Dipole antenna directly on the roof?

[tuscaroradave]

I am considering the purchase of an RCI 2990 CB base radio but where I live there are no antennas allowed so I am considering the purchase of a dipole antenna to lay or attach directly to the shingled roof of my 28' wide doublewide mobile home. My question is whether this will work just laid derectly on the shingles or does the dipole antenna have to be elevated to work. I am a total newbie to this stuff and am thinking of just getting the dipole, tacking it to the roof and hooking the coax between it and the radio. Would this dipole antenna need to be grounded? Sorry if these are stupid questions but I don't have a clue about anything radio related and thought this may be a good place to start.

Thanks in advance for any suggestions or advice. TD

 

[SCPD]

I bought a homebrew 11 meter dipole off of a good guy on ebay, works great.

As for your scenario, I would suggest trying to hoist your wire dipole up a tree, or maybe look into different antennas. If you have the money, i'd buy an Antron 99. Its about 17 feet tall, but can be used on the 11 meter or 10 meter band.

Maybe even making a dipole out of two fiberglass antennas. Easy and you would be able to rotate them above your house.

I'm really into CB's. What base station did you buy?

 

[VA3XDJ]

I suspect installing a dipole horizontally above your roof will yield any positive results.

Most likely end up with high SWR, a lot of TVI/RFI and poor signal reflection and penetration.

I would try using a PVC or wood pole and install it vertically away from any metals.

I would suggest maybe in a tree but I haven't tested it so its at your own risk!

 

[VA3XDJ]

Or maybe disguise it as a clothes line?

Since most CB uses vertical polarization and SSB uses horizontal you might be limited in what stations you can work depending on your setup.

Also, depending on how long you transmit and how much power you're putting out you might be exposing yourself to dangerous levels of RF.

 

[tuscaroradave]

I bought a homebrew 11 meter dipole off of a good guy on ebay, works great.

As for your scenario, I would suggest trying to hoist your wire dipole up a tree, or maybe look into different antennas. If you have the money, i'd buy an Antron 99. Its about 17 feet tall, but can be used on the 11 meter or 10 meter band.

Maybe even making a dipole out of two fiberglass antennas. Easy and you would be able to rotate them above your house.

I'm really into CB's. What base station did you buy?

Thanks for the reply, I used to have an Antron 99 with a radio I had years ago. Whatever I do go with I need it to be either a portable or temporary setup that I could easily mount just when I use the radio or something that can not be seen as the park I live in doesn't want antennas sticking above the houses.

I think I'm going to buy this Ranger 2990 this coming weekend.

I suspect installing a dipole horizontally above your roof will yield any positive results.

Most likely end up with high SWR, a lot of TVI/RFI and poor signal reflection and penetration.

I would try using a PVC or wood pole and install it vertically away from any metals.

I would suggest maybe in a tree but I haven't tested it so its at your own risk!

I was really thinking all of the above (except for the tree thing) but hoping that there would be an easy way to do this and still get some satisfactory results. I certainly don't want to cause any annoyances to the neighbors with TV interference. I wish I had a tree out there but a no go there.

Or maybe disguise it as a clothes line?

Since most CB uses vertical polarization and SSB uses horizontal you might be limited in what stations you can work depending on your setup.

Also, depending on how long you transmit and how much power you're putting out you might be exposing yourself to dangerous levels of RF.

I like the clothes line Idea. I don't need to go giving myself or anyone else cancer from high levels of RF. I have to walk around the house and come up with something creative.

Thanks again for the ideas guys.

 

[kb2vxa]

Your idea may work, barely. Best case scenario is a horizontally polarized figure 8 pattern broadside to the antenna and low to the ground you just won't "get out" very well. Since you can't get it up high to begin with you may consider the classic stealth approach, put a vertical that doesn't have horizontal radials (your choice) inside a PVC pipe and put a flag on it.

 

[VA3XDJ]

I like KB2VXA's idea.

And I meant "radiation pattern" not propagation characteristics, although they are practically the same.

 

[elephant]

This may seem over simplistic, but I use to live in a single wide mobile home. I placed a magnetic mount
"car" antenna in the center of the roof. I had the best luck getting out with that set up. I could talk 15 miles
barefoot. On the days that skip was rolling, I could talk from Nebraska to Florida without any problem. All this
without any extra power. I figured that the mobile home provided an excellent ground plane.

Just a thought.

 

[jhooten]

One of these:
DBLBRKT Dual 3-Way Mirror Mount or use to make single band base-station dipole. Includes SM1 antenna mounting studs. Dual 3-Way Mirror Mount or use to make single band base-station dipole. Includes SM1 antenna mounting studs. Products Model: DBLBRKT

and two short fiber glass type whips.

Mount vertical on the back side eave and it cannot be seen from the street

 

[tuscaroradave]

Well, after a few days of studying antenna theory and antenna basics I went ahead and made my first 1/2 wave dipole antenna. I picked up a Uniden Washington coupled with an Astatic desktop mic and got an SWR meter and some other odds and ends from Radio Shack. I used 10 AWG wire for the dipole and trimmed it down 1/4" at a time until according to my new SWR meter I achieved an SWR of 1.1 on channel 1 and 1.4 on channel 40. I tuned the antenna in to channel 26 where most of the local base operators hang at. With some cleaning of some pots etc.etc.using some contact cleaner I got the $40 Washington talking rather well. I have the dipole inside the house and it is working perfectly.

I think I'll try my hand at building a full wave dipole for up on the roof of the house. This was a fun project and I'd like to thank all that gave suggestions here.

 

[LtDoc]

There are a lot of "if's" and "but's" with antennas. Very simply, antennas would rather be above stuff than beside stuff, and usually don't 'like' being under stuff. That 'stuff' includes metal and non-metal thingys. Almost anything will affect an antenna to some extent. If that "anything" is a conductor of electricity it will have more affect than non-conductive stuff. So, the 'best' place to put an antenna is away from everything around it and as high as possible. From there, you have to do some compromising to 'fit' your particular situation (all of us do), and that's about as 'normal' as it can get.
Having said that, and since you've already found that the antenna you made 'works', and if you wanna try something else, why not? I think it's fun to experiment with antennas. It is also not really as simple as it may seem, there's still a lot of those "if's-n-but's", and until you encounter a few of them telling you about them isn't really going to make a lot of 'sense' to you. That's where that 'book' stuff about antennas comes in real handy! You won't have to make all those mistakes that others of us have made. (At least, not too often, you know?)
Have fun!
- 'Doc

 

[Baskt_Case]

I like the vertical inside of a PVC flag pole idea.

 

[k3cfc]

First of all i would never consider a 2990 they by nature sport a problem with warbling. am and ssb. what you need is an antenna book and a good antenna analyzer like an m f j antenna analyzer. and remember no question is stupid this is how you learn.

Good Luck

 

[tuscaroradave]

I have moved the dipole up on to the roof now and after a few days of repositioning it to get it a few feet off of the roof and adding a better mic I have it positioned where (despite being on the flat side) I can talk to the local guys with base radios and catch a lot of the skip rolling in too. The SWR is still low and while the modulation is not all that strong the local guys (within 15 miles) are getting 7 pounds or so on me with no apparent bleed over in any of my neighbors TVs. For now I am satisfied with it.

A buddy is wiring up a 5 pin connector to a Turner +3 mic for me that he says should work well. While being a bit of a challenge so far it has been fun to get up and working good and that's the reason I bought all of this stuff, to have some fun without being a thorn to any of my neighbors.

 

[kb2vxa]

"A buddy is wiring up a 5 pin connector to a Turner +3 mic for me that he says should work well."
Work well doing what? You don't need to crank it up to over-modulated cheese grater level and give everybody ear bleed to be heard well and obviously you already are. I'll bet my 2c against a box of cop shop donuts that when you get the gain set for max level without that fuzzy around the edges sound it'll be pretty close to what you have now.

Oh, the average CBer thinks the louder the better and will give you a good report on distortion so bad he can barely understand what you're saying. Best choose critical listeners and go with the law of averages when it comes to air checks, somewhere between turn it up and turn it down is the sweet spot... that is unless you can borrow a rig (no antenna on it) and listen to yourself in headphones. Take it from Ricky Nelson; you can't please everyone so you've got to please yourself. (Garden Party)

"...I bought all of this stuff, to have some fun without being a thorn to any of my neighbors."
That's another thing, over-modulation causes splatter on adjacent channels and can cause RFI so to borrow a phrase from Pink Floyd; careful with that axe Eugene.

 

[tuscaroradave]

First of all i would never consider a 2990 they by nature sport a problem with warbling. am and ssb. what you need is an antenna book and a good antenna analyzer like an m f j antenna analyzer. and remember no question is stupid this is how you learn.

Good Luck

Thanks for the tip on the 2990 and for giving me a little slack as an infant in the radio world. The humility is appreciated.

"A buddy is wiring up a 5 pin connector to a Turner +3 mic for me that he says should work well."

Work well doing what?

Sorry, I forgot to mention that the Astatic Mic that came with the Washington base had a squealing problem when the tone control is moved anywhere above it's lowest setting making it annoying to use so the Turner mic would work well at simply talking. I am working with a guy who is a CBer and a Ham radio operator to get my radio set up as best as possible without splatter or over modulation and so far it is working out well enough as I consider him to be the critical type of adviser that you mention.

When I was a kid I had the Relics album from Pink Floyd and remember the song you mention above.

As always Thanks for the replies and for the advice.