HT antenna SWR

[WREJ796]

Short version at the end.

 

Background, I recently got a mag-mount 1/4 wave antenna for my vehicle and a "slim jim" antenna to use at home or camping. Performance of both is great and I'm enjoying the increased range and improved audio.

 

However, as I was researching antennas I kept seeing people refer to tuning antennas for best SWR, which led me down the path to get a SWR/power meter so I could check my antennas. Not wanting to break the bank I went with this relatively inexpensive one that was recommended (Youtube, Reddit, blogs, etc):

 

Surecom SW-33 Mark II VHF/UHF SWR/Power Meter

https://www.amazon.com/dp/B075H8FDDR

 

I used it to check SWR at 462/467MHz on the slim jim (1.1/1.2) and 1/4 wave (1.4/1.5) which seemed to be reasonable. I was curious to see if any of my HTs had one of the notoriously bad rubber duck antennas, so I checked all 4 and got SWRs from 3.0 to 8.9 depending on the frequency. I would say it's a bad meter except for the reasonable readings on the 1/4 wave and slim jim, so if it's not a bad meter why would the SWR be so high on my HT antennas?

 

The main difference is that my HT antennas are all SMA-F while both externals are BNC-M, so I had to use a different adapter. Is it a bad connection on the SMA adapter? If so any tips to get an accurate reading on my HT antennas?

 

 

Short version: I checked the SWR on my HT antennas and got incredibly high (3.0 to 8.9) readings compared to mobile and base antennas. Wondering if those readings could be accurate or not, and if not what the most likely issue is. 

[mpoole]

I'm using a SW-33 MarkII that has SMA-F fittings.  I've check a GMRS Nagoya antenna that comes in at 4.5 on my hand-held.  I've used the same meter to check a home made ground plain antenna tuned for 151MHz that tested at 1.06.  I really think most of the hand-held rubber ducky antennas are pretty bad.   I also took a Nagoya-771 that read at 3.5 and cut it down to get a 1.6 on GMRS channels but I had to cut it down to 1 cm......kind of ridiculous.

[tweiss3]

Short version at the end.

 

Background, I recently got a mag-mount 1/4 wave antenna for my vehicle and a "slim jim" antenna to use at home or camping. Performance of both is great and I'm enjoying the increased range and improved audio.

 

However, as I was researching antennas I kept seeing people refer to tuning antennas for best SWR, which led me down the path to get a SWR/power meter so I could check my antennas. Not wanting to break the bank I went with this relatively inexpensive one that was recommended (Youtube, Reddit, blogs, etc):

 

Surecom SW-33 Mark II VHF/UHF SWR/Power Meter

https://www.amazon.com/dp/B075H8FDDR

 

I used it to check SWR at 462/467MHz on the slim jim (1.1/1.2) and 1/4 wave (1.4/1.5) which seemed to be reasonable. I was curious to see if any of my HTs had one of the notoriously bad rubber duck antennas, so I checked all 4 and got SWRs from 3.0 to 8.9 depending on the frequency. I would say it's a bad meter except for the reasonable readings on the 1/4 wave and slim jim, so if it's not a bad meter why would the SWR be so high on my HT antennas?

 

The main difference is that my HT antennas are all SMA-F while both externals are BNC-M, so I had to use a different adapter. Is it a bad connection on the SMA adapter? If so any tips to get an accurate reading on my HT antennas?

 

 

Short version: I checked the SWR on my HT antennas and got incredibly high (3.0 to 8.9) readings compared to mobile and base antennas. Wondering if those readings could be accurate or not, and if not what the most likely issue is.

You have to use the metal plate provided because inserting the meter between the antenna and HT breaks half the antenna. On an HT, the body acts as half the antenna system (ground plane).

[WREJ796]

You have to use the metal plate provided because inserting the meter between the antenna and HT breaks half the antenna. On an HT, the body acts as half the antenna system (ground plane).

 

Can you expand on this? It didn't come with a metal plate, just a handful of antenna adapters and a 5W dummy load. If there's a technique to getting an accurate SWR reading that would be good to know.

 

I also realize I didn't list the HTs:

• Kenwood TK-360G (stock duck and a 3" Kenwood stubby)
• BTech GMRS-V1 (stock duck and NA-701c)
• Wouxun KG-805g (stock duck)

[axorlov]

I also have Surecom SW-33 and I do not trust it on UHF. It disagrees with my better meter Diamond SX-600. And mine also did not come with metal plate. Maybe yours works better on UHF...

However, even when using metal plate to create a groundplane and decouple the body of the radio from the antenna, you are creating a different antenna, not the one that is normally attached to HT and uses your body as a coupled ground. Just inserting Surecom between radio and antenna also not going to work for the same reason: it's a different antenna now. I do not know of a way to measure SWR or power to the HT antenna.

[axorlov]

One more note about Surecom SW-33. To check if I can possibly trust it, I measure forward power into dummy load on UHF. The radio supposed to be 4W. The SX-600 shows something like 3.8W, and SW-33 shows 2.3. On VHF both SW-33 and SX-600 mostly agree with each other. So, I angrily threw SW-33 in the deepest darkest corner of my cabinet and forgot that it exists.

[tweiss3]

The Surecom 102 comes with a plate: https://www.409shop.com/thumb/phpThumb.php?src=../uplimg/mb100556_4b6eced6b53f86636eddd2f77f010506_mainpic.img&w=350&h=350&bg=FFFFFF&fltr[]=usm|80|0.5|3

Its is attached on the antenna side: https://www.409shop.com/thumb/phpThumb.php?src=../uplimg/mb100556_5e8455bf70241d5788b5403472e8102c_addpic1.img&w=700&fltr[]=usm|80|0.5|3

[mbrun]

Measuring the SWR of quarter-wave HT antennas is incredibly difficult (if not practically impossible) to do by the average person because they generally lack the means to measure the antenna under the exact same conditions the antenna operates when mounted directly to the radio. Also, quarter-wave antennas are dramatically affected by the elevation above ground, the radio to human interface and other environmental factors.

 

Half-wave rubber ducks are a different story. They are not affected by these things nearly as dramatically in my experience.

 

There is a load of discussion on this very topic in many of the amateur radio forums available on the net. Only some of the most technically savvy have had the will and skill to overcome the obstacle and build test jigs to simulate the same conditions. I am only now just starting to dabble with this. One of the most common talked about solution includes sacrificing an existing HT to use as a component of the test jig.

 

While we all like to talk about achieving a low SWR, a low SWR on a rubber duck is not as important as achieving a low SWR on a remote antenna (mobile, base, etc...) because you do not have the cable (aka feed line) losses eating up the power reflected back by the antenna. Instead, when you have an antenna connected directly to the radio, even when it is a less than perfect antenna, the highest majority of the transmitter power will still be radiated.

 

From all my reading to date I have learned that the most effective way to contrast the performance of HT antennas is to use a field strength meter instead of an SWR meter. By contrasting the field strength of one rubber duck against another under identical test conditions you will be able to measurably determine which performs better.

 

BTW, I too own a SureCom meter. Mine did come with a ground plane (GP) plate. All my 1/4 antennas perform poorly (from SWR perspective) without the GP (I have experienced as high as 12:1). With it, the values fall down into a range less than 3:1 on all of them. In contrast, the GP has negligible affect on the longer wavelength antennas which regularly seem to measure well below 2:1.

 

Michael

WRHS965

KE8PLM

 

 

Short version: I checked the SWR on my HT antennas and got incredibly high (3.0 to 8.9) readings compared to mobile and base antennas. Wondering if those readings could be accurate or not, and if not what the most likely issue is.

 

Sent from my iPad using Tapatalk

[Lscott]

Measuring the SWR of quarter-wave HT antennas is incredibly difficult (if not practically impossible) to do by the average person because they generally lack the means to measure the antenna under the exact same conditions the antenna operates when mounted directly to the radio. Also, quarter-wave antennas are dramatically affected by the elevation above ground, the radio to human interface and other environmental factors.

 

Half-wave rubber ducks are a different story. They are not affected by these things nearly as dramatically in my experience.

 

There is a load of discussion on this very topic in many of the amateur radio forums available on the net. Only some of the most technically savvy have had the will and skill to overcome the obstacle and build test jigs to simulate the same conditions. I am only now just starting to dabble with this. One of the most common talked about solution includes sacrificing an existing HT to use as a component of the test jig.

 

While we all like to talk about achieving a low SWR, a low SWR on a rubber duck is not as important as achieving a low SWR on a remote antenna (mobile, base, etc...) because you do not have the cable (aka feed line) losses eating up the power reflected back by the antenna. Instead, when you have an antenna connected directly to the radio, even when it is a less than perfect antenna, the highest majority of the transmitter power will still be radiated.

 

From all my reading to date I have learned that the most effective way to contrast the performance of HT antennas is to use a field strength meter instead of an SWR meter. By contrasting the field strength of one rubber duck against another under identical test conditions you will be able to measurably determine which performs better.

 

BTW, I too own a SureCom meter. Mine did come with a ground plane (GP) plate. All my 1/4 antennas perform poorly (from SWR perspective) without the GP (I have experienced as high as 12:1). With it, the values fall down into a range less than 3:1 on all of them. In contrast, the GP has negligible affect on the longer wavelength antennas which regularly seem to measure well below 2:1.

 

Michael

WRHS965

KE8PLM

 

 

 

 

Sent from my iPad using Tapatalk

You’re right about testing HT antennas. It’s very difficult to get an accurate measurement for the SWR. I know because I tested a bunch I have in my collection. The only thing that seemed fairly consistent were the UHF antennas. 

 

At 450 to 470 MHz they only need to be about 6 inches long for a full 1/4 wave, thus you don’t have a real lossy helical wound coil found in the typically stubby VHF designs. Further on a decent sized radio the internal metal chassis provide a fairly good ground plane. When you look at the really tiny shirt pocket radios that isn’t so true.

 

One other reason to stay away from the tiny radios had to do with the heat sinking of the final power amplifier stage. Using them for more that a few percent duty cycle the make wonderful hand warmers. One Ham wrote about destroying his output power stage more than once when running full power at more that the manufactures recommended duty cycle on transmit.

 

On H PO T antennas testing one guy made an attempt to replicate the conditions the antenna sees when on a radio. There were some problems with his test jig that are pointed out in the comments.

https://reflector.sota.org.uk/t/antenna-testing-jig-swr/14791

[1URFE57]

Short version at the end.

 

Background, I recently got a mag-mount 1/4 wave antenna for my vehicle and a "slim jim" antenna to use at home or camping. Performance of both is great and I'm enjoying the increased range and improved audio.

 

However, as I was researching antennas I kept seeing people refer to tuning antennas for best SWR, which led me down the path to get a SWR/power meter so I could check my antennas. Not wanting to break the bank I went with this relatively inexpensive one that was recommended (Youtube, Reddit, blogs, etc):

 

Surecom SW-33 Mark II VHF/UHF SWR/Power Meter

https://www.amazon.com/dp/B075H8FDDR

 

I used it to check SWR at 462/467MHz on the slim jim (1.1/1.2) and 1/4 wave (1.4/1.5) which seemed to be reasonable. I was curious to see if any of my HTs had one of the notoriously bad rubber duck antennas, so I checked all 4 and got SWRs from 3.0 to 8.9 depending on the frequency. I would say it's a bad meter except for the reasonable readings on the 1/4 wave and slim jim, so if it's not a bad meter why would the SWR be so high on my HT antennas?

 

The main difference is that my HT antennas are all SMA-F while both externals are BNC-M, so I had to use a different adapter. Is it a bad connection on the SMA adapter? If so any tips to get an accurate reading on my HT antennas?

 

 

Short version: I checked the SWR on my HT antennas and got incredibly high (3.0 to 8.9) readings compared to mobile and base antennas. Wondering if those readings could be accurate or not, and if not what the most likely issue is. 

It's normal to get a low reading on your mobile setup and base antenna setup since your measuring it with coax in between the antenna and the meter. I remember before that its advisable to use a length of coax everytime doing some measurement to get accurate reading.

[WREJ796]

Thanks for all the feedback! Sounds like I just can't accurately measure HT antennas, which is fine since I didn't really expect to (I just thought it would be nice).

 

This does bring up a related question though. I've seen quite a few videos and articles describing how they cut down a GMRS 1/2 wave HT antenna until they hit the perfect SWR. Often they're cutting it down to just an inch or two long. Is that a misguided effort based on false SWR readings? I'm clearly no RF engineer, but I thought the physical or electrical length of the antenna had to be at least 1/4 wave to be effective. How can a 1 inch antenna be better than the stock 6" duck?  

[Lscott]

Thanks for all the feedback! Sounds like I just can't accurately measure HT antennas, which is fine since I didn't really expect to (I just thought it would be nice).

 

This does bring up a related question though. I've seen quite a few videos and articles describing how they cut down a GMRS 1/2 wave HT antenna until they hit the perfect SWR. Often they're cutting it down to just an inch or two long. Is that a misguided effort based on false SWR readings? I'm clearly no RF engineer, but I thought the physical or electrical length of the antenna had to be at least 1/4 wave to be effective. How can a 1 inch antenna be better than the stock 6" duck?  

If you don't have (1) the right equipment and test jigs to make accurate measurements and (2) the experience/expertise to do this then I recommend you don't try it.

 

Your typical HT antenna is a 1/4 wave long without internal loading coils. For GMRS frequencies the antenna should be somewhere around 6 inches long without any loading coils. So if somebody cut one down to 1 or 2 inches they very likely screwed up the measurement and or the test jig was very seriously miss designed.

 

I have seen "special" 1 or 2 inch long UHF antennas. They have a construction where they have a build in loading coil to provide the inductance lost due to the antenna being shorten. These antennas are VERY lossy and are likely not much better than a dummy load screwed on to the radio.

[wayoverthere]

I just want to say I greatly appreciate the level of information here compared to some other places online.

 

A similar topic came up related to someone measuring swr on HT antennas, and while there was a LOT of "you're doing it wrong" posts, even the long winded ones blathering about needing better equipment gave zero hint as to WHY what was being done was the wrong way to do it.

[axorlov]

Thanks for all the feedback! Sounds like I just can't accurately measure HT antennas, which is fine since I didn't really expect to (I just thought it would be nice).

 

This does bring up a related question though. I've seen quite a few videos and articles describing how they cut down a GMRS 1/2 wave HT antenna until they hit the perfect SWR. Often they're cutting it down to just an inch or two long. Is that a misguided effort based on false SWR readings? I'm clearly no RF engineer, but I thought the physical or electrical length of the antenna had to be at least 1/4 wave to be effective. How can a 1 inch antenna be better than the stock 6" duck?  

HT antenna - hell NO! Totally misguided.

Mobile antenna on the roof your car or maybe base antenna on the top of your house - yes, techniques involving SWR meter and/or power meter might make sense. Beware of people who do not know what they are talking about. Nowadays anyone can start a youtube channel filled with anything. "Do your research!" Lol!

 

Also consider that good SWR does not mean a good, efficient antenna. Dummy load (from a reputable manufacturer) has a perfect SWR.