ANTENNA DIAMETER

[carlvenorden]

Actually I mispoke when I mentioned the top hat (in a part 15 installation) mirroring a counterpoise. That is not what I was getting at, and I'm sorry.

The actual top hat I built looked more like a peace sign, or a "Y" than anything else and seemed to more directionalize the signal. I can't really prove it did, just that my observations driving the signal seemed to indicate that was so.

I don't have any reports on this one handy, but I also built one with a top hat composed of probably 100 copper wires, all about a foot long hanging from the top of the antenna.
Actually it was an ugly mess, looked like a skinny guy with a bad hairdo.
But I tried this and liked the results personally.

A top hat can indeed improve the signal.

 

[radiopilot]

Actually I mispoke when I mentioned the top hat (in a part 15 installation) mirroring a counterpoise. That is not what I was getting at, and I'm sorry.

The actual top hat I built looked more like a peace sign, or a "Y" than anything else and seemed to more directionalize the signal. I can't really prove it did, just that my observations driving the signal seemed to indicate that was so.

I don't have any reports on this one handy, but I also built one with a top hat composed of probably 100 copper wires, all about a foot long hanging from the top of the antenna.
Actually it was an ugly mess, looked like a skinny guy with a bad hairdo.
But I tried this and liked the results personally.

A top hat can indeed improve the signal.

Carl

I'm glad you got back to me... anyway I'm waiting on getting my antenna retrofitted with a top hat as described earlier, it will be almost the same or larger that the one described.

Here's my plan:

2-3 inch copper pipe (larger if I can find it) 3-meters tall

36 inch wire mesh parabola satelite antenna (fiberglass would be best, if not a copper skeleton with copper mesh)

Loading coil to be 6-10 inch dia. using #12 gage copper wire or copper plumbing hose (1/8" - 1/4") depending on how many turns to get the required inductance.

The parabola antenna will be brazed onto the copper pipe and brazed onto the 2-3" copper pipe will be 3 each bracket/eyelets so that insulated guy wires can support the antenna for high wnds.

The loading coil form will be glass and the coil formed on this and either the glass removed and used as a free standing coil or keep the glass shape in and epoxy the coil in place... Instead of using taps for the coil, I will sand off the copper as clean as I can and use a 'wiper' to get as best a signal on my meter berore I solder the transmitter wire in place

This should surely work much better than what I have now... might not be as 'pretty' but no one can see my antenna at the location I have it placed.

Radiopilot

 

[Black_Shire]

Actually I mispoke when I mentioned the top hat (in a part 15 installation) mirroring a counterpoise. That is not what I was getting at, and I'm sorry.

The actual top hat I built looked more like a peace sign, or a "Y" than anything else and seemed to more directionalize the signal. I can't really prove it did, just that my observations driving the signal seemed to indicate that was so.

I don't have any reports on this one handy, but I also built one with a top hat composed of probably 100 copper wires, all about a foot long hanging from the top of the antenna.
Actually it was an ugly mess, looked like a skinny guy with a bad hairdo.
But I tried this and liked the results personally.

A top hat can indeed improve the signal.

If you're looking at designing these for indoor installation (say, inside a closet), the top hat can be a square or circular sheet of aluminum foil affixed to the ceiling, with the top of the wire or copper pipe antenna connected to its center.

The top hat can be attached to the ceiling using thumbtacks or double-sided, self-adhesive tape. Speaking of tape, the self-adhesive copper tape with electrically-conductive adhesive (often used for shielding applications in audio work) would be perfect for making the connection to the foil top hat, as wire can be soldered to it.

For that matter, the ground screen directly under the antenna base could also be made of aluminum foil, with ground radial wires (if you have the space for them indoors) connected to it using the self-adhesive copper tape. Indoors, we can get away with using more fragile and less weather-resistant materials for building antennas and ground systems.


-- Black Shire

 

[Black_Shire]

Actually I mispoke when I mentioned the top hat (in a part 15 installation) mirroring a counterpoise. That is not what I was getting at, and I'm sorry.

The actual top hat I built looked more like a peace sign, or a "Y" than anything else and seemed to more directionalize the signal. I can't really prove it did, just that my observations driving the signal seemed to indicate that was so.

I don't have any reports on this one handy, but I also built one with a top hat composed of probably 100 copper wires, all about a foot long hanging from the top of the antenna.
Actually it was an ugly mess, looked like a skinny guy with a bad hairdo.
But I tried this and liked the results personally.

A top hat can indeed improve the signal.

Carl

I'm glad you got back to me... anyway I'm waiting on getting my antenna retrofitted with a top hat as described earlier, it will be almost the same or larger that the one described.

Here's my plan:

2-3 inch copper pipe (larger if I can find it) 3-meters tall

36 inch wire mesh parabola satelite antenna (fiberglass would be best, if not a copper skeleton with copper mesh)

Loading coil to be 6-10 inch dia. using #12 gage copper wire or copper plumbing hose (1/8" - 1/4") depending on how many turns to get the required inductance.

The parabola antenna will be brazed onto the copper pipe and brazed onto the 2-3" copper pipe will be 3 each bracket/eyelets so that insulated guy wires can support the antenna for high wnds.

The loading coil form will be glass and the coil formed on this and either the glass removed and used as a free standing coil or keep the glass shape in and epoxy the coil in place... Instead of using taps for the coil, I will sand off the copper as clean as I can and use a 'wiper' to get as best a signal on my meter berore I solder the transmitter wire in place

This should surely work much better than what I have now... might not be as 'pretty' but no one can see my antenna at the location I have it placed.

Radiopilot

Just one thing...on the NC MedFER beacon, the dish-turned-top hat was mounted atop the antenna facing downwards (the "bowl emptied," so to speak). The downward-curving dish shielded the very uppermost part of the antenna and blocked the signal coming from it. That is why towers that use the uppermost guy wires for top-loading don't have them too long (you'll see them electrically "broken" using insulators about 1/5 - 1/3 way down), so that the sloping top-loading wires don't shield too much of the signal from the tower.

With our stubby 3 meter antennas, it pays to use every centimeter we can to radiate the signal. If I used a dish for the top hat I'd mount it atop the antenna facing upwards, so that it wouldn't shield any part of the vertical radiator. (Many top-hatted mast and tower NDB antennas also have their top hat elements angled slightly upwards for the same reason.)

Two or three small drainage holes drilled through the dish a few inches out from the antenna mounting point would keep it from turning into a bird bath every time it rained.


-- Black Shire

 

[kc8gpd]

I know this would not have an effect on f/s, but what would making a stranded coper mast out of 3m long 1/4 inch copper tubing tied together in parralel making a 3" dia. x 3m mast have on the bandwidth?

I'm trying to come up with a part 15 compliant setup that has wide enough bandwidth to work with Chris Cuff's C-QuAM transmitters.

 

[Black_Shire]

I know this would not have an effect on f/s, but what would making a stranded coper mast out of 3m long 1/4 inch copper tubing tied together in parralel making a 3" dia. x 3m mast have on the bandwidth?

I'm trying to come up with a part 15 compliant setup that has wide enough bandwidth to work with Chris Cuff's C-QuAM transmitters.

That would indeed increase the antenna's bandwidth. That can also be done using a 3 meter tall vertical "wire cage" antenna.

A few Long Wave aviation Non-Directional Beacons (NDBs) use this "wire cage" type of antenna. You can see several photographs of one on this web site: www.w3eee.com (click on "NDBs" on the left-hand side of the first screen-page, then click on "RD - 356 kHz - Reading, PA" near the bottom of the "NDBs" page).

There are also pictures of other US NDBs (as well as Canadian and UK NDBs) on this web site. Their antennas range from top-loaded AM broadcasting-type towers (using the uppermost set of guy wires for top loading) to short towers & tubular masts with 6 or 8 top loading elements to wire "Tee" antennas. Some of the "Tee" antennas are very small (in terms of the wavelength), yet they radiate adequately well for their intended application.


-- Black Shire

 

[carlvenorden]

Another one of my experiments, in response to the Reverend, was my idea of a part 15 radiator built like a folded unipole. I started out with a verticle, a similar tophat to the one I had previously built (with a copy of that toward the bottom) and ran copper wire vertically between these posts. It looked like a folded unipole, but I found no real increase in signal strength.
Next, I removed the wires and replaced them with copper tube (thats a lot of copper, and a pretty heavy antenna). This was much more spectacular, and did a great job inside an alluminum sided house. It was also a "huge" installation, but it proves that it works.

 

[phatdaddy]

Another idea is to go to a hardware or home improvement store and get enough 4" aluminum dryer vent pipe to stack 10 feet high. My "stealth" dryer vent antenna is working nicely considering it is an attic antenna. If this same antenna could be ground mounted over a good ground system it should give good bandwidth and good performance for a cheap price. A coating of earth-tone paint would render it nearly invisible in the average back yard.

 

[raymond_shaw]

Doesn't FCC rule Part 15.203(re: using only an antenna certified with the device) mean use of these type of antennas is illegal and won't pass FCC inspection?

 

[radiopilot]

Doesn't FCC rule Part 15.203(re: using only an antenna certified with the device) mean use of these type of antennas is illegal and won't pass FCC inspection?

Only for FCC Certified devices...

If it's a kit, or homebrewed, or under Part 15.219... no need as long as it's 3 meters or less... read the Part 15 rules again. Even the Rangemaster needs to use the 3 meter CB whip antenna as that's the antenna used during certification but some users do use other antennas instead of the whip.

Radiopilot

 

[raymond_shaw]

Doesn't FCC rule Part 15.203(re: using only an antenna certified with the device) mean use of these type of antennas is illegal and won't pass FCC inspection?

Only for FCC Certified devices...

If it's a kit, or homebrewed, or under Part 15.219... no need as long as it's 3 meters or less... read the Part 15 rules again. Even the Rangemaster needs to use the 3 meter CB whip antenna as that's the antenna used during certification but some users do use other antennas instead of the whip.

So kits and homebrewed can do this and Rangemaster cannot under Part 15.219? Since this type of antenna system seems to get incredible results, wouldn't that put Rangemaster owners(and owners of other FCC certified xmtrs) at a disadvantage? After all, the aim is to squeeze out the largest coverage area.

 

[radiopilot]

Doesn't FCC rule Part 15.203(re: using only an antenna certified with the device) mean use of these type of antennas is illegal and won't pass FCC inspection?

Only for FCC Certified devices...

If it's a kit, or homebrewed, or under Part 15.219... no need as long as it's 3 meters or less... read the Part 15 rules again. Even the Rangemaster needs to use the 3 meter CB whip antenna as that's the antenna used during certification but some users do use other antennas instead of the whip.

So kits and homebrewed can do this and Rangemaster cannot under Part 15.219?   Since this type of antenna system seems to get incredible results, wouldn't that put Rangemaster owners(and owners of other FCC certified xmtrs) at a disadvantage?  After all, the aim is to squeeze out the largest coverage area.

                      TITLE 47--TELECOMMUNICATION



              CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION



PART 15_RADIO FREQUENCY DEVICES--Table of Contents



                    Subpart C_Intentional Radiators



Sec.  15.203  Antenna requirement.



    An intentional radiator shall be designed to ensure that no antenna

other than that furnished by the responsible party shall be used with

the device.



[[Page 881]]



The use of a permanently attached antenna or of an antenna that uses a

unique coupling to the intentional radiator shall be considered

sufficient to comply with the provisions of this section. The

manufacturer may design the unit so that a broken antenna can be

replaced by the user, but the use of a standard antenna jack or

electrical connector is prohibited. This requirement does not apply to

carrier current devices or to devices operated under the provisions of

Sec.  15.211, Sec.  15.213, Sec.  15.217, Sec.  15.219, or Sec.  15.221.

Further, this requirement does not apply to intentional radiators that

must be professionally installed, such as perimeter protection systems

and some field disturbance sensors, or to other intentional radiators

which, in accordance with Sec.  15.31(d), must be measured at the

installation site. However, the installer shall be responsible for

ensuring that the proper antenna is employed so that the limits in this

part are not exceeded.



[54 FR 17714, Apr. 25, 1989, as amended at 55 FR 28762, July 13, 1990]

If you go to each Section of these subparts: Sec.  15.211, Sec.  15.213, Sec.  15.217, Sec.  15.219, or Sec.  15.221.,
You will see that as long as the transmitter does not have a 'unique antenna' attachment such as the Rangemaster has which uniquely uses the CB Whip antenna as it was FCC tested and maybe Kieth Hamilton of Rangemaster can chime in on... that CB whip antenna must be used and if an FCC Agent were to inspect the Rangemaster installation it would probably require that antenna and anything else may void the FCC certification.

The section of 15.219 is what most homebrew, or kits would use and any antenna arrangement can be used so long as the 3 meter rule is followed.

Yeah I agree it does put these certified units at a disadvantage but that is the price they paid when they got the unit certified.

Some are suggesting using the 3 meter copper tube antenna and loading coil, although I don't see any advantage since the Rangemaster already uses a coil built in... who knows it may work and get great signal coverage.

Radiopilot