A good homebrew 2m/70cm antenna to build for on the roof.

I'm looking for a new challenge. It must be reasonably simple though coz I'm a thicko. I have managed dipoles and T2LTs for 11m before. I wont mention some of the monstrosities I tried to build in my earlier years. Lets just say the front of my house resembled Windy Millers windmill at one point. I think I even attempted to turn my bedroom into one big antenna. Can't remember how I got on with that project though I must admit my sperm count isn't what it should be I guess  
I want to make a simple 2m/70cm antenna that I can put up on my roof. Something that's going to aid me not just for receiving but for transmitting also, for when I pass my foundation(there's positive mental attitude for ya ). I look forward to the flood of suggestions from you guys.

73's

My first 2m/70cm was a home made job.
Found a video on the net and followed that.
2 lengths of welding rod the type used with gas welding.
Literally bent in a tight U with one end at 19" and the other at 9" those are just a guess but you will find the video easy enough you need 2 the same.
I then got some plastic conduit and a junction 3 way and with a washer i bolted the 2 rods into the junction and fitted eyes to a length of coax and fastened them with a second nut to the 2 bolts.
Fitted the conduit over them and a third bit so i could fix it up on the end of my old shack.
I made the rods a tad longer so i could trim for SWR but only had to take off what i added.
Look up some videos i found plenty.
Forgot to say it worked well.

J-poles, J-poles, J-poles.....Slim Jim's.

That's what you'll tend to find or be suggested when asking for a dual VHF/UHF antenna. They'll come in various 'flavours' too like the 'copper cactus' made from copper plumbing pipe, 300 ohm ribbon type feeder or apparent colinear types with bends, windings or bits of coax purporting unsubstantiated 'gain'.

Knock yourself out, have a bit of fun, don't worry about failing or landing up with a poor antenna.

Most then go on to buy a typical 'white stick' solution.....


For 2m operation I built an extended double Zepp antenna (basically a long dipole) from bits of wire and garden canes. It has some gain and performs flawlessly in the loft where it still remains in use today. Peter Parker VK3YE explains one out nicely on a video of his :-

https://youtu.be/Q-t8NBL67fc

It just about manages UHF too and almost as poorly as some of the other dual band affairs!.....Best have another antenna for 70cm.

For UHF I made a smaller scaled down version of the above but a simple short dipole will work better than most other suggestions.

All of these work and are mounted in a loft too....not everyone has success with a typical J-pole and usually attribute strange notions like the roof tiles 'attenuating' the signals for their failings.

You'll also usually hear about how you need 'better coax' for any of these to work but if you keep coax runs short losses are far less. I actually use good quality TV type coax with the 75 ohm impedance not being an issue and the foil screened foam stuff has far less losses than most cheaper coax cable yet cost a fraction of the price. Usually available from most local DIY outlets too instead of your well marked up radio emporium.


If you simply want to hear the nearest repeater then knock yourself out with any old bit of bent wire. If you want to hear simplex operations and far more repeaters further afield then build a 'better' antenna.

Repeaters have made people lazy with VHF/UHF operations and you can do so much more than you'd think possible. 


All the best,
Victor

Good morning Alan 

That sounds much like one I was watching earlier. That was done with coat hangers though and it was rough and ready but did the job. Yours sounds nice and tidy. I think a trip to B&Q is on the cards in the near future. I'd be happy with that sat on my roof. 

Good morning Victor

I was looking at J Poles. Looks like the slide off a trombone   One for the future I think, as is the Double Zepp. The Zepp looks easy enough to do but I think that one would have to go on a pole in the garden rather than on the roof. 
Yes the coax issue was brought up on a few videos I watched. RG213 was mentioned. I could buy another rig for what it would cost me for that stuff to reach the bottom of my garden. Getting RG8x made my wallet gasp for breath but I was never gonna go as low as RG58.  Well I didn't realise you could use TV coax for radio. I always thought 50 ohms was a must. That's something else learned.  

Thanks for the suggestions fellas. I will certainly be giving them a try. I will be sure to post pictures of my efforts in the forum.

Enjoy the rest of your weekend fellas

73's

Paul

Look forward to some pictures of what you're up to Paul.

Yep, 75 ohms will at worst give you a SWR of 1.5:1 as far as impedance but I've used it for all sorts and often have a lower SWR. Nowadays I'm all about open wire feeders and 600 ohm ladder-line.

Enjoy your Sunday......I'm off for a bit of toad-in-the-hole roast soon with just me and the missus then we'll probably nod off on the sofas digesting it!


73's to you buddy,
Victor

Hi All,

And just a quick question on suitable antenna materials if I may?  I have a couple of 3-4 metre lengths of 79 strand copper speaker wire languishing in my hallway currently, as they're bound for the electrical recycling.....I keep on looking at them, as if in some way finding them useful to re-use for an antenna?

Your thoughts are welcome

Cheers,

Simon.

Hi Simon,

Good quality copper cable is perfect for antenna experiments it just depends on if you have enough of the stuff.


For your short lengths you could build a 2m dipole, an EDZ I mentioned above, a two element yagi beam, a Moxon rectangle, etc. etc.

Obviously wire is 'floppy' compared to nice aluminium tubing but it's also better conducting. Strap it to some nice bits of wood, garden canes, dowelling, plastic piping or whatever to hold the shape you're after......it doesn't have to be "pretty" to work.

Little tip - after you've built a working antenna with everything connected and trimmed to size seal the ends of the copper wire with something like the better half's nail enamel nail varnish to prevent the copper corroding. 

If you're going to mount such a monstrosity outside then a bit of external use varnish wouldn't go amiss to waterproof it otherwise stick it in the loft or use it as a temporary setup. 


I still think building and experimenting with antennas is about the most fun you can have with bits of wire.

All the best,
Victor