Tuning Your Antenna
Tuning your antenna to be resonant on a particular band or bands is an important factor in ham radio operation. Yeah you can have a tuner with you and for some antennas you will need to have a tuner as they will not be tunable otherwise like the Chameleon MPAS 2.0 for instance.
If you have to built an end fed half wave (EFHW) antenna, which are my preferred antennas in the field hands down, then you will need to make adjustments in order for it to give you the best performance. The antennas I primarily use have a 49:1 Unun with a capacitor attached to the antenna. Examples of this are the KM4ACK antenna kit, the K6ARK Antenna Kit, The Packtenna EFHW Mini, etc. The Spark plug antenna which I have done a review on in the past are made with 64:1 Unun’s rather than 49:1. Don’t get me lying about what the difference between a 49:1 and a 64:1 is. I admit it, I don’t know. What I do know is how to tune them and make them work and get a ton of contacts during my POTA outings.
Depending on the antenna you can usually get by with a starting length of wire around 66 feet long and then adjust it accordingly. Some EFHW antennas will be able to be resonant on 40, 20, 15 & 10 meters from a single wire. Sometimes you may have to have different length wires for various bands and/or traps built in to the length of wire to be able to reach the different bands. This will be circumstantial depending on the antenna you choose. The manufacturer will have instructions or at the least notes on what the capabilities are of the antenna and the best practices for you to get it to work for you.
Antenna Analyzers
In order to tune an antenna and be free of automatic tuners, it is a good idea to make the investment in a reliable antenna analyzer. There are tons of analyzers on the market, but by far my preference is the RigExpert line. These are reliable and accurate analyzers/tuners that are easy to read and have multiple functions that can help you with tuning your antennas and get you on the air fast.
I DO NOT suggest buying a cheapy analyzer, but that is my opinion. Get what you can afford or save up and get what you want. The RigExpert runs between $300 – $1000 depending on model and features, etc. Find them HERE
Other options are analyzers by MFJ or the NANOVNA line.
Some radios have a built in SWR Meter...
All is not lost if you don’t have the cash to spend on a Rigexpert meter. Many radios have an SWR meter in them. How informative that meter will be will depend on the make and model. In the example here you see the SWR meter on my Icom IC-705. This meter allows me to set a frequency and it will allow me to see above and below my chosen frequency and give me an accurate reading based on how my radio is reacting to the antenna’s resonance.
This can be a very handy tool to have. Ultimately you care more about what the radio says about your antenna than the analyzer. The analyzer will get you close, but the radio has the final say.
Should You Chase SWR?
To a point, absolutely! Should you stress out about it if you can not get a perfect 1:1 match? ABSOLUTELY NOT! Get it as close as you can or to what you consider to be an acceptable SWR and just go enjoy your radio!
It is very easy to chase that SWR and drive yourself nuts trying to get the perfect match….most of the time it will not happen, so get over it now and find what is acceptable to you.
So what is acceptable SWR?
That depends on you. For me, I am happy with anything from 1.10:1 – 1.25:1. I find that to be my happy sweet spot. You will have minor loss if it is not a perfect 1:1, but who cares??? Get it close and go play radio. Stressing out about SWR and trying to get it perfect is only going to frustrate you. Don’t do that!
Where to tune for the Band(s)
My preference is to tune my antennas (keeping in mind I do a lot of POTA a.k.a. Parks on the Air) to the middle of the General portion of the band. In HF and doing POTA, you will get more contacts in the General area because there are more Generals than Extras, so it makes sense to go where your target audience is.
Below I have a chart for the main bands I use which are 40, 20, 17, 15, 12 & 10 Meters. I am basing this off my DX Commander Expedition antenna which is what I use in the field most of the time unless I am in a hurry and do not want to go through setting it up, in which case I will use one of the many EFHW antennas I have in my arsenal. I am going to list the mid band frequencies for both General (G) & Extra (E)
MidBand Phone (Voice) Divided by General or Extra
40 Meters – 7.237 (G) 7.212 (E) EFHW Wire Length 64.66ft*
20 Meters – 14.287 (G) 14.262 (E) EFHW Wire Length 32.75ft*
17 Meters – 18.139 (ALL) EFHW Wire Length 25.80ft*
15 Meters – 21.362 (G) 21.325 (E) EFHW Wire Length 21.91ft*
12 Meters – 24.960 (ALL) EFHW Wire Length 18.75ft*
10 Meters – 29.000 (ALL) EFHW Wire Length 16.14ft*
*Lengths are approximate. These calculations are based on center of the General Portion of the bands.
Make your initial wire length a bit longer and cut as needed until you reach your target SWR
The following formula is used to calculate the length of an End-Fed Half-Wave (EFHW) antenna.
Length of wire in feet = 468/frequency
In Conclusion...
Tuning your antenna can be fun, or you can make it frustrating. When I first started out and didn’t fully understand the whole antenna tuning thing, it was frustrating. I had no one to rely on to ask questions for quite a while and when I did ask a question I got a ton of different answers. I want to give you the straight DOPE on tuning your antenna and make it as easy as possible. I may be missing some of the technical stuff that others might deem important, but in the end ALL of my antennas work and they all work very well for my needs.
Things you should take away from this page…
- Find an antenna that interests you whether it is a kit or prebuilt antenna and buy it.
- If the manufacturer has instructions or notes on best practices, read them and follow them. This could be best wire lengths to start with, etc.
- Get a good quality analyzer to tune your antenna and make it resonant. You only have to perform this task once and your antenna will work forever.
- Tune to the center of the General portion of the band.
- Get the SWR down as low as you can but DO NOT stress and hyperfocus on it if it is not perfect…it will NEVER be perfect 97% of the time.
- Go play radio and have fun!
- Reach out to the many ham radio Youtube channels out there. There is also a Discord server (Toads <—LINK) that you can join and ask questions and get reliable help from any time you want.