Antenna Madness

Keep the opinions coming. This is just what this newb needs.

I'm thinking more like Realtor at the moment. I only want 1 multipurpose (compromise) antenna for now. Gotta get the wife and neighbors slowly adapted to these things, and I need to figure out...everything.
 
Balun for coax to long wire?

Question: I'm planning an inverted-L long wire antenna. The wire will start at ground level (first 8' in thin PVC pipe for safety) right next to my ground rod. Do you think I could run about 12' of coax from the tuner to a 4:1 voltage balun at the wire, with one output of the balun connected to the wire and the other to ground?

ETA: I said balun, but I think I mean unun since both ends are unballanced. And after more reading it looks like 9:1 would be better for a long wire. What do you think?
 
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I used this loop to attach a rubber band. The rubber band is connected to a hook I screwed into the inside of the pipe cap. (pic #2) This keeps the wire straight and fully extended inside the pipe. (pic #3)
Cool design. I would have gone with something other than a rubber band, they just never seem to last long without losing all elasticity.
 
Cool design. I would have gone with something other than a rubber band, they just never seem to last long without losing all elasticity.

The rubber band isn't under much stress, I only used it to keep the wire from scrunching up inside the pipe under gravity. The plans didn't call for it, that was one of my own modifications. Also, I didn't use any glue in the assembly, so the internals can be easily removed if I choose to reconfigure it later.
 
I know nothing of the science on this, but I had a stereo in my folks' old ranch house. I took a long hunk of speaker wire, ran it out the window, up to the roof ridge, then had a "T" go out down to the gutter on each side. I then hooked this up to the antenna input on the stereo. That whole Summer, I picked up stations in Western Mass and New York state.
 
Great all around HF antenna is the G5RV. I've had one up and use it on 40 and 75 meters for 25 years. There are mono band antennas that will work better but for all band / all around use they work very well. Angle of take off is great, and that is more important than power. 73, Gary- W1GRC
 
Coupled Resonator Dipole

In a recent QST was an article on coupled dresonator dipoles: basically a dipole with another wire parallel to it cut to resonate for a different band. The author used 450ohm ladder line which isn't ideal since for best performance the spacing between the wires matters. But, it fit my desires of a simple, portable, no-tuner wire antenna that fits in a 1 gallon zip-lock bag. So I made one for 20/40M

I cut the ladder line for 20M then extended the ends of one conductor for 40M. The 20M wire is one piece (not cut in the middle). The 40M wire is cut in the middle and connected to the coax. I have a 1:1 current balun at the feed point for no particular reason.

After trimming it's a good 40M dipole. SWR on 20M isn't great and gets close to 2:1 at the band edges. The 40M wire's performance in 15M leaves a lot to be desired with SWR between 2 and 3, but in a pinch I'm comfortable with that. So long as I keep the transmitter's power below 50% I don't think anything will get hurt. So, I've got a 2 (and a half) band no-tuner antenna with no bulky traps.

My next project is an end fed half-wave. For field use I like that the feed point is at one end so the feed line is short and on the ground. I would love to know what's in the match box on this 40/20/10 antenna.
 
I'm just getting started and only have 2M/440

Car: Hustler 2M/44 mag mount. Works quite nice. I had it on a metal table in my house and could hit repeaters 20 miles away.

House: I now have one of Ed Fong's $22 2M/440 j-poles on my house:

http://cgi.ebay.com/Dual-Band-VHF/U...ItemQQimsxZ20100228?IMSfp=TL100228131002r3069

It is made of twin-lead and comes rolled up in an envelope. All you do is get 5' of PVC pipe, slide it in and mount it to the roof. From Topsfield I can hit Worcester (52miles). He also has a similar one tuned for no PVC pipe for hanging from a tree while camping. On my HT the Gloucester repeater goes from S4 to S9.

Fong is a UC Berkeley PhD and the antenna has been written up several times including in QST. Plans are published, but for $22 + $2 shipping, I don't think I could make 1 that cheap.

Do you guys have lightning mitigation in place for the house antenna?
 
I've moved and that J-pole. It is now in the attic so I don't have a lightning arrestor on it. I do disconnect it during bad weather anyway. My other antennas have well grounded lightning arrestors on them.
 
Do you guys have lightning mitigation in place for the house antenna?

A ground rod array, lightning arrestors on all the coax, and surge suppressors on all the rotor /switch box control lines.
But mostly hoping and praying that the odds work in my favor.
 
A ground rod array, lightning arrestors on all the coax, and surge suppressors on all the rotor /switch box control lines.
But mostly hoping and praying that the odds work in my favor.
Ground rod array? Take this guy with a grain of salt[grin]. What he's not telling you is that he's a "big gun" with a tower, linear amplifier, etc. I have 2 ground rods 10' apart just outside my shack and almost anyone will tell you that's overkill for a simple station.
 
Ground rod array? Take this guy with a grain of salt[grin]. What he's not telling you is that he's a "big gun" with a tower, linear amplifier, etc. I have 2 ground rods 10' apart just outside my shack and almost anyone will tell you that's overkill for a simple station.

More like a bb gun. In fact I'm getting a little annoyed right now I can't reach 7Z1AO in Saudi Arabia on 40meters. I'm going to blame the fact that I've been playing around with my new mic and all the crap i bought with it. I have a problem :)
 
So i got a roll up j-pole from here:

http://www.2wayelectronix.com/

Got the dual band with 16' of length and a SMA connector for my FT-60. I hooked it up last night with the antenna inside, hanging off a blind on the window. I was able to come in loud and clear on the local repeaters like Beverly and gloucester and was able to connect to Chester NH but i don;t think the voice would have been decent. I really want to get this mounted outside.

I was thinking of using PVC for support and with paracord run the roll up up through the PVC mounted to the peak of my house. I don't plan to leave it permanently and will take it down after each use.

Thoughts?
 
So i got a roll up j-pole from here:http://www.2wayelectronix.com/
I was thinking of using PVC for support and with paracord run the roll up up through the PVC mounted to the peak of my house. I don't plan to leave it permanently and will take it down after each use.

I wouldn't put it inside the PVC pipe. The higher dielectric constant of PVC vs air will lower its resonant frequency so your VSWR will go up. There was a guy selling twin-lead J-poles "kits" that came rolled up and you had to put it inside 200psi PVC pipe. It had to be 200psi. The thick sched-40 or the thin 100psi stuff would change its frequency. It drove some of us nuts finding the 200psi stuff. I would hang it up naked.

Still, it will only cost a few bucks for you to try, and maybe the shift won't be enough to matter. Use the thin 100psi stuff if you try it. Keep us posted.
 
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I wouldn't put it inside the PVC pipe. The higher dielectric constant of PVC vs air will lower its resonant frequency so your VSWR will go up. There was a guy selling twin-lead J-poles "kits" that came rolled up and you had to put it inside 200psi PVC pipe. It had to be 200psi. The thick sched-40 or the thin 100psi stuff would change its frequency. It drove some of us nuts finding the 200psi stuff. I would hang it up naked.

Still, it will only cost a few bucks for you to try, and maybe the shift won't be enough to matter. Use the thin 100psi stuff if you try it. Keep us posted.

I have that one...I also picked up the 200 stuff at Lowes. It works pretty damn well...and I have no issue with my SWR.
 
I picked up a Diamond X30 for my base antenna. Figured i would buy a length of plumbers pipe to attach it to. I plan to mount it near the peak of my roof. Anyone got any good ideas how to attach it?
 
What do people do about lightning? Is this something you make, or buy? I have a TV antenna in my attic I want to move outside, but need to figure that out first.
 
You need to give the lightning a path to ground. That path needs to be outside your house. You do NOT want to bring the lightning indoors.

Code requires the antenna mast be grounded. Read here. Typically, close to where the antenna cable enters the house you have an arrestor that connects to the antenna cable and ground. The mast and arrestor are grounded with a heavy wire (#10min) going down to a ground rod or outside water pipe (not your gas pipe!).

Without the arrestor, even if you don't take a direct hit, the antenna will pick up the EMP from a nearby strike and fry the TV. In fact, even with an arrestor, if the antenna takes a direct hit your TV is probably toast, but the damage will be much less than if the 1.21gigaWatts in the bolt decides the easiest way to ground is through your livingroom.
 
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Rat Tail on HT Antenna


Put a rat tail on your HT!


I bought one of those super-cheap Nagoya 2M/70cm antennas ($12 on eBay). It's 15.5" long so I figured it would outperform my 7" Yaesu duck on my FT-60. It perfomed identically. Someone suggested I try a rat tail, so to tonight during a somewhat distant 2M net I compared the Yaesu duck, the Nagoya and my Ed Fong shirt-pocked J-pole, with and without the end of an 19.5" piece of insulated 22AWG wire wrapped around the base of the antenna. Wow! Rat tails really, REALLY make a difference.

ANTENNA___NO RAT__WITH RAT
Yaesu_______S5_____S8 to S9+20
Nagoya______S5_____S8 to S9+20
J-pole_______S8

With the rat there was a bit more sensitivity to where I stood (S-meter moving up and down as I walked around), but wholy-cow, what a difference. All I can say is that I'm a rat tail convert. That magic little piece of wire is now in my HT travel bag.


Here's my Baofeng and Yaesu HTs with the rats installed. I attach the wire to one of the belt clip screws.
DSC01367_zpsd4e7a2d9.jpg
 
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I was looking at this article about a roll-your-own ground plane antenna that was in the giveaway I got from the ARRL. Looks pretty simple to make; however I have one very basic question.

How do I orient it? Parallel to the ground? Vertical? I was thinking of putting it in my car (as opposed to buying a magnet mount antenna) but I'm not sure if hanging it in, say, the back window would be a smart move. From what I've read today, it looks like it needs to be parallel to the ground - so would putting it on the privacy cover over the back of my little SUV work?
 
I was looking at this article about a roll-your-own ground plane antenna that was in the giveaway I got from the ARRL. Looks pretty simple to make; however I have one very basic question.

How do I orient it? Parallel to the ground? Vertical? I was thinking of putting it in my car (as opposed to buying a magnet mount antenna) but I'm not sure if hanging it in, say, the back window would be a smart move. From what I've read today, it looks like it needs to be parallel to the ground - so would putting it on the privacy cover over the back of my little SUV work?

The weather is nice now. Just bolt it to the top of your helmet for when you go for a ride on your bike. [wink] [laugh]
 
...and I was only trying to make a funny.

Found these though....

a15800-61-yagi%20antenna%20helmet.jpg


060_068.JPG=450


helmet%20cam.jpg


ari-helmet.jpg


helmet_antenna_mount2.jpg


Ya, I know, I'm of no help.
If I had to guess though I'd say you'd be best off if you could mount it to your roof/roof racks. [wink]
 
helmet_antenna_mount2.jpg


Ya, I know, I'm of no help. [you can say that again! - R.]
If I had to guess though I'd say you'd be best off if you could mount it to your roof/roof racks. [wink]

None whatsoever. I don't have a roof rack. I do like the ingenuity in the above picture, though... even if I wouldn't ever be caught wearing one of those dorky little helmets.
 
I was looking at this article about a roll-your-own ground plane antenna that was in the giveaway I got from the ARRL. Looks pretty simple to make; however I have one very basic question.

How do I orient it? Parallel to the ground? Vertical? I was thinking of putting it in my car (as opposed to buying a magnet mount antenna) but I'm not sure if hanging it in, say, the back window would be a smart move. From what I've read today, it looks like it needs to be parallel to the ground - so would putting it on the privacy cover over the back of my little SUV work?

For 2m FM work, the part that is attached to the center of the coax goes vertical. The "ground plane" wires..generally horizontal.

The reason for a ground plane is to emulate the bottom half of a dipole antenna (which is what that rat tail in post #81 does).

Propping it on the privacy cover in the back of the car will do a pretty good job channeling the RF energy right at the back of you head. I don't recommend it, especially if you put more than a few watts into it.

The sheet of steel that generally makes up the roof of the car makes a kickin' ground plane, and a luggage rack, a really nice mounting structure. (FYI: A 1/4 wave whip for the 2m band is only 20.5" long)
(eta: bummer on no luggage rack....magnet mount?)

Also, look up the J-pole antenna. I actually built one out of a 108" CB whip that worked pretty doggone well, and doesn't need a ground plane.
 
For 2m FM work, the part that is attached to the center of the coax goes vertical. The "ground plane" wires..generally horizontal.

The reason for a ground plane is to emulate the bottom half of a dipole antenna (which is what that rat tail in post #81 does).

Propping it on the privacy cover in the back of the car will do a pretty good job channeling the RF energy right at the back of you head. I don't recommend it, especially if you put more than a few watts into it.

The sheet of steel that generally makes up the roof of the car makes a kickin' ground plane, and a luggage rack, a really nice mounting structure. (FYI: A 1/4 wave whip for the 2m band is only 20.5" long)
(eta: bummer on no luggage rack....magnet mount?)

Also, look up the J-pole antenna. I actually built one out of a 108" CB whip that worked pretty doggone well, and doesn't need a ground plane.
I was actually thinking of laying it flat on the privacy cover - the antenna, as built in the article, has only three elements, all in the same plane.
 
I'm just getting started and only have 2M/440

Car: Hustler 2M/44 mag mount. Works quite nice. I had it on a metal table in my house and could hit repeaters 20 miles away.

House: I now have one of Ed Fong's $22 2M/440 j-poles on my house:

http://cgi.ebay.com/Dual-Band-VHF/U...ItemQQimsxZ20100228?IMSfp=TL100228131002r3069

It is made of twin-lead and comes rolled up in an envelope. All you do is get 5' of PVC pipe, slide it in and mount it to the roof. From Topsfield I can hit Worcester (52miles). He also has a similar one tuned for no PVC pipe for hanging from a tree while camping. On my HT the Gloucester repeater goes from S4 to S9.

Fong is a UC Berkeley PhD and the antenna has been written up several times including in QST. Plans are published, but for $22 + $2 shipping, I don't think I could make 1 that cheap.

found this:
Dual Band VHF UHF Ham Murs GMRS Commericial Portable Emergency Antenna | eBay
i am assuming it's the same antenna you're talking about. wondering what frequency range you bought? the uv-5r i have covers a wider range of frequencies than the antenna does (at least in the description). wondering if i try to tune in 138.000 or 475.000 if it will work. thanks.
 
I bought the dual-band one for the ham bands. If you are just receiving you'll be able to hear a lot outside the advertised bandwidths. But for transmitting the SWR will go way above 2:1 real quick and piss off your transmitter circuitry, so only Tx in the usual ham band.
 
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