Correct or recommendations for an antenna

[1977Hahn]

I need recommendations for an antenna I have purchased three of them and 2 of them give me an SWR reading of 2.4 and the third gives me a reading of 1.9 the radio manufacturer wants to see 1.5 or less. and recommendations I will heed 

Thanks  

[mbrun]

What specific antennas do you have. Model number’s and links to manufacturer data please.


Michael
WRHS965
KE8PLM

[WyoJoe]

I think a lot more information is needed in order to answer your question.

First of all, there is no mention of your intended use for the antenna.

Second, there's no mention of what type of radio you're wanting to use it with.

Third, there is no useful information given about the antennas you currently have.

SWR readings are relative to the antenna and the radio you're using it with. It is not an "across the board" value. It very much depends on the frequency at which the radio is transmitting.

Please provide more information, or go back and read through the threads about antennas to see what recommendations have already been made.

[wayoverthere]

Based on his other threads, he's likely working with the BTech gmrs 50x1...speaking from experience, I'll hazard a guess that the 2.5 are dual band ham antennas, as that's about what mine showed.

More info on the antennas and the intended use (base? Mobile?) will definitely help with suggestions on whether they can be tuned to something usable for gmrs, or if other options should be  aside from that, I know there's a lot of threads in this section of the forum, search terms like "base antenna" or "mobile antenna" may help find situations similar to yours to give some better focused ideas.

[1977Hahn]

I am sorry for the lack of information as I am fairly new to this grms world but yes WAYOVERTHERE is correct I am using a BTECH GMRS 50X1 the Antennas I have used were all purchased from amazon This is the last one UAYESOK VHF UHF NMO Antenna L-Bracket Vehicle Radio Antenna Roof NMO Mount Dual Band 144/430MHz NMO Antenna W/13ft/4M RG58 Coax Cable this had an SWR of 2.5 , Bingfu Vehicle Ham Radio Mobile Radio Antenna Dual Band VHF UHF 136-174MHz 400-470MHz Amateur Radio Low Profile NMO Mount Antenna for Car Truck Ham Radio Mobile Radio Two Way Radio Marine VHF Radio This one was 1.9 and lastly YS TCJ-N1 Dual Band NMO 144Mhz/430Mhz Mobile FM Transceiver 2M/70cm Antenna with 13 ft RG58 Coax Cable NMO to UHF PL259 Connector for Yaesu Kenwood HYT Vertex Icom Mobile Radios swr 2.5  

Last night I looked at the Tram 1180 Dual Band NMO Mount Antenna (144-148/430-450 MHz)

[1977Hahn]

Is there anything else beside the Antenna that can cause High SWR ? Wayoverthere you said most likely the ones I was using duel band ant. which is true do you think using a strickly UHF ant is a better Idea ? 

[1977Hahn]

I am transmitting on 467.725 I hope that help but I am finding most duel band only are rated to 450hz 

[wayoverthere]

8 hours ago, 1977Hahn said:

Is there anything else beside the Antenna that can cause High SWR ? Wayoverthere you said most likely the ones I was using duel band ant. which is true do you think using a strickly UHF ant is a better Idea ? 

Problems with the cable can cause high swr as well, but looking at those antennas, they don't look like a good match for gmrs frequencies.  Dual band, in itself, isn't an issue, but with the way 2m and 70cm relate, an antenna that's good in the 2m ham band tends to also fit well with 70cm (430-450 mhz) Unfortunately, this is a lower range than we need for gmrs.

The bingfu is a wider frequency range (that stretches up to 470), hence that being the better of the three. What you're really aiming for is 460-470 mhz. If you want good to go out of the box, it's hard to go wrong with Midland (https://www.amazon.com/Midland-Antenna-Durable-Connection-MicroMobile/dp/B084BPXNC5/ ) though it requires a separate mount.

Ideally, if you can still return them, I'd go that route, and look for something better suited to gmrs. Laird 1/4 wave for 450-470 are very inexpensive (around $10) but do require a mount with a good ground plane.

If you're past the return period, a couple of those you linked (the straight whips, first and last I believe) look like they could be cut to be tune them for gmrs; its a usually a matter of loosening 2 screws holding the whip to the mount and taking a little off the bottom of the whip. (Grinding might be better to get there slowly without overdoing it). You could also check with a radio shop for what they might charge, as they'll have the equipment needed, both for the cutting and measuring the antenna performance.

For a couple other suggestions (both require a nmo mount), I've used this browning on my truck, and with it's wide range (406-490) it's played well for both 70cm and gmrs, with a swr 1.2 or less. https://www.amazon.com/Browning-406MHz-490MHz-5-5dBd-Mobile-Antenna/dp/B00TY2KP5K/  the downside is size, at 35"

On the smaller side (~13"), others have used the https://www.amazon.com/Browning-450MHz-470MHz-3dBd-Mobile-Antenna/dp/B00IDTJ2EA/ with good results, though that one also may prefer a little trimming to be perfect for gmrs (per the reviews).

That said, Ive had an antenna that said it would require trimming, but when measured was already really good so I left it alone.

[wayoverthere]

5 hours ago, wayoverthere said:

 Dual band, in itself, isn't an issue, but with the way 2m and 70cm relate, an antenna that's good in the 2m ham band tends to also

small expansion on this point; there are a few dual band antennas focused on the commercial/MURS end of VHF that are a decent match for GMRS as well.  I have (but haven't tested) a Comet 2x4SR nmo that is supposed to play well with MURS, 2m, 70cm, and GMRS, but trades a little bit of a gain for the wider range.  this again requires a nmo mount of your choice, and it's on the long side (~3ft).  it DOES fold over, though, and there is a spring kit available to give it a little more flexibility.

[1977Hahn]

WAYOVERTHERE

I just ordered the Midland antenna 

[1977Hahn]

I want to thank WAYOVERTHERE for the recommendation of the Midland Micro Mobile Antenna my SWR is now at 1.2 on the above frequency.

Thank you again you saved me!! 

[Lscott]

On 10/3/2021 at 6:28 PM, wayoverthere said:

small expansion on this point; there are a few dual band antennas focused on the commercial/MURS end of VHF that are a decent match for GMRS as well.  I have (but haven't tested) a Comet 2x4SR nmo that is supposed to play well with MURS, 2m, 70cm, and GMRS, but trades a little bit of a gain for the wider range.  this again requires a nmo mount of your choice, and it's on the long side (~3ft).  it DOES fold over, though, and there is a spring kit available to give it a little more flexibility.

I have one of the 2x4SR antennas, and a buddy here at work put one on his pickup truck using a lip mount on the front hood near the roof pillar. They work OK, but being a 5/8 wave design you need a REALLY good ground plane.

I did an SWR scan using a RigExpert AA-1000 and downloaded the data to a CAD package for plotting. As promised the SWR was under 2:1 around the GMRS frequencies and very surprisingly very low on the MURS frequencies. 

https://rigexpert.com/products/antenna-analyzers/aa-1000/

The antenna is somewhat sensitive to mounting location even with a good ground plane. If you want one antenna to cover Ham and GMRS its a good option.

[OldRadioGuy]

It's very easy to make a mobile type antenna with low SWR at these frequencies where no "tricks" are needed to make the antenna shorter (as you would need the 80M ham band.)  So it is very suspicious that you have such a lousy SWR.  All of my Ham 70cm antennas do better than your SWR's on my GMRS radios.  Usually about 1.5 or less.

It's also odd that the radio mfg requires an SWR lower than 1.5:1.   This means less than 4% reflected power which is very small.  Even a 2:1 SWR is only 11% reflected power which is not very much.  What is their problem???

GMRS is limited to 50W and 10% reflected power is not something most engineers would worry about at these power levels.  A 1.5:1 on a portable radio seems ridiculous and unnecessary.... but should be very achievable on a mobile antenna. 

I would check your connectors but also your SWR meter.  Did you test the meter with a dummy load?  Something's not right.

Vince.

[wayoverthere]

3 hours ago, OldRadioGuy said:

It's also odd that the radio mfg requires an SWR lower than 1.5:1.   This means less than 4% reflected power which is very small.  Even a 2:1 SWR is only 11% reflected power which is not very much.  What is their problem???

GMRS is limited to 50W and 10% reflected power is not something most engineers would worry about at these power levels.  A 1.5:1 on a portable radio seems ridiculous and unnecessary.... but should be very achievable on a mobile antenna.

given the number of reports of problems i've come across with the 50x1, i'd hazard a guess it's a combination of not so great components already run close to the limit, less than stellar quality control, and a little bit of covering themselves for warranty claims.

mine has been solid so far, but i haven't subjected it to any particularly long ragchewing.

[mbrun]

given the number of reports of problems i've come across with the 50x1, i'd hazard a guess it's a combination of not so great components already run close to the limit, less than stellar quality control, and a little bit of covering themselves for warranty claims.
mine has been solid so far, but i haven't subjected it to any particularly long ragchewing.

I agree. In addition, a manufacturer with integrity would actually publish a maximum value the radio can safely handle, rather than hiding it in their back pocket and pulling it out when they want to deny a warranty claim. If it is not published they are then in a position to move it at will so as to always suit them. Also, a good design would include a substantial safety margin to ensure the longevity of the product under varied typical conditions.


Michael
WRHS965
KE8PLM

[wayoverthere]

4 hours ago, mbrun said:

Also, a good design would include a substantial safety margin to ensure the longevity of the product under varied typical conditions.

They do actually list the 1.5 swr limit in the manual (twice in the antenna section), but I agree with this take...I don't think they build in much margin.

[mbrun]

They do actually list the 1.5 swr limit in the manual (twice in the antenna section), but I agree with this take...I don't think they build in much margin.

Glad to learn it is in writing in this case.


Michael
WRHS965
KE8PLM