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A Dipole for your CB Base Station?
- Thread starter Robb
- Start date
Very gracious response. Beetle means well. I have a wanna be elmer that lives by me that says if you don't build it you ain't a real ham. Of course he is retired and has all day to build stuff. Me? I don't always have the time to get on the radio let alone build stuff all the time. I did build a multiband ladder line fed doublet that works great so I know the satisfaction of rolling your own. But in our busy lives sometimes it is just more practical and expedient to point, click, pull out the credit card, and there it is at the front door in a box. Yeah buddy.
Don't get me wrong, I am not opposed to working on or building something. I work on radios and related equipment close to 60 hours a week. Sometimes its simpler to buy something already assembled and figured out. I will build my own again. As a friend of mine coined "it's not what you buy.....it's what you build" This was inreference to 4 wheel drive trucks, but the meaning is the same.
Robb,
I bought one of those a ways back for my CB. As you know from last year, and currently, I am still experiencing 3 db of noise level at night on my base. Lately, I have noticed, that by morning, the db level of floor noise is gone. Not even 1 db. Strange eh? Then a thought occurred to me. Maybe it is a bad halide street lamp buzzing as soon as dusk approaches, and at dawn, the noise is gone.
Anyways, in which brings me to something I read last year and correct me if I'm wrong, but by mounting a dip pole antenna horizontally, one can then avoid the vertically polarized interference or noise that our vertically mounted base antennas are picking up. Same as in using a beam antenna horizontally.
So I am also wanting to set mine up as soon as it gets warmer out.
Interesting post Robb.
I bought one of those a ways back for my CB. As you know from last year, and currently, I am still experiencing 3 db of noise level at night on my base. Lately, I have noticed, that by morning, the db level of floor noise is gone. Not even 1 db. Strange eh? Then a thought occurred to me. Maybe it is a bad halide street lamp buzzing as soon as dusk approaches, and at dawn, the noise is gone.
Anyways, in which brings me to something I read last year and correct me if I'm wrong, but by mounting a dip pole antenna horizontally, one can then avoid the vertically polarized interference or noise that our vertically mounted base antennas are picking up. Same as in using a beam antenna horizontally.
So I am also wanting to set mine up as soon as it gets warmer out.
Interesting post Robb.
well mouning it hoizonally normally takes all that out [no gaureentee] heres something 2 think about if ya talk to local using verticle polarized antennas you,ll either lose them or most likely notice a drop on signal both tx/and rx.
HOWEVER if you talk alot of dx having it horizonally it should work better for this '
then what verticle does
Go ahead with your project with the metal pole it should work fine. Using a metal support for an inverted 'V' is very common and should have no significant affect on the antenna's performance.
An inverted 'V' is a horizontally polarized antenna so there will definitely be a difference in what you hear if you've been using a vertical antenna. As already pointed out, local or non-skip stations will be weaker to you and you to them. That's normal. But 'skip' stations could certainly be louder. A signal 'skip' means a change in polarization which can be handy at times, not so handy at others.
- 'Doc
An inverted 'V' is a horizontally polarized antenna so there will definitely be a difference in what you hear if you've been using a vertical antenna. As already pointed out, local or non-skip stations will be weaker to you and you to them. That's normal. But 'skip' stations could certainly be louder. A signal 'skip' means a change in polarization which can be handy at times, not so handy at others.
- 'Doc
For a flat SWR you will have to set the wires at a 120° vee, then tune for flat.
- If you cut or extend the wire to tune for flat at a lesser or greater vee angle you will actually be increasing the rectance and losing performance. Not a big loss but better to cut it to the right length and live with up to a 1.5:1 SWR, depending on the vee angle.
At a 90° vee (37ohms, 1.5:1 SWR) you'll have equal energy in both the vertical & horizontal polarizations in all directions ('spherical pattern'?) unless you're after more broadside horizontal performance.
- If you cut or extend the wire to tune for flat at a lesser or greater vee angle you will actually be increasing the rectance and losing performance. Not a big loss but better to cut it to the right length and live with up to a 1.5:1 SWR, depending on the vee angle.
At a 90° vee (37ohms, 1.5:1 SWR) you'll have equal energy in both the vertical & horizontal polarizations in all directions ('spherical pattern'?) unless you're after more broadside horizontal performance.
For a flat SWR you will have to set the wires at a 120° vee, then tune for flat.
- If you cut or extend the wire to tune for flat at a lesser or greater vee angle you will actually be increasing the rectance and losing performance. Not a big loss but better to cut it to the right length and live with up to a 1.5:1 SWR, depending on the vee angle.
At a 90° vee (37ohms, 1.5:1 SWR) you'll have equal energy in both the vertical & horizontal polarizations in all directions ('spherical pattern'?) unless you're after more broadside horizontal performance.
Not necessarily true. The height of the antenna and distance from metallic objects in the near field are at least as important as the angle. The ground composition and resistance figure prominently in the mix also. Perfectly horizontal dipoles work just as well as the variant known as the "inverted vee". No two antenna installations are going to be exactly the same. You have to put it up and try it out
Of course there are always exceptions to the rule (antenna theory) - that goes without even needing to be said, but that doesn't discount the rule as good starting practice.
You are right in that 'always exceptions to the rule' thingy, but where did that 'rule' come from?
I think the idea that there can be a 'perfectly flat' SWR at more than just one frequency is a misconception that has become one of those 'myths' that seems to be very common now. The fact is that there are no absolutes with antennas.
That 'goes without even needing to be said' only applies when all parties DO know what wasn't said, everyone is on the same 'page'. There's only one way to be sure of that and that's to go ahead and say it. You gotta establish some base lines or things fall apart very quickly.
- 'Doc
I think the idea that there can be a 'perfectly flat' SWR at more than just one frequency is a misconception that has become one of those 'myths' that seems to be very common now. The fact is that there are no absolutes with antennas.
That 'goes without even needing to be said' only applies when all parties DO know what wasn't said, everyone is on the same 'page'. There's only one way to be sure of that and that's to go ahead and say it. You gotta establish some base lines or things fall apart very quickly.
- 'Doc
I have an 'inverted V' dipole in my attic and it works great, very wide band low SWR range. Antennas without loading coils to shorten the length generally have lower swr over a wider range which is why it's such a pain to tune tiny loaded car antennas.
The cost was $0 dollars, best antenna no money can buy.
I used the plastic lid from a mayo jar and attached a coax connector through the center of the lid pulled from a dead radio. Then I stripped old TV coax down to the copper by using a sharp knife. Soldered this to the coax connector. Hung the mayo lid from a rafter then ran the two 100 inch legs down opposite each other and attached to suitcase handles.
The cost was $0 dollars, best antenna no money can buy.
I used the plastic lid from a mayo jar and attached a coax connector through the center of the lid pulled from a dead radio. Then I stripped old TV coax down to the copper by using a sharp knife. Soldered this to the coax connector. Hung the mayo lid from a rafter then ran the two 100 inch legs down opposite each other and attached to suitcase handles.
I've got a two story house with a hip roof. The top is maybe 35' and it's the highest pitch the contractor would do. It's a little greater than 45 degrees. Can I ran a dual inverted 'V' dipole successfully from the peak down?
I had a inverted v one in my old apartment. It worked great with all my cbs use to talk skip all over the place.