"Tiger tails" - Are they really worth using?

3 November 2015

Updated 24 January 2016

Something that has been quietly making the rounds in ham radio groups for many years, and now on social media, is this quaint little thing commonly called the "tiger tail", or more specifically the counterpoise. One thing that people never seem to agree on is if it really makes that much of a difference.

As I was working my latest round of antenna tests, I was putting the antenna on my UV-5R, and something clicked. I had been testing my UV-5R as I have always used it over the past year, with a counterpoise wire hanging off of it. Would that little wire really affect the results that much? That leads me to the below tests.

As most of us know, a transmitted signal works best with a resonant antenna specific to that frequency. A resonant antenna typically means the best radiation pattern off the antenna and a low SWR (among other things, I will not go into too much detail). In a way, you can think of an antenna like a normal DC battery, there is a positive and a negative side. In order for electricity, including electromagnetic radio waves, to have a complete path, there needs to be a full "circle" for it to travel with the least amount of resistance. This is typically why dipoles (both horizontal and vertical) as well as ground plane based antennas are typically used the most for almost all bands. For a resonant vertical dipole, it should have a quarter wave going up from center and a quarter wave going down from center, and fed fairly close to center without the two antenna sides touching. Looking at the simple math for a quarter wave, it is 234 divided by Frequency equals length in feet. Since 2m is a shorter wavelength, we can then multiply that answer by 12 to get the length in inches. For example, 234 / 145MHz = 1.614ft x 12 = 19.366 inches. Therefore a resonant 2m 145mhz dipole should have 2 lengths that are approximately 19.366 inches long, one going up, one going down. This should give a total length of approximately 39 inches (taking into account a quarter to half inch space in the middle). To verify the numbers here, feel free to check out the antenna calculator page.

Since we are talking about handheld radios, it is not possible to have a full quarter (over 19 inches) or half wave (19 inches times two) with a handheld that is only approximately 4 inches tall itself. The closest is the Nagoya NA-771 which is 15.6 inches long, but still, this is only the "positive" side of the antenna. What most handheld manufacturers do is have a metal cage or supports around a portion of the main radio body, which is supposed to be the "negative" or ground side of the antenna. The downside is this is a very inefficient way to handle the other half of the signal since most of it is in your hand.

This is where the counterpoise or "tiger tail" ideas came from, positing that the handheld antenna handles the upper portion of the dipole, and the counterpoise handles the bottom portion. But when we're talking about such low power and small radios, does it really make that much of a difference? Until now I had not seen another page actually put this to the test. This does not mean they are not out there, I just personally have not seen any. Most pages mentioning it just claim how it "sounds" or "able to reach a repeater they had not before", but those are opinions with no real proof to back it up. I will be doing the testing and showing the numbers.

Testing method

All tests done with Yaege FC-1 frequency tester, connected to Tram 1185, with 11 feet (3.35m) between radio and Tram antenna. Each test was run minimum 3 times to ensure there was no errant signal interfering, and if anything seemed off, I reset, checked my connections, checked for other signal use by hams in the area, and then restarted. Numbers given in the table are dBm (with 0.5dBm steps) as that is what my frequency counter shows. These numbers cannot be directly compared to other dBm numbers given by other people as every test, location and radio has a different set of variables. What I show as 0.5dBm, someone else may show as 3dBm with their layout. I offer these as a comparison within my own testing environment where I could control as many of the variables as possible.

For testing, I set the radio at its highest power level, which means 4W for the 5R, 8W for the BF-F8HP model and 5W for the OBLTR-8R. I tested only at the center frequency of the (US) ham bands, which would be 146.000 and 435.000. I ran through the tests first using each antenna without it, and then again with it. The counterpoise I am using is a simple 20 gauge copper stranded wire that is 16.5 inches long (it is what I had when I added it a year ago to my 5R, so may as well test using it) with its original plastic coating except at the end. To connect it, I loosen the ring outside of the SMA connector on the radio itself, and then slide the wire under it, tightening that ring back down. This offers a good connection without affecting anything else. Some people use other methods such as electrical rings or the screw at the belt clamp, I have not and likely will not test these since they will be unreliable and will add additional variables such as the connection, hand pressing the transmit plus the belt clamp screw and so on.

Also another unusual coincidence is that the length of my counter poise wire that I made a year ago, also happens to be close to the length of the NA-771 antenna (counterpoise is 16.5", NA771 is 15.6"). This is purely unintentional as I had made that wire at least a month or two before I ever knew about the aftermarket antennas.

Another thing worth noting is this first round of testing relates to transmitted signals (through the antenna and counterpoise). I do have plans to run a different test to see if the "tiger tail" also helps with reception (or not).

TRANSMIT TESTS

UV-5R

Firmware: BFS313

Antenna 146.0 435.0 5R w/ tail -1.5 +0.5 5R no tail -8.0 -0.5 V85 w/ tail +3.5 +0.5 V85 no tail -3.5 +1.0 NA701 w/ tail +3.5 -1.5 NA701 no tail +1.0 -1.0 771 w/ tail +8.0 -7.5 771 no tail +1.5 -7.0

BF-F8HP

Firmware: N5R-319

Note: Stock antenna for F8HP is the V85

Antenna 146.0 435.0 V85 w/ tail +3.0 +1.0 V85 no tail +1.0 -0.5 NA701 w/ tail +6.0 -1.5 NA701 no tail +4.0 -1.5 771 w/ tail +7.0 -6.5 771 no tail +3.5 -7.0

OBLTR-8R

Note: Stock antenna for OBLTR-8R is similar in looks to the Baofeng V85, but may have slightly different insides.

Antenna 146.0 435.0 V85 w/ tail +0.5 -1.0 V85 no tail -1.0 -1.5 NA701 w/ tail +4.0 -4.0 NA701 no tail +2.5 -4.0 771 w/ tail +8.0 -7.5 771 no tail +3.5 -8.5

TRANSMIT RESULTS

The results as shown from the above tables pretty much speaks for itself. YES they do work, and not by just a little, but a lot. One exception is they are not really dual band as I originally thought. You could probably eke out an additional 1 or 2 dBm by using a slightly thicker wire, around 16 or 18 gauge. Since it is a handheld, you do not want a bulky wire hanging off and getting in the way, and the bulkier wires past 14 gauge would not give any additional benefit.

I did not and do not really have much of a way to test it for the receive capability, but from personal use on my 5R, simply adding that wire does help a little with receive, but it is not some magic switch, it is still limited by the height and receive gain of the antenna on the radio itself. I may decide to try a receive test by reversing the antenna connections (Tram 1185 to F8HP, and the various antennas with and without the counterpoise on my frequency tester.

If you have a UHF only model like the BF-888 or the ANILE-8R, then you would need a UHF specific counterpoise, which would be approximately 6.5 inches long. If you primarily use VHF, then a counterpoise in the range of 16 to 19 inches should work wonders. I made another one that was 19 inches long, quickly re-ran a few tests, and there was less than 0.5dBm difference in the VHF band, so anything in the 16 to 19 inch length should work well for VHF. If you use the UV-82X primarily with the 1.25m band (220MHz), then the counterpoise should be approximately 12.5 inches long. For these and other frequencies, feel free to check out the antenna calculator page.

The only time you would not need or want a counterpoise is if you're using the HT with an external antenna like a Tram 1185, a handheld (or mounted) directional yagi or an external antenna on the house. This is because the magnet mount uses the vehicle as its "counterpoise", so having one on the radio itself will likely not have any effect at all. For external antennas on or above the house, they should always be made with their own counterpoise or "negative" ground side, so one would not be needed for the HT in those situations.

Quick 220 MHz test

A quick preliminary test for 220 showed similar gains. Using my UV-82X and a 12.5 inch counterpoise, transmitting at 223.0MHz without it (using stock antenna) showed -15.0dBm, and with the counterpoise (still with stock antenna) at -7.0dBm, an increase of 8dBm.

RECEIVE TESTS

----------

For the receive test, I just did the reverse of the transmit test. On the receive side, the Yaege FC-1 frequency tester had a 16 inch long 12 gauge stranded copper wire counterpoise with a ring terminal under the Baofeng V85 antenna (the one that comes with the official F8HP and 82HP models). For the transmit side, I used the BF-F8HP (without counterpoise) set to 8W transmit power at the center of each amateur band (146.0 and 435.0MHz), connected to the Tram 1185 with 11 feet (3.35m) between frequency tester antenna and Tram antenna. Each test was run minimum 3 times to ensure there was no errant signal interfering, and if anything seemed off, I reset, checked my connections, checked for other signal use by hams in the area, and then restarted. Numbers given in the table are dBm (with 0.5dBm steps) as that is what my frequency counter shows. These numbers cannot be directly compared to other dBm numbers given by other people as every test, location and radio has a different set of variables. What I show as 0.5dBm, someone else may show as 3dBm with their layout. I offer these as a comparison within my own testing environment where I could control as many of the variables as possible.

One question may be why 16 inches instead of closer to the 2m resonant 19 inches? The answer for this is I just happened to have a 16 inch length already cut, AND once you figure in that most handheld radios also have their "cages" as part of the counterpoise "negative" side of the antenna, I figured that could account for approximately 3 inches of counter poise. Granted this is based entirely on what I've learned, and not hard "scientific" evidence, but at least this way I can get direct comparison to what I've been using with my handhelds for over a year now. Also at 16 inches, it makes for a slightly more manageable counterpoise.

I am using the same counterpoise for 2m and 70cm, but I do have plans to make a shorter counterpoise for 70cm frequencies to see if the resonance of the counterpoise really affects the receive (and transmit) signals that much.

Receive test 1 - Basic

Frequency with tail w/out tail 146.000 +2.5 -3.0 435.000 -3.0 -4.5

Receive test 2

Now what about counterpoise plus specific antennas? I decided to do that testing too for the receive side. Transmit side is still the F8HP connected to Tram 1185 at 11 feet away from the frequency tester. Note: Due to minor variations, some of these numbers may differ from the previously tested F8HP numbers due to atmospheric conditions, frequencies in use, and other variables outside of my control. These numbers are only to be compared with each other, not other test results.

Antenna 146.0 435.0 V85 w/ tail +2.5 -3.0 V85 no tail -3.0 -4.5 NA701 w/ tail +5.5 -6.5 NA701 no tail -6.5 -8.0 771 w/ tail +7.0 -6.5 771 no tail +3.0 -7.5

RECEIVE RESULTS

As we can see here, adding the counterpoise also greatly affects the signals received. This is due to the extra counterpoise wire "catching" more of the signal, just as it allows more of the signal to be transmitted. So what this shows is handhelds will definitely take advantage of a counterpoise, on both transmit AND receive. For an analogy, a handheld without a counterpoise is like an antenna on top of the house that is just a single vertical, and no ground plane or lower half to act as the counterpoise.

This results in much lower transmit and receive signal strengths and the transmitted signal being unpredictable without detailed simulations and testing with antenna analyzer software. I have actually run it through the MMANA-GAL basic antenna simulations. Just the signal radiator going up shows minimal gain, SWR through the roof and the Ohms very low (around 4.5 Ohms). Compare it to a simple dipole fed in the middle, which shows much better numbers with higher gain, SWR under control and Ohms closer to 80. With this information, it only makes sense to use a counterpoise, not only for better and stronger signal transmission and reception, but also to help lengthen the life of even the cheapest chinese radio. Since it will not have to compensate for the high SWR and Ohms being so far off, the electronics will last much longer.

As stated before, a counterpoise is only useful when using actual handheld antennas as a portable. A counterpoise will not be needed when using a mobile antenna like a Tram 1185 or Nagoya UT-72.

Finale

That is all for now, feel free to contact me with questions, or if you're on Facebook, check out my Facebook ham radio help page.

Take care and 73s!

Mike

K4ISR

As more blog entries are added, some get moved to the archived blog entries page. As this is a new website, this will probably not need to be done for a month or two.