Author Topic: Sorting Out The Pros And Cons of Portable Ham Antennas.  (Read 8306 times)

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Tevin

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Sorting Out The Pros And Cons of Portable Ham Antennas.
« on: February 21, 2015, 09:24:39 PM »
There has been a lot of discussion about assorted "go box" or portable antennas lately.

I got the idea for this post after receiving a few private messages both on this website and elsewhere asking for help with the topic. I thought I would do a "mind dump" and just rattle off some ideas all in one place.

What follows is going to be more of an editorial than a completely technical/factual piece. Antennas are a very complex and sometimes controversial topic, so it's ok if some of you don't agree. This isn't politics or religion. It's all good.

Commercially made portable/backpack antennas (Buddipole, Chameleon, etc) come with a few very consequential tradeoffs. The small size and light weight is the the big selling point for these antennas. What you give up is efficiency. A lot of it. You're going to run high SWR most of the time. For many hams the solution is an antenna tuner. Going that route has important considerations:

1. Antenna tuners add weight and space to your setup, partially negating the "portable" aspect of the antenna that you were attracted by in the first place.
2. Antenna tuners add complexity and are another point of failure. 
3. Antenna tuners work by "lying" to your radio. As far as your rig is concerned the match is awesome. But all you did was move the problem to the other side of the tuner. Antenna tuners do not "fix" inefficient antennas, they only convert them into an acceptable 50Ω load for your transmitter. All the original inefficiencies are still in effect.
4. Antenna tuners are an added expense to what is already a costly option.

The honest truth is that no one would choose this type of antenna but for the light weight and small size. They don't have much else going for them. If that is the main priority for you, then consider one more thing....

Commercially made portable/backpack antennas are like Swiss Army knives: They can do all things sort-of well, but no one thing exceptionally well. You could carve a Thanksgiving turkey with a Swiss Army knife, but would you really want to? You would if you also needed to open cans and turn screws and were allowed just one tool for everything. Portable antennas are like that. Most are multi-band, which is great if you are actually going to use all those bands. But if you tend to operate on the same one or two bands most of the time (in other words, you don't care about the can opener)...the trade is probably not worth it.

Gimmick antennas: Oh my, there are all kinds of goofy loops and curls out there that take up very little space and look like a prop from a cheezy 1960's science fiction movie. All of them work to some degree, but all fall far short on their promises. The less it looks like an antenna, the more suspicious you should be. There are no miracles.

My personal portable gear includes homebrew dipole antennas for 40 and 20 that are adjusted so well, I can run without a tuner and never go above 1.5 SWR anywhere on the phone band. I seldom use other HF bands, so an antenna that is only four feet long and works on 160-6 but has shit SWR doesn't impress me  :o  It does not help that there is a generation of hams out there who have never made a simple dipole nor could they if asked to. The dumbing down of ham radio makes conditions ripe for manufacturers' marketing hustles. I knew more as a Novice 35 years ago than most Extras do now...but that's a topic for another post. 

So ask yourself the question: Do you want a versatile antenna with compromised performance (Swiss Army knife), or a specialized antenna with excellent performance (carving knife)? There is no right or wrong response, but you can set yourself up for a big buzzkill if you choose an antenna without first answering the question. 

Hope this is helpful to someone. Additional discussion and questions always welcome.









spacecase0

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Re: Sorting Out The Pros And Cons of Portable Ham Antennas.
« Reply #1 on: February 22, 2015, 03:18:50 AM »
I have tried all kinds of portable antennas,
the first one was the super antenna http://www.amazon.com/dp/B00KU1VMFG
yes it works, no tuner needed, but with the ft-817 it works way better if you have one,
you tune the antenna as well as you can first and then use the tuner to clean up that last bit
if you don't, you end up with only 3W into a not that efficient antenna

having not found the ideal portable antenna I got more of them
next was a 40M and 80M vertical antenna with a BNC connector on it
kind of like a rubber duck antenna for your HT,
http://www.mfjenterprises.com/Product.php?productid=MFJ-1840T
http://www.mfjenterprises.com/Product.php?productid=MFJ-1880T
they do work, just not that well, and the 80M one is likely almost totally pointless
and are tunable fine enough so that you don't need a tuner,
having a stiff enough ground helps them lots,
but by the time you unrolled enough wire to get you the ground you need, why not just use a dipole ?
if you have a nice fence to clip off to helps that issue
but still not ideal in most ways

so I built a few small antennas looking for something better,
they did not do well at all, but then I did not try super hard either

next try was a quite simple system
it does use a tuner, the MFJ-16010 http://www.mfjenterprises.com/Product.php?productid=MFJ-16010
and then a 25 foot wire with string on the end as my insulator
a banana plug is used into the SO-239 connector, you can't run even 2 inches of coax if you want it to work,
my ft-817 and ft-857 have enough of a built in SWR meter to tune it
it works way better than I would have thought when I bought it
I got it due to being tiny light and cheap (or at least it was when I got it)
how well it works on 160M was just quite amazing as I was not expecting it to work at all

if I were getting an antenna now for the same low power radio, it would be a dipole
http://www.mfjenterprises.com/Product.php?productid=MFJ-1774B


Tempstar

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Re: Sorting Out The Pros And Cons of Portable Ham Antennas.
« Reply #2 on: February 22, 2015, 04:33:54 AM »
Great job Tev. It's  what I've preached for years. If it isn't less than 2.0 SWR before using the tuner, kiss most of the radiated power goodbye.
"Preparedness is a lot more than just buying stuff"

spacecase0

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Re: Sorting Out The Pros And Cons of Portable Ham Antennas.
« Reply #3 on: February 22, 2015, 02:20:39 PM »
Great job Tev. It's  what I've preached for years. If it isn't less than 2.0 SWR before using the tuner, kiss most of the radiated power goodbye.
also a big coil at the base of the antenna can be almost as bad as the tuner

DragoSapien

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Re: Sorting Out The Pros And Cons of Portable Ham Antennas.
« Reply #4 on: February 22, 2015, 05:46:25 PM »
Some of you big time hams on this site are the reason why im here and not at QRZ or eham. Most of us didnt get into ham radio because of the hobby. It was to have a way to communicate and to hear news from the out side after SHTF. I had no idea that ham radio was so complicated. UHF/VHF is no big deal, but HF is a whole new world for me. Asking questions here like I have wont go over very well at those other sites. Iv tried and they dont like preppers.  As a prepper, most of them buy the radio and everything else needed and stick it in there shelter. I find my self not being able to do that. Im actually getting into the hobby more and more. ARES, Skywarn, are just some of the things iv gotten into now. So you can count on me to be asking a butt load more questions to learn what you mature hams know.

Thanks guys for setting me straight about things I thought I knew about radios.  LOL.  I learn something every time I get on here.

Tevin

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Re: Sorting Out The Pros And Cons of Portable Ham Antennas.
« Reply #5 on: February 22, 2015, 09:02:38 PM »
also a big coil at the base of the antenna can be almost as bad as the tuner

You are correct that coils are "almost" as bad, but not for the same reason antenna tuners are.

A coil, no matter where it's located, is there to make the antenna's electrical length greater than its physical length. It's a deliberately-added component, and  when properly engineered, the negative effect is quite small compared to the benefits. It's how they get 80 meters worth of radio wave into 20 meters of space. Coils put the tri in tribander.

Antenna tuners, on the other hand, are not part of a carefully designed system. They are used to make a radio work with what would otherwise be an unacceptable load. With a few rare exceptions, adding an antenna tuner is, in essence, the same as admitting your antenna sucks. That is one reason why I don't like the commercially made deals like the Buddipole. If you want an antenna that fits in a backpack and on its own will do no better than a 1.8 SWR, I'll throw something together and sell it to you for a lot less than what those glorified rubber ducks cost. 

I know you knew all this spacecase0. I'm just adding background for the benefit of others.

DragoSapien: I've said this many times already but it's worth drilling home again: Ham radio has a low barrier to entry, but the learning curve is quite steep once you are in the door. It's easy to feel overloaded, but don't sweat it. Most of the technical answers that seem to come so easy to some here are the result of years and in many cases decades of practice and experience (and failure!). So don't freak out if you are relatively new and feel in over your head.
« Last Edit: February 23, 2015, 07:38:47 PM by Tevin »

XJP5

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Re: Sorting Out The Pros And Cons of Portable Ham Antennas.
« Reply #6 on: February 23, 2015, 04:59:06 PM »
Excellent advice Tevin, thank you.  :)

AD

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Re: Sorting Out The Pros And Cons of Portable Ham Antennas.
« Reply #7 on: February 23, 2015, 05:45:28 PM »
DS

Thats why I started this site. It happened when AA on another site started writing Going Home a chapter at a time.  I contacted him via PM and suggested he put ham into the book and gave him suggestions for that.

One of the guys on that forum, Tex had the cell towers blow up after a strong CME in Jan 2012 and suggested that all preppers should really look into ham radio for comms. 

I got tons of emails and PMs and a week later this site was born.

I got my license in 2011 after getting into prepping. 

I have an Amateur Extra license for two reasons
1. I like DX but with a KF7XXX call, 100 watts and hidden end fedz wires in pine trees in my front yard to hide them from the HOA, QSOs went uncompleted due to bad conditions, low power and a LOOONNNGG call.  So I got my extra to get a XX1X call sign to be easier to cmplete a QSO.

2. Being a mechanical engineer, i like the challange of studying and passing the exam.

I by no means know even a small portion of the technology like Tev, BT and others here and would be called "an appliance operator" by many, but I could care less about what others think.  I am learning everyday and my main reason for being here is to be able to communicate in any situations moving forward.

I still work hard to get people into the "sport".  This weekend we had a science fair in the city where I am on the CERT commo team.  Most of the guys in the CERT group have Tech privileges and have never worked HF before. 

So this Sat we sent up a 857d with a very marginal comet rotating dipole at the staggering height of 8 feet off the ground. So calling CQ our first contact was into Vancouver BC where i supplied the recieving end of a GOTA(get on the air) for a 10 yo young lady and answered all of the standard questions:
whats your Fav color, do you have a pet, whats the temp.....

Then turned the mike over the the guys in the group and most everyone gave it a shot.  Now they are interested in learning more and will study for their General. 
The only dumb question is the one that did not get asked!!

Tempstar

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Re: Sorting Out The Pros And Cons of Portable Ham Antennas.
« Reply #8 on: February 24, 2015, 03:55:57 AM »
Great post AD. You are doing what the true spirit of Amateur Radio involves: Involving others.
"Preparedness is a lot more than just buying stuff"

spacecase0

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Re: Sorting Out The Pros And Cons of Portable Ham Antennas.
« Reply #9 on: February 24, 2015, 12:14:06 PM »
I know you knew all this spacecase0. I'm just adding background for the benefit of others.
you are correct,
I really appreciate that you added all the details for others,
lately I am starting to see that I am not good at telling others the "why" behind things unless they ask,
it is a critical thing when teaching others, I am working on it, but clearly not getting that far