End Fed Half Wave.

[TNFrank]

I'm thinking about giving one of these a try. I can get the Balun for one for under $30, get a 16'-20' painters poll and rig a set up to mount it in the yard away from the house and I already have a lot of 14 gauge wire I can use.  So would this be a useful antenna to try or should I just stick with my Inverted V?

[WRYZ926]

I would stick with the 10m inverted v for now.  It is a simple design and works well for you since you only have 10m band privileges.

I know you have HOA restrictions to deal with, but if you can get the center at least 16 feet above the ground it will work much better for long distance contacts.

To answer your question, yes EFHW antennas work well. But you definitely need a NanoVNA or antenna analyzer to make one. They are good for multi band use. Keep this in mind for when you upgrade to general. And you are going to want a 49:1 UNUN for a EFHW.

Another thing to remember about an EFHW, they do need a counterpoise to work well. You can either use the coax as the counterpoise with a good common mode choke closer to the radio or use a separate counterpoise wire with a common mode choke at the antenna feed point. A separate counterpoise wire is more efficient than using the coax as the counterpoise. The counterpoise wire does not need to be very long. You want it to be 0.05 of a wave length. So for a 10m EFHS the counterpoise will be .5 meters or 1.6 feet in length, for a 20m EFHS it will be 1 meter or 3.3 feet. You can go longer but you want to make sure that the counterpoise is not at a resonant length

I occasionally use EFHW antennas for portable setups since they do work on multiple bands. I always use a separate counterpoise wire and a command mode choke at the 49:1 UNUN.

 

[TNFrank]

I guess I'll try to get the Inverted V that I have higher off the ground then to see it that'll help with propagation. I know it's SWR is good so I'll look into a 16' tripod to mount it on. Thanks. 

[WRYZ926]

You're welcome.

[TNFrank]

Amazon had a 64:1 Balun for a End Fed on sale for $20 bucks so I figure what the heck, I give it a try.

[WRYS709]

10 hours ago, TNFrank said:

Amazon had a 64:1 Balun for a End Fed on sale for $20 bucks so I figure what the heck, I give it a try.

I know I can use the Google Machine, but you understand antennas better than I do.  What is a balun and what does those ratios mean?

[SteveShannon]

7 minutes ago, WRYS709 said:

I know I can use the Google Machine, but you understand antennas better than I do.  What is a balun and what does those ratios mean?

Baluns and ununs are types of transformers that transform the impedance from one side of the transformer to the impedance on the other side of the transformer. 
It’s an UnUn if it goes from an unbalanced feedline to an unbalanced antenna, such as coax to an end fed half wave. 
It’s a BalUn if it connects a balanced feedline to an unbalanced antenna or if it connects an unbalanced feedline to a balanced antenna. 
I keep expecting to hear people ask about BalBal, but I haven’t heard of one. I guess that’s just a transformer. 
Coax is unbalanced. Ladder line is balanced. 
End fed antennas are unbalanced. A classic dipole is balanced. 
And the ratio refers to the incoming and outgoing impedance. End fed half waves are generally 50 ohms on the radio side and the wire radiator is typically 2900 ohms, so a 1:49 ratio. Some people use 1:64 ratio transformers. The ratio is so large that the net effect on tuning isn’t significant. 

[WRYS709]

And why is 49:1 better than, say 10:1; and how are these ratios changed for the better?

I ordered an MFJ 1880 80 meter telescoping whip for QRP from HRO and its on its way.  Would a balun help?

The idea of sitting in my backyard, hand-held portable on 80 meters at night fascinates me!

[SteveShannon]

1 hour ago, WRYS709 said:

And why is 49:1 better than, say 10:1; and how are these ratios changed for the better?

I ordered an MFJ 1880 80 meter telescoping whip for QRP from HRO and its on its way.  Would a balun help?

The idea of sitting in my backyard, hand-held portable on 80 meters at night fascinates me!

The RF reflects from impedance differences. A tuned end fed wire is fed where voltage is highest and current is lowest, which means impedance is high at that point. Generally 2450 ohms. 1:49 means that it’s 50 ohms on the radio side of the transformer so RF flows efficiently (low SWR). If it was only 1:10 you’d be feeding a 245 ohm antenna from 50 ohms and you’d have a very high SWR. 

[WRYZ926]

We could go into a very deep dive discussing the different ratios of Balun and Ununs. 

Generally an EFHW is stated as having an impedance of 2450 Ohms. That is why the most common Unun used is a ratio of 49:1 TO figure antenna impedance, take 50 ohms x the ratio of the unun. In this case the antenna impedance is 2450 ohms. Now some find that a 56:1 or 64:1 unun works better for their EFHW. 

A random wire antenna (nothing random about the length) uses a 9:1 unun. You are matching 50 ohm coax to antenna impedance of 450 ohms.

A delta loop and off center fed dipole general y has an impedance of 200 ohms, so a 4:1 unun is used. again, 50 ohms x 4.

As @SteveShannon mentioned, a Balun is used when matching a balanced antenna to unbalanced coax. The most common used is a 1:1 balun for half wave dipole antennas.

There are different types of baluns and some will also act as a common mode choke.

For a further deep dive, one can actually change the resonant point on the lowest frequency and impedance of an EFHW by changing the number of wire wraps around the toroid. This definitely takes a good antenna analyzer to do.

 

For simplicity sake:

Use either a 49:1 or 64:1 unun for EFHW antennas - 49:1 is the most commonly used.

Use a 9:1 unun for a random wire antenna.

Use a 4:1 unun for a delta loop or off center fed dipole.

Use a 1:1 balun for a 1/2 wave dipole.

It is highly suggested to also use a common mode choke to keep RF out of your coax and radio when using any type of unun.

Is everyone confused yet????

[TNFrank]

I've been watching a log of YouTube videos on EFHW antennas. Since I'm going to cut it for 10M it shouldn't be too hard to get the SWR close. I did see that some folks run the wire into then wrap it around a piece of PVC pipe to make a short coil on the wire. That's supposed to help cut RF interference but I don't know how far from which end and how many turns to make it. I need to study more about it. 

Experimenting is half of the fun, figuring out what works and what doesn't.  I'm sure I'll figure it out, then I'll have 2 antennas to choose from.

[SteveShannon]

2 hours ago, TNFrank said:

Experimenting is half of the fun, figuring out what works and what doesn't. 

An analyzer, or even a NanoVNA, makes it more fun! I’m sure you’re tired of me saying that, but it’s really true. 
I’ll stop. I’m delighted you’re doing so well!!

[WRYS709]

I'm sticking to the ones I know best: Verticals! 

[TNFrank]

51 minutes ago, SteveShannon said:

An analyzer, or even a NanoVNA, makes it more fun! I’m sure you’re tired of me saying that, but it’s really true. 
I’ll stop. I’m delighted you’re doing so well!!

I had a NanoVNA, found it to busy even with all the YouTube videos I watched.

[SteveShannon]

14 minutes ago, TNFrank said:

I had a NanoVNA, found it to busy even with all the YouTube videos I watched.

NanoVNA Saver is the best way to make it less busy. I dislike the on-screen interface of the uVNA, but it’s a breeze with NanoVNA Saver.

Otherwise, get an analyzer. They’re simpler and easier to use. I recommend Rig Expert. 

[WRYZ926]

12 hours ago, TNFrank said:

I've been watching a log of YouTube videos on EFHW antennas. Since I'm going to cut it for 10M it shouldn't be too hard to get the SWR close. I did see that some folks run the wire into then wrap it around a piece of PVC pipe to make a short coil on the wire. That's supposed to help cut RF interference but I don't know how far from which end and how many turns to make it. I need to study more about it. 

What coils do when part of the antenna wire is allow for a shorter antenna. The downside is that the antenna will be more narrow banded and less efficient. I personally would not bother with a coil on a 10m EFHW. A coil does nothing to reduce RF interference.

For RFI issues, you want to make an ugly balun by wrapping the coax around a piece of PVC pipe. There is a definite formula that you must follow for the size of pipe and number of wraps the coax makes around it. Another method is to put several wraps of coax through a large toroid. A third method is to install 5-7 clamp on ferrite beads on the coax. These are known as common mode chokes.

If you plan on using the coax as the counterpoise then you want to place the common mode choke 0.5 meters/ 1.64 feet from the unun feed point. Or you can use a separate counterpoise wire attached to the ground terminal on the unun, the length will be 0.5 meters/ 1.64 feet. Place the common mode choke at the unun feed point when using a separate counterpoise wire.

The measurements I gave are for a 10m EFHW only. The formula for figuring the length of a counterpoise is the full wave length of the lowest frequency that the EFHW is tuned for multiplied by 0.05. For a 10m EFHW that comes out to 0.5 meters.

I'm sure you all are getting tired of us saying that you need a NanoVNA or an antenna analyzer to properly tune an HF antenna. But having one or the other will simply tuning antennas and give you way less grief compared to trying to use a SWR/power meter. The NanaVNA and analyzer will tell you right away if the antenna is long or short, making tuning easier.

 

[Lscott]

12 hours ago, TNFrank said:

Experimenting is half of the fun, figuring out what works and what doesn't.  I'm sure I'll figure it out,

You want even more fun then try your hand at antenna modeling.

https://www.eznec.com/

[hxpx]

47 minutes ago, WRYZ926 said:

For RFI issues, you want to make an ugly balun by wrapping the coax around a piece of PVC pipe. There is a definite formula that you must follow for the size of pipe and number of wraps the coax makes around it. Another method is to put several wraps of coax through a large toroid. A third method is to install 5-7 clamp on ferrite beads on the coax. These are known as common mode chokes.

Some more info on building common mode chokes: https://www.karinya.net/g3txq/chokes/

I picked up an FT-240-31 and 5' of RG-58 - it wasn't enough to get 12 turns. Actually can't tell a difference receiving but my SWR was much better with the choke on the EFHW. Think I might try again with some longer coax and an FT-240-43.

I just made a 20m EFHW last night with the cheapest finest 49:1 I could find on Amazon. Going to try it today, then crimp a spade connector on the end and see if I can link another section of wire to make it a 40m EFHW. If I was smart, I would've started with a 10m EFHW and made it a linked 10/20/40, but that's a problem/project for future me.

[WRYZ926]

Linked EFHW antennas are more efficient than one tuned for the lowest band. But a 40m EFHW still works well for 10m, 15m, and 20m. Most of the time you either won't need a tuner or a radio's internal tuner will work.

I built a 80m EFHW and the SWR is 2.0 or less on 80m, 40m, 30m, 20m, 17m, 15m, 12, and 10m.

In @TNFrank case, I would just make it for 10m as he can always turn it into a linked dipole later.

[hxpx]

2 minutes ago, WRYZ926 said:

Linked EFHW antennas are more efficient than one tuned for the lowest band. But a 40m EFHW still works well for 10m, 15m, and 20m. Most of the time you either won't need a tuner or a radio's internal tuner will work.

I built a 80m EFHW and the SWR is 2.0 or less on 80m, 40m, 30m, 20m, 17m, 15m, 12, and 10m.

In @TNFrank case, I would just make it for 10m as he can always turn it into a linked dipole later.

FT-891 doesn't have an internal tuner and the manual says to keep it under 1.5:1 if possible. Figured making a linked wire would be less convenient but better SWR.

I thought the radiation pattern got weird on harmonics - like, it works but you get lobes and weird nulls.

[WRYZ926]

Yes you do get different lobes on higher bands the using an EFHW. But they still work pretty well across multiple bands and why they are popular for POTA.

I would definitely use a linked EFHW if I didn't have a tuner and I was only using the antenna for portable work.  I personally don't want to mess with a linked antenna in a permanent installation.

[hxpx]

34 minutes ago, WRYZ926 said:

Yes you do get different lobes on higher bands the using an EFHW. But they still work pretty well across multiple bands and why they are popular for POTA.

I would definitely use a linked EFHW if I didn't have a tuner and I was only using the antenna for portable work.  I personally don't want to mess with a linked antenna in a permanent installation.

Oh. Yeah, that makes sense. This was meant to be "portable" since the HOA doesn't like permanent antenna installations without approval.

I do use one of my gutters as an end fed random wire. RX isn't as good as the 17' whip I usually use and SWR is okay (1.3 on 20m but 2+ on 40m and 10m) but TX works well and the only visible part is the short wire from my gutter to the unun. Could fix the SWR with a different length of wire between the gutter and the unun but since all I use it for is POTA hunting on 20m, it's good enough for now.

[TNFrank]

Do EFHW's work better closer to horizontal or vertical? If I move my tripod closet it would make the antenna have a steeper slope. 

[WRYZ926]

Most people run them as a sloper.

[TNFrank]

I was looking at it, I've only got about 2' of 550 going from the mast to the wire so moving it closer wouldn't change things much.  I think the EFHW is working just a bit better than the Inverted V so I'll probably run it more.