Questions about antenna gain
Probably the question I get asked most is “what kind of gain do the signal sticks have”, and “why don’t you list gain on the site?” I have answered many people individually, but it comes up often enough that I figured I should probably write up an explanation.
First and foremost, the reason I don’t list the gain of the antenna is that I don’t like to lie to people. I consider it dishonest to give a number which can’t be proven in actual use. Here is the problem with “gain”: gain is a relative term. Literally. Gain is defined as “increase the amount or rate of (something, typically weight or speed)” — in this case, it would be an increase in output, signal strength, etc. Here is the issue, though: it has to be relative to something.
When you transmit, you put out a certain amount of power — if it’s a handheld, that might be 5 watts. If you have an “ideal antenna” then those 5 watts will go out from the radio and nothing will be reflected back to the radio (in a simplified way, this is what SWR is: how much power was radiated vs reflected). However, if you had a theoretically ideal antenna you could have another theoretically ideal antenna which outperformed it in certain cases. This is because there are actually two things to worry about: 1) the power of the radiated signal, and 2) the direction of the radiated signal.
Some antennas will tell you that they are 3dB gain — this means they will have twice the signal strength of some other antenna. If you see 3dB then you should find out what that is in relationship to. I can confidently tell you that you should get at least 15dB gain using my antennas…. compared to using a dummy load.
Finally, a “rubber duck” antenna is able to be short because it makes up for it’s short length by adding a “load” to the antenna — typically a coil at the base which loses some energy to heat in exchange for making the rest of the antenna resonant at the frequency you need. It also changes the radiation pattern, though; in general, only a very very poorly designed “whip” antenna would fail to outperform the rubber duck, but remember that radiation pattern! In some odd cases I’ve seen it happen, and in a car when the “whip” might have to be bent over the duck will likely work better.
So stop yakking and answer the question already!
Anyway, the long and the short of it is that it’s impossible to tell for sure what the “gain” of an antenna is without doing a lot of careful measurement under different circumstances with very expensive equipment — equipment that I don’t have. I can’t calculate the “gain” relative to your stock “rubber duck” antenna because I don’t know the exact characteristics of that antenna. Added to this is the fact that a typical handheld antenna is actually just half of a dipole, and it doesn’t tend to hold still or remain constant relative to things near by that might affect the performance of the antenna — things like cars, houses, trees, fences, other people, your arm, etc.
The dirty truth is that even SWR readings on a handheld antenna may vary as much as 1:1-5:1 depending on what is near, where the handheld sits, how the antenna is mounted, and any number of other factors. (Yes, I’ve measured that). When companies say that their handheld antenna gets 1.5:1 VSWR they are telling you that they managed to find some setup where they could measure that, not that you should actually expect that performance. In my experience, most handheld antennas are actually operating at more like 3:1.
Our antennas work very well — they should work a lot better than the stock antenna on your handheld. If we trust gain figures from other similar commercial antennas we might guess that these are approximately 2dB on 2m, probably 2dB to 3dB compared to an isotropic antenna on 70cm. We could further deduce that these should be about +6dB compared to “typical stock HT antennas”… and just think, with that and $5 you can get a happy meal at McDonalds!
The one thing to note is that some other antennas have a matching section in the base that turns the 70cm function of the antenna into a 5/8 wave. Signal Sticks are 3/4 wave on 70cm, which will tend to only be a little better than a really well made rubber duck.
I hope that answers some questions!
18 thoughts on “What kind of gain do the Signal Sticks have?”
I think a more appropriate question would be, “What kind of looses does your antenna not have.” If SWR is a great indicator of emission efficiency, you could use a twenty five cent Radio Shack light bulb and be fine. Small, cheap and you can use it to find your keys in the dark.
Larry Jacobs – WA7ZBO
I have purchased 3 of your antennas. Wondering what is the max watts they can handle? Could I hook this to a mini mobile @ 25 watts?
You won’t damage the antenna, but at higher power ratings it might start to heat up more than you like — I haven’t tested this extensively. I’d generally look for something more stable for a mini mobile (half wave telescoping, roll up j-pole, etc), but if you try and somehow break the antenna let me know — I’ll replace it for free (lifetime guarantee) and we’ll know there is a limit.
I don’t want to damage one of the antennas. Probably not good to be that close to 25 watts of RF. I have an Ed Fong DB-2 roll up that will handle 50 watts. Better to have the antenna elevated to improve the transmit and receive performance. Your antennas work great, especially when adding a 19 inch counter poise to my HT’s.
How did you make the 19 inch counter poise for you HT’s? How did it attach to the HT itself?
the 19 inch counter-poise can be made in a few different ways, but the easiest / simplest is to just attach a 19″ wire to alligator clips and clip it onto the shield; this is easily done on a BNC antenna, much harder to do with SMA-M or SMA-F. In those cases I usually use a barrel or other connector to help or else construct an antenna without the plastic pieces in order to make testing easier, depending on my goal.
I’ve experimented with making antennas with the counterpoise built in, but haven’t found a reliable enough method to make it worthwhile so far.
Just cut a 19 inch piece of coated wire, strip one end 2 inches and wrap that bare metal around the base of the radio end connector and let dangle. Now you have the other half of a dipole
Can I stop by and pick up one…I commute from Ogden to draper.
I have been known to meet up with people but it’s usually not worth the time for either of us — shipping to anywhere in the US is only $2.66, so you’re not saving a lot of money over just ordering it online.
You could list the gain in dBi or dBd. Then it’s being compared to either a theoretical isotropic antenna or standard half wave dipole. Either way it would give the consumer an apples-to-apples comparison against other antennas which also specify their gain relative to the same theoretical isotropic antenna or standard half wave dipole.
We can certainly calculate what that would be — and I’ve got a friend working on that — but there are so many variables with the way a 1/4 wave HT antenna works in the real world on an HT that it’s *extremely* unlikely that it will be more than a “in an ideal world” type of number that has little bearing on reality.
Of course, that’s what everyone else is reporting, so perhaps we should just roll our eyes and do so as well.
My current estimate which we are trying to verify with Math is that it’s about 2.15dBi, which should be around 4.5dB gain relative to a typical rubber duck. In other words, 0dBd since it’s a quarter wave dipole, essentially.
My Signl Stick does much better than a Diamond antenna as long as the Signal Stick, using my PicoAPRS V3 Tracker from DB1NTO. Hits on a digipeater 4mi away with 1W!
I had antenna bought from you checked by
Old Ham on 269 mfj analyzer told me
This antenna was no better than average or worse
Real bad numbers other hams were getting better numbers on diamonds even HYS China antennas can you please explain what I am seeing here high threes on 2 meter & worse on 70mm. Kind of frikin disappointed
I can well imagine why that would be a little disheartening to see! I get questions like this a lot and I really need to find someone to help me with a youtube video demonstrating some things about analyzing HT antennas such as the signal stick which are completely counter-intuitive to anyone used to using something like the the MFJ 269 analyzer.
The problem you run into is that there is no real ground-plane on an HT antenna — in effect, when you’re using it on a real radio, the counterpoise is your radio and your arm. What that translates into when using an analyzer, though, is that every single analyzer you plug it into will give you slightly (and very meaningfully) different readings for SWR. You’ll also find that if you add any kind of feedline to it you’ll get totally different results as well.
The best way I’ve found to combat that is to use some sort of RF choke — such as a large ferrite — around the base of the antenna to isolate the antenna from the feedline and/or analyzer. Once you do this you’ll get near infinite SWR, since then you have no counterpoise at all, so you need to add about a 19″ wire to the shield.
What gets even weirder, though, is that you can change the “center” frequency where you have the lowest SWR by a significant amount by varying the length of the counterpoise (“tiger tail”) wire.
The moral of this story just adds to what I said above — I’d probably say some of it differently if I were writing it today, but the essence is the same. It’s impossible to exactly model an HT antenna in real life because there are too many variables, so all we can actually do is try to approximate as closely as possible and find a design which works “pretty well” in practice in as many different situations as we can.
As to comparing it with other antennas.. well, keep in mind that the SWR of a 50 ohm resistor is exactly 1:1 =] Better SWR on one antenna vs another when you’re talking about an HT antenna could be:
My recommendation for any HT antenna testing is that you basically ignore the SWR and see how it works in practice.
Hope that helps!
I have some SMA Connector Savers. They fit well and work well by themselves. I hope to be able to solder a wire to the gold plated brass which should take the solder OK, assuming I don’t overheat it and the teflon insulation expands and ruins the connector saver. Or maybe I could devise some sort of clip to attach to the connector saver, probably better idea.
There is some difficulty getting the connector into the SMA connector on the phone. It is a little hard to get enough traction to screw it in, but I was able to get it in there OK.
2 of SMA Adapter SMA Plug to SMA Jack straight – SMA Port Saver
Sold by: EMR Shielding Solutions Product question? Ask Seller
Return eligible through Oct 15, 2019
That does sound like it would probably work for a counterpoise; if it were me, though, I’d probably look for a ring terminal with a 1/4″ inner diameter that you could attach the wire to; that would go around the SMA post on the radio. In the case of SMA-M antenna it should work fine with our antennas, though with a SMA-F antenna you may need something like the “connector saver” you mentioned.
Regardless, good luck!
Thanks. That’s a good idea.