Cheap Home Brew CB / 11m antennas for Attics and Lofts (also for 12m and 10m too)
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- Опубликовано: 5 июл 2024
- Loft / Attic Home-Brew CB antennas. Three Rules: Needs to be compact, easy on the wallet (cheap!) and easy to construct and understand. I have built loft / attic antennas, both verticals and dipoles for 11m (10m actually) with varing success. Other ideas are Delta Loops, horizontal loops and also remember commercial mobile antennas can ideal for lofts and attics - you will need a bit of a ground plane though. Chicken wire or just regular wire can assist. Beware that loft antennas can sometimes sound noisy because they will be directly above all the electrics in the house. However, they are still cheap and fun to make. Good luck, Callum.
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Thanks for taking the time for us cb guys Calum. Lot of hams get thier feet wet with CB and GMR before making the plunge into ham. Many hams still like thiers c.b., Dx Commander Rocks all the Radios !
Back in my CB days (early 80's) I lived in a top floor apartment with a closet which I discovered had a hatch that opened into the attic. One night I crept up there and strung an 11m dipole (each end of which extended over my adjoining neighbor's units). It worked GREAT. It might still be up there, since I didn't remove it when I moved out!
Haha! I did similar.. A 2 x 3/4 wave dipole (probably resonant on around 9MHz on the fundamental!) across the top of the appartment.. Awesome.
Hi Cal, tnx for the video. My first base CB antenna was a DV27 mobile antenna mounted on a biscuit tin lid and some tin foil radials. That was back in 1980 on AM. I was only a schoolkid and too young to get a ham licence then. Worked fine for local contacts.73
Very cool!
Thanks for taking the time to teach us how to fish.
It's better to know how it works.
I hope to build a 11 meter antenna and some antennas for a few different bands.
I made an inverted V for 11m and it worked great
Cal, I'm looking at getting into radio again after several years off-air due to health issues and being in electronics at the time. Radio felt like I was taking work home and of course nobody wants to do that, so I sold everything off. It may not have been the wisest decision but it does allow for a fresh start without the mistakes from before. Your channel is helping me remember the things that I've forgot in the time I've been out of it and making it fun again. Thanks a lot.
Ah- great! Enjoy your time playing.. Nothing like a reasonable hobby to have a play with!
Great video. In the late 70's on illegal AM CB I talked to a guy in New York from south Wales, I had a DV27 mobile antenna on a camera tripod in the bedroom but it was an amazing sunspot cycle around then.
Lovely.
The (other) best thing about folding the dipole to a square shape is that You make it omnidirectional.
Do you lose any distance advantage by gaining the omni advantage?
Brings back memories of my biscuit tin lid hidden under my bedroom carpet with the 4 radials soldered on
Sticking my mag mount & Tiger Stick onto that compared to using the oil filled radiator got my 4W out much further & my parents were none the wiser. :-)
Brilliant!!
Excellent advice as always Callum...
Much appreciated!
Man, from mid 80's to early 90's all I had was a DV-27 antenna on a quality street lid handing on a nail outside my window. Worked well.
I ran a 1/4 wave hy gain in the attic of a ladys home once. Seemed to work ok.
Brilliant Cal. Forwarded to a friend to maybe try
100% perfect as always , thank you for sharing .
Thanks again!
I have made a V dipole in my loft works greats later i make a reflector behind it 2 s point more in one directie
Lovely!
Great video, thanks
Great video
DV27 on a biscuit tin, I remember that from the 1980s.
Haha yes!
Another good video; great education for newbies and good revision for old lags. Might be worth mentioning that if you have loft insulation with silver foil like "Kingsapan" or "Celotex" you could have a problem with signal blocking. You could be "bew-gaired" as we say in France! 🤣
Oh goodness me, I forgot about that! LOL
Or you could use it as a ground plane?
@@johniedesk1 That would be great if it's just across the floor of the loft. 👍 But often it's on the sloping surfaces making a Faraday cage. I've never tried it so don't know how bad it would be. Would be interesting to find out. Best 73, G0ACE
@@DXCommanderHQ Sorry to be that annoying smart ass! I only remembered because I keep tripping over some Kingspan panels ! LOL Conversely, my studio is under nearly 800 sq ft of steel roof and I still hit repeaters 50 miles away on 25W.
Great video Callum I love making antennas piece of coax and wire and then play time. Yesterday on fm ch19 Darwin Australia was coming into UK brilliant fun but UK callers was stacked up so could not get back. I have made so really basic antennas people look at them but once they see it preform the face changes.
Happy radio days 73 Cal
Totally agree.. Nothing like mucking about and getting an antenna working for free..!
Just did an attic antenna video myself. A high gain 5/8 wave ground plane, pretty damn good receive for what it is. 73👋🏻
Could you build one and sell it maybe? :)
Use a half wave section of 50ohm coax to make a 4:1 balun. It's a great little trick that all hams should learn. Easy to make, minimal losses, and does a great job at feeding a balanced antenna with an unbalanced line.
Awesome vid😎⭐⭐⭐⭐⭐
Thanks for the visit
throw a mobile cb antenna in the attic with a wire groundplane and your off
Jolly good show jolly good
Jolly fine!
Made me feel good talking about not to worry about SWR at 1.5 im constantly on a mission to get the best swr on my half wave end fed and adjusting it for the past 3 weeks lol its driven me mental lol maybe do a video on the whole subject and do test results with contacts? thanks
Steven, I think a full demo might be a cood idea! Just to prove the point.. Nice.
I have 60 dx countries on 15m at 1.5-1.7 swr. on 40m 34ft ground mounted vertical. Russia to Australia from AZ.
Thank you
Welcome!
My first HF antenna was an inverted V 10M I built and installed in my attic. I was talking to a local friend on 10M and a guy from San Diego CA broke in and we chatted about 5 min before the band disappeared him. My very first HF contact and it was about 1570 miles. I cut the wires according to the formula because at the time I didn't have an swr meter but I did have a tuner. Back in the old days I talked skip at various distances on CB so antennas for 10, 11 or 12 should work pretty much the same when cut for a particular band. I haven't had a CB radio for years but am considering one to play around with. It never hurts to have an extra means of comms. Jack K5FIT
Nice memory Jack!
Hey Callum, love your videos, sometime when you get a chance do a video on scaling from one frq. To another, Thanks again. John
Scaling one freq to another.. Yes, I'll add it to the list.
I just wonder how much profit Rover or Family Circle made in the early eighties as everyone i knew had one with a dv27 in Dumbarton lol. :-)
Yes!
Great video - really informative. I have a couple of loft antennas for 11m. One a mobile mounted to a heavy galv. water tank the other an inverted v dipole. I have tried dx'ing in supposedly favourable propagation conditions and have yet to make a contact. I am just running a standard 4w FM rig on the mids and UK40. I also have a question regarding rf losses due to being in a roof space. My roof is typical cement tiles. I have no issues receiving signals just concerned maybe my 4w ain't getting out as well due to the roof structure? Any thoughts appreciated.
OK, so although there will be SOME attenuation, you SHOULD be OK.. Now in the UK, we're allowed 12W SSB now - so when you have cut your teeth on FM/AM, maybe have a look at that. SUnday nights is apparently the time for nets and stuff.. Down towards 27 335 or something rings a bell. Not sure if that's FM or SSB though. G'luck!
Thanks this helps me a lot - HOA challenges ....
You got this!
nice video, confirmed a few theories i had worked out myself as i seem to be making skip contacts abroad who was using similar antenna to myself! so i guess that confirms my thoughts! maybe if i want to get different contacts i should try different antennas to match the new contacts! yago, dipole etc! :)
Good stuff!
I have used attic antennas for standard power CB radio and for QRP ham radio, but when I tried a 100 watt radio, I saw arcing between the antenna and the wooden rafters of the attic. That was the end of 100 watts in the attic for me. Even 50 watts might be risky. One design that can work, is a wire bent dipole, with the inner two thirds of the dipole hung fairly straight (or somewhat in line with each other) and the one third ends of them bent one way or the other to fit. The one third ends don't have to be parallel. Start a bit long, such as 9 feet for each half for CB radio. I use twists of wire to locate the insulators on the element wires, for support.
Arcing on 100W..? You hysically say this? I would love to replicate the experiment. Never seen it.. Ever.
@@DXCommanderHQ This was right at the end of a half wave dipole, so the high voltage tip of a quarter wave element. There are nails and such in the wood, but at that point I didn't see any metal in wood. It was just arcing to the wood from looks of it. It was a 100 watt radio that had been turned up, so it was likely a bit more than 100 watts and some of the older radios could be turned up quite a bit. Maybe not much current or heat, but certainly enough voltage to arc over. I didn't think 100 watts would arc either, so I put the end of the dipole right next to the wood and it did arc. Maybe the humidity and wood were just right for arcing, but it didn't have far to arc and it did. With the older Kenwood's, with 2SC2879 finals, I could get more than 200 watts output, just by adjusting the limiter.
This might just work for my retirement flat.. The attic is right above and it's 6 meter long.. Many thanks, Andy - G7MJV
Good luck!
18 foot radials seem to be the average length. Im gonna try a 3 element 11 meter on flat side, i have a Starduster at moment. Back in the day my Father ran a moonraker 6 connected to his Browning Mark 3 & 4, and akso had a Super Penetraitor other end of home, spent most time on beam playing with his slider. Opening garage doors with the kicker box
What happens if instead of bringing the radials down at a 45 degree angle, one brings them straight down? Also, if you can end load the vertical and make it shorter by folding it over, can one do the same thing with the radials to save space?
A single radial going down would work.
Great video, Callum, and a nice Les Paul on the wall there! As a musician, maybe you'd have a perspective on this question--- I have a standard tri-pod PA speaker stand in my storage unit, and I keep looking at it and wondering, "Hmmm... I wonder what would happen if I placed that stand in front of my ground-level apartment window and mounted a mag-mount mobile-style antenna on top of it?" Would the three legs of the stand serve as a ground plane, or am I just showing my relative ignorance on the subject?
Do it!
Cal, is there any available research on the effect of the wire spacing on linear loading?
Also, for the attic, an alternative to linear loading would be a capacitance hat, just two wires running along the peak (assuming a peaked roof) each way from the top of the vertical element. You may as well use that peak. BUT, do let the ends droop to keep the highest voltage points away from the wood (or anything else flammable).
Bill, good idea with the cap-hat.. Linear loading. I don't know of any formula.. Wider spacing = more loading, that'll all I know.. I am also realising that there is more loss for a FULLY linear loaded element than I appreciated. Working on that.
@@DXCommanderHQ I was thinking of using adjustable spacing for fine tuning without the annoying, harder to undo, step of cutting the wire.
I guess that I'm not too surprised by the loss. I think of top hats (or other capacitance hats), in preference to, say, base loading coils (or tuners) as increasing the portion of the wire that has higher RF current. What current there is in the coming back down wire, being out of phase, spoils the effect. I guess that not just the loading, but the efficiency too, would increase with spacing. Sort of moving in the direction of a bobtail curtain.
If you're in a modeling mood, I'd be interested to hear what would be the impact of taking the end (bottom) of the linear loading wire and running it back up again. Sort of linear loading the linear loading, and avoiding having any confounding loading wire adjacent to the highest current (lowest) part of the (shortened 1/4 wave) vertical primary wire.
feedline impedance transforming So my most recent experiments are showing me more loss than I thought on a fully linear loaded element.. Triple loading works (to an extent) but I think then we are probably after the wrong method..
Hi callum, looking at getting back into radios and using a loft antenna. Being an electrical engineer I've got lots of 4mm cable which is 4.6 Ohms/m. Making an 11m delta loop this would give me 50.6 Ohms therefore which balun would work the best. Would it be 1:1 as i would be wanting to try other frequencies not just 11m.
Great video's by the way.
Thanks in advance 👍
For a loop, you will see between 100 and 200 ohms. So probably a cheap 4:1 would be ideal.
Hey Callum! I couldn't help to notice at 2:55 The calculation is the same as just moving the decimal point one place to the left on the target frequency. Is that the same for any frequency?
No.
Erm.. OK, so take 300 and divide by frequency.. The lower in freq, the higher the wavelength.. Good question.
👍👍
hi
I need a video if possible, as I own a DX Commander Classic and plan to install it on the roof of the house, as the back area of the house is surrounded by buildings. Is this possible and is there an effect on the gain of the antenna or the transmitter, as I searched a lot for a video explaining the installation of the antenna on the roof to no avail.
OK, check the "Gallery" page on DXCommander.com - there are people who have done this and it works.
Could also put a 1/4 wire vertical up into the space with a coil rather than folding it back on itself, working out how high the loft is , how long the wire Needs to be and how many micro hernys ,turns on a 2inch pipe you would need to make the wire fit , while adding radials on the base
Oh yes!
Greetings Commander, will you please suggest a book or books that contain the essential knowledge regarding the installation, operation and repair of amateur radio of the most common types. Thank you in advance for your help.
I don't know of a book like that, I'm sorry.
for a 1/4 wave peace of wire up to 12 awg at hf is 234/f= length in feet! 468/f = length in feet for 1/2 wave! if you use large conductor you will find you have to shorten the length. wire insulation has a effect of lengthening the wire so less is needed. a halo antenna is a good compact antenna.
Yes.. It sort-of lengthens the wavelength, I think you meant to say. It's about 95%.
@@DXCommanderHQ yes that is what i meant to say. and yes to 95% but go bigger than 12 awg in wire gauge you need less length insulation has the same effect.
What would your advice be on my situation I got a antenna tower but far from being able to install it so in the mean time my shop has a metal roof and a lot of large trees everywhere I have a imax 2000 antenna and i got the ground plane kit also I want to hook up for my cb base station intell I can get the tower cleaned up and installed should I just try to mount it to the side of my shop as high as I can get it I have a old mast that I can use to get it higher but probably not above trees and it may sway into some limbs don't have anyone around my area I can ask advice from
It'll be fine from about 20 feet and upwards.. Ignore the trees.
when making a quarter wave wire antenna for 11 meters, how many ground plane / counterpoise radials work best- 3? 4? I could always experiment, I'm just curious what happens when you add more or take them away.
If it's up high - so in other words on a pole and it's a genuine q/wave then 2 will actually work fine. Ideally, sloping down at around 45 degrees (but that is only for the match, not the pattern). On the ground then 16 small 6ft / 2m long ones work just fine.
thanks, great info @@DXCommanderHQ
How do you bend the antenna without it breaking??
It's just made of wire..
What if I have a brand new steel roof? Can I use the metal roof for the antenna?
You COULD use anything that conducts.. But you would need a tuner / SG230 type thing and a ground. You can use the roof as a ground for a vertical though..
@@DXCommanderHQ I think using the metal roof as a ground plane makes more sense. So I could ground the roofing metal to earth and then position the vertical antenna right in the center of the ridge line? As if I were positioning a mobile magnetic antenna mount directly in the center of a car roof? My house is up on a high ridge with a commanding view all around. I would like to be able to leverage the metal roof to my advantage instead of having it be some kind of obstacle that I have to work around.
Oh Callum you made me chuckle with the we as hams don't give a sh*t about it. 😁
Great video mate.
How you getting g on with the 20/40 loaded vertical? Did you have a look at my entry again?
Motters M7TRS 73 👍🏻
No mate.. Been working - doing "REAL" work this week..!
@@DXCommanderHQ yeah I know that feeling. I hardly get time at home to get on the radio. Might try and get a vertical up in the garden soon
73
Good video...1.5 SWR is fine by me, people get to picky with that crap and they are the one's you never hear on the air...ha ha..Are you still going to raffle off your old notebook? I remember you mentioned it last year and i noticed you have been using a new one the past couple of videos...See some of us pay attention...lol
Actualy yes.. I have two filled up now. That would be an interesting fund-raiser for a charity!
@@DXCommanderHQ yes!
Sadly there is one technical issue you have overlooked Cal. My wife ! (she refuses any thought of my having my radio stuff in the house).
How selfish of your wife.
Sorry for your situation. But you must maintain that "Domestic tranquility factor!"😂.
@@johnmayer158 the tranquility factory that the poor guy cannot enjoy his hobby 🙄
I'm terribly sorry to say this, but if you have a partner that won't allow you to do the tings that you enjoy, then you have the wrong partner. It will only get worse. I speak from sad experience.
Oh John!
I use a attic antenna end fed with a automatic tuner from yaesu FC40 vorks gret simple and hidden
Auto ATUs.. Yes, lots of fun.
@@DXCommanderHQ thanks 4 replay.have you ever trayd a dipol antena ended wit resistor made from stainles stiel wier and having center transformer 9:1?
I have approx. 2 in swr of 15 meter 21,140 and it doesn't matter, I tune it with the radio so that it is happy, but I have a friend who operates on 27mhz and swr is very Dangerous and the length of the cable is important, I have tried to tell him not to bother but it's no use.
Ah well, maybe he can watch this video :)
A low SWR does not necessarily mean an antenna is resonant. This should be taught to hams almost right away.
It is.
@@DXCommanderHQ well they're not taking it onboard. The only time a CB antenna will be resonant in relation to SWR is when it is specifically designed to be so. That is, has a 50 ohm feed impedance based around a truly resonant radiator/driven element. The definition of a resonant antenna is even taught wrong to hams. Apparently it's when the radiating element/s exhibits no reactance.
Check the course material..
can I ask a question please re wire dipole type in the loft.
commercial G5RV / half size, cut down to the specs you have shown,
using the supplied ladder line & balun, would this work ?
I used a G5RV half size, in my last location, externally I was lead to believe the feeder (ladder line) had to be 25ft from the ground vertically. ?
that's how I used it & got great results on 11 meters albeit with an external ATU.
so my theory is to use said G5RV cut to req length also the ladder line (may be as the legs & feed are supposed to "match")
would this work as the feed would not be vertical ?
now I am confusing my self 😄
I like to 'play' with antenna building this is a project I'd like to try.
many thanks
73
Cheers & Beers
OK, so the ladder line on a G5RV is the matching section.. So we COULD cut everything proprtionally and it would still work (probably shorten [divide] everything by 3.8) but then it's a bit of a waste because a regular dipole cut for 27MHz in the loft would work the same UNLESS you needed muti-band. PS - You can Z-Shape the G5RV and ust lay the ladder line across the loft - works same.
@DXCommander Brilliant thank you Cal 👍
For dx 27555 💪🏻☺️
OOOOLA OOOOLA lol
@@colourist. not ola ola i am 1at227 and i wrk 286 country in 11 there same ola ola same in hf look when are active bouvet and other activation ☺️🤣👌🏻
@@genoa1979 no offence meant :) just 555 can be very 'noisy' sometimes!
@@colourist. to day good propagation Indonesia usa central america Australia
27.3850 LSB states hitting the UK almost daily
1.5 swr is fine when you have high power. When you have 4 watts 1.5 swr kills all your chances to DX. Do the test yourself
I have. Maybe 1dB. It's in your mind. Laws of physics. BUT I tell you what.. I'dd DO THAT TEST and we can detail it! PS - Power has nothing to do with loss, it's proportional.
Not how it works ,check out the doublet antenna, it can have 10.1 swr with practically no loss
Instead of going thru all these calculations on the fly why don't you just have it all figured out and designed for the "best" possible configuration for channels 1 thru 40 ? ? ? People's time are more important than watching someone else doing math !
Some folks want to know how stuff works. You might be in the wrong hobby if that's not your thing.