Make your own free website on Tripod.com
Clif's Ham Radio Page

Welcome to Clif's ham radio connection. On this page you'll find links to other interesting sites. It is not my intention to create the end all page with links to everywhere but I've included a few of the ones that I think are most pertinent.

My particular area of interest is in high frequency (HF) antennas in less than optimal conditions. Most of the available programs used to analyze antennas today assume that the antenna is mounted in free space or mounted a uniform distance above ground - conditions that unfortunately many hams can get nowhere near achieving. Since the software tools are somewhat limited in what can be simulated I'm instead looking for the apartment dwellers, condo owners and other restricted antenna users with any experience. Your experience level is not important - what you did and what the results were are more important. It doesn't matter if what you tried didn't work, just let the rest of us know so we might learn from your experience. I'm collecting data - not to analyze but rather to show empirically what works and what doesn't. Send me all your details, in particular try to provide the following information:

I'll make the data available here as case studies. I've included the results of my own experiences to give you an idea. Got comments or questions? Ideas of how to make this site better? Email me!
As more data becomes available, the format of this page may change, however it will remain the entry point into the database with the same name and location so go ahead and bookmark it.

Summary of experience with restricted space antennas
First and foremost hams faced with restrictive antenna constraints should not lose faith. You still can operate sucessfully although you will never be able to out-slug the hams running linears into beams mounted high up on towers. If you build a hidden outdoor antenna you will probably be limited to 100 watts or less due to the wire sizes and insulator types. If the antenna is mounted indoors, your power will still be restricted due to health hazards to yourself or other family members (arcing or RF energy) or due to interference with televisions, computers, VCRs, telephones, etc. However the QRP hams continue to show us that QSOs can and do happen with regularity at low power outputs. In general you should strive to build an antenna as high and as close to full size as your situation allows. If elements need to be bent to fit the space thats ok - just try not to have them double back on themselves. An antenna tuner is a must have item with almost any antenna you will build. Almost anything metal can be made to radiate RF energy so don't despair! If you meet with sucess, drop me some email so we can share it with others. Some other common approaches are the flagpole vertical, the magnetic loop and slinky dipole. Another approach I want to try is to build a St. Louis Vertical which is a portable antenna that works 10m to 40m and only erect it when I'm on the air.

Case 1: 10m dipole in attic

Antenna type
Full size dipole made with #24 gauge magnet wire and ceramic insulators. Oriented approximately NNW by SSE. Actual elevation above ground was approximately 25 to 30 feet.
Structure
Two and a half story condominium unit. Shack was in upper level with the antenna mounted in the attic using cord to mount the antenna between rafters. Structure was wood frame with a stucco exterior and a composite shingle roof. Also under one half of the dipole was a forced air furnace made of galvanized steel. This heater was about 2.5 feet below the wire of the dipole. Shack was located in Southern California.
Rig Details
Icom IC725 running average of 50 watts. Coupled to antenna through RG58/U coax. Used MFJ-941E tuner to match rig to antenna.
Performance Summary
When the 10m band opened, 50 watts and my attic dipole did quite well. Most signal reports were 55 to 59. Contacts were made to Indiana, Alabama, Louisiana, Texas, Wisconsin, Kansas, Minnesota, Mississippi, Pennslyvania, North Carolina, New York, Rhode Island, Hawaii plus a few other states and even Japan!
Comments
This antenna may have done well since it was in a wood structure and the actual antenna height above ground was greater than a half wavelength. The contacts appeared consistent with the orientation of the antenna, that is most of the contact occured broadside to the antenna.

Case 2: 40m twin lead Marconi in attic

Antenna type
This antenna was a twin lead Marconi based on information found in William Orr's Radio Handbook. This antenna was also fed with RG-58/U coax. In addition, a half wavelength counterpoise was attached to the coax shield/antenna junction to provide an RF ground.
Structure
This antenna was also mounted in the same attic as case 1. The twin lead was snaked around the perimeter of the attic and held in place by attaching it to the studs with cable ties. The twin lead could not be laid out in a straight line instead it was routed in a shape like a question mark where the bottom of the question mark was the feed point. The first section was about 20 feet followed by a 90 degree bend and the next 10 feet followed by another 90 degree bend and the final 3 or 4 feet. The first section was oriented roughly E-W, the second section N-S and the third section was again E-W. The counterpoise was snaked in the other direction in a similar shape with the first section of about 25' going N-S, and the remainder going E-W.
Rig Details
Same as Case 1.
Performance Summary
As expected, this antenna didn't perform like a free space 1/4 wave vertical. It took time but the MFJ tuner would get a good match to the transmitter. Normal power used was 50 watts. Contacts ranged all around the western United States with the majority in Oregon, Washington and Northern California. There were also contacts made in Idaho, Utah, Montana, Colorado, Nevada, Alaska, British Columbia and Texas.
Comments
This antenna was used to primarily work 40m CW. On occasion it was used of 15m CW also. Signal reports were average with R's of 4 to 5, S's from 3 to 9 and T's of 9. There were very few reports of 599. The signal was getting out but not very well. Almost all the contacts were broadside to the longest section of the twinlead.

Case 3: Triband inverted V dipole under the eaves

Antenna type
This antenna was constructed as a 40m dipole and a 10m dipole with a common feedpoint. The 10m elements are built using #24 gauge magnet wire and ceramic insulators. The 40m elements are built using #18 gauge hookup wire. The apex of the inverted V is at the high point of the roofline, approximately 18 to 19' above ground. The 10m elements slant downward about 30 degrees below horizontal and remain spaced about 14 inches from the stucco surface of the wall. The 40m elements are secured under the eaves and extend about 30 feet from the apex before reaching the corners of the house where they both make 90 degree bends and continue under the eaves. At this point, the elements are only about 8 feet above ground. The major portion of both antennas are oriented N-S.
Structure
The house is a wood frame, stucco exterior, single story dwelling with a concrete tile roof. The eaves extend about 16 inches beyond the walls of the house. The house is located in Southern California.
Rig Details
Same as Case 1.
Performance Summary
So far it appears that the proximity to the structure make the 40m antenna appear electrically longer than it is physically. Only one QSO has been completed so far and that was with a station in WA. RST report was 469 but WA is off the "end" of the major axis of this antenna. At this time (7/10/97) no contacts on 10m have been completed but the band still appears dead.
Comments
With only one QSO completed, the jury is still out on this antenna. Will update this page as more as information becomes available.

Case 4: 10m dipole in attic

Antenna type
Full size dipole made with #24 gauge magnet wire and ceramic insulators. Oriented approximately NNW by SSE. Actual elevation above ground was approximately 15 to 18 feet. Dipole was not perfectly horizontal, instead it was oriented more like an inverted V with about a 15 to 20 degree slope.
Structure
Single story, single family house. Wood frame, stucco exterior walls with a concrete tile roof. Shack was located in Southern California.
Rig Details
Icom IC725 running average of 50 watts. Coupled to antenna through RG58/U coax. Used MFJ-941E tuner to match rig to antenna.
Performance Summary
No contacts were made. Did manage to hear two or three other stations but all attempts to reach them were unsucessful. Wasn't able to determine how much power the other stations were running or the type of setup used. Also used the antenna as a receive only on 40m, this appears to have worked but without another outdoor antenna that could be switched in, no comparative measurements could be made.
Comments
Data for this case is inconclusive. Band conditions on 10m were very poor so there may not have been any stations there to begin with. Theorized that the concrete tiles could have been interfering with the radiation of energy from the antenna. The antenna has since been relocated outside the house under the eaves - see case 3.

Links to other ham related sites
FCC Home page
FCC Downloadable forms Includes form 610
ARRL Home page
Near realtime MUF map actual color map updated every 5 minutes
AC6V Ham Radio DX Reference Guide Tons of great links
KB9JJA Ham Radio check out fun stuff
American QRP Home page St Louis vertical information
Details on Slinky antennas



This page has been visited times.