective characteristics that we take advantage of with regular antennas is merely the difference
Just like a sheet of glass, some of the light is reflected because of the
In this case, we need to think of an antenna as a transducer -- a device that couples energy from one medium to another. In the usual antenna we are transferring RF energy from wire to space. The coupling can be either electric or magnetic. A conventional dipole coupled electrically and the wave moves along the antenna. A loop antenna tends to couple magnetically to the magnetic component of the RF wave causing electrical waves to be induces in the wire. Antennas that are close or on the ground tend to react with the magnetic component of the RF energy.
In dealing with antennas at or near the ground, the dielectric relationship is different -- hence the length will vary with the exact location of the antenna. An antenna buried in the soil will be shorter that the same antenna mounted above ground. Expect a very low velocity factor -- 40 to 25 percent if typical. This means that antenna for 80 M (130 ft long) can be half or one quarter of that size. This can be useful with a very small yard. Most antenna experimenters give up rather than attempting to shorten the antenna dramatically.
Remember that an antenna buried only 8 in. under the ground will have attenuation of about 16db over a similar antenna mounted one third wavelength above ground. The attenuation will increase with depth and will vary with weather conditions and soil conductivity.
With antenna restrictions we have to be inventive. A dipole can be bent into unusual shapes in the attic (provided you have access) but transmissions may interfere with other electrical devices.
John carries all his wire antennas in a go-bag for quick and easy access. His G5RV antenna is from Antennas and More (www.antennasmore.com). His 40 m antenna has a 15 ft. matching section. If no vertical supports are available, then the antenna can be attached to a ordinary wood fence with the normal matching section coming away at a right angle because it need not be vertical! In such a configuration it functions as an NVIS antenna with good propagation within 300 miles. With a tuner, the antenna will work on all HF bands.
Ground Proximity Antennas. These were completely buried or were emplaced in concrete "Jersey Barrier" like you see on the freeway for use by Department of Defense organizations. For example, Hill AFB had the antenna in a parking lot with the Jersey Barriers used as dividers.
The developer, Eyring Research, developed a tactical version that has applications for ham operators involving insulated wire that was placed on short supports and on the ground. Feedpoint impedence rises as the antenna is placed closer to the soil. The permanently emplaced versions had drained gravel beds at the center. The result is a vertically polarized antenna that is only six inches off the ground!
With a low take off angle the antenna works well, although the signal is antennuated. These deficiencies can be cured with more power on transmit or a pre-amp on receive.
John's real world triumph with this type antenna happened in Orem, Utah for a friend who lived downstairs in an apartment complex and had no place for an antenna. A flower bed that ran the entire length of the building game them the opportunity to put a ground proximity antenna built inside the plastic tubing intended for irrigating the flower beds. One row of sprinkler heads was attached to ¼ inch poly pipe mounted on plastic stakes that ran most of the length of the flower bed iand contained the antenna. Another similar row of heads located nearby had the actual water system for the flowers. Once a day the sprinklers sprayed water, but the line of sprinklers about two feet closer to the sidewalk never worked because it contained the HF radio antenna inside the poly pipe. It was used at power levels up to 900 watts. RF safety power levels were not addressed at that time!
The Eyring patent application is available on line in a 90 page pdf file that explains how the antenna works. It also works well as an off-center fed dipole, with about the same 1/3 to 2/3 split like a Windom antenna. This allowed the feed line to be more closely matched to the antenna at a high impedence point like the Windom.
Remember with these antennas that the impedence rises with proximity to ground, the matching network has to be different (12:1 or so), some experimentation will be required for the particular location used, and the signals will be attenuated significantly.
John had the best results when the antenna was configured so that it operated as a current controlled dipole. He inserted capacitors in series with the wires so that the reactance was balanced out. This means that the antenna will be double the length of a standard dipole antenna. The antenna was low noise and very broad banded. He did not experience static or noise with the antenna. One of his antennas built this way and wrapped around the yard did not produce noise even though there were lightening storms in the area. He was talking to Japan and had no noise even with a nearby lightening strike.
Q & A. The tactical Eyring antenna was 120 ft long and would handle any HF or VHF frequency. The Army tested the antenna, but went with other cheaper designs. Eyring offered the antennas in a commercial version, but as they were trying to recover development costs, it cost too much.
John thinks the Eyring concept has value for deployed antennas when there are no standing trees in a disaster area, and PVC poles are not available.
During the development of the antenna it was a secret system. John was involved in the testing and development of the Eyring antenna by taking reading from a field strength meter when told to do so via radio.
The antenna cannot be modeled in NEC programs, because of the different characteristics and assumptions about the area under the surface where RF energy is absorbed and slowed by organics components in the soil.
These antennas close to the ground change with different conditions -- rain, moisture content in the wood fence, etc make the antenna different on different days. Hence we put wire antennas at least 1/3 wavelength high to avoid these changes.
Another friend of his used the gutters (over 400 ft in length) as a random length loop.
The military version of these antennas had eight to ten in parallel -- every row in the Hill AFB parking lot had a set of Jersey Barriers for ten rows of cars -- i.e. Ten Eyring antennas in parallel.