Results 1 to 15 of 15

Thread: Multiband antennas...

  1. #1
    Join Date
    Aug 31, 2015
    Posts
    413
    Thanks
    501
    Thanked 438 Times in 185 Posts
    Country: United States

    Default Multiband antennas...

    I am new into this end of the pool... but trying to see if I am just having bad luck.
    I (and several others) want a multiband antenna for our vehicles. I ordered a Browning BR-137 as the guinea pig. VHF was pretty decent (140-160 no more than 1.6:1), but UHF was complete garbage. Tuning the antenna resulting in 1.9:1 at best anywhere in UHF.

    For the first few people, they just want VHF and UHF with some gain and not a mile long antenna - so I am looking at the other Browning, Laird, and Larsen products. The last few, and myself, want 7/800.
    Goal for the bands are: 144-160, 440-470, and 7/800. 100w handling.

    I saw Larsen has a few antennas marketed as 150-174, but not sure if they hold up below 150.


  2. #2
    Join Date
    Sep 04, 2015
    Location
    In the Corn
    Posts
    455
    Thanks
    260
    Thanked 393 Times in 152 Posts
    Country: United States

    Default

    As you probably know a 1/4-wave VHF whip will tune up fine on UHF. Doesn't help you as much for 7/800 but that's an option if needed.

    Typically the antennas I've used that were rated 150+ MHz worked decently well down to 146 at the least. Off the top of my head the low end got up to around 1.7 or 1.8 which in my book at least is acceptable.

  3. #3
    Join Date
    Jun 25, 2013
    Posts
    761
    Thanks
    382
    Thanked 173 Times in 116 Posts
    Country: Belarus

    Default

    Quote Originally Posted by axel View Post
    As you probably know a 1/4-wave VHF whip will tune up fine on UHF.
    Yes, but:

    1. Only in a few MHz range (may be 5-7 MHz only, but non tens);
    2. With no acceptable radiation pattern. As result, antenna doesn't work properly.

    One of our guys used VHF 1/4 antenna as 3/4 UHF antenna, SWR @ UHF was fine (below 1.5), but always have had problems with signal levels (can't access repeater, voice breaks, etc.). All of them are gone when he replaced VHF antenna with true UHF antenna.

    Here is rough radiation pattern model that explains you why 3/4 GP antenna will never not work properly (regardless of SWR value):

    VHF-UHF34.jpg

    Pattern in a vertical plane (right one) is broken in 3 parts, and the main petal is raised at 55 degrees (what is too high for LMR, but maybe not bad for SATCOM, LOL).

    Pattern might vary from car to car, from ground type used (type of metal or radials), antenna base (magnet vs through-hole), etc. But the main idea remains the same - 3/4 GP antenna doesn't have proper radiation pattern. And 'knows' absolutely nothing about antenna radiation pattern / radiation efficiency.
    [I][FONT=times new roman][COLOR=#696969]Everyone who loves RadioReference get into the hell. [U]Especially those[/U] who also love PL-259 connectors.[/COLOR][/FONT][/I]

  4. The Following 4 Users Say Thank You to MotFAN For This Useful Post:

    Alpha (Jan 02, 2019),apx (Jul 06, 2019),axel (Dec 29, 2018),Navy_BOFH (Dec 30, 2018)

  5. #4
    Join Date
    Jul 11, 2012
    Posts
    1,135
    Thanks
    1,078
    Thanked 1,610 Times in 688 Posts
    Country: United States

    Default

    This new offering from Larsen looks promising. A friend has one to evaluate... if they pan out my next mobile install will be four of these run into triplexers.

    NMO150450758-1843-TDS.pdf

  6. The Following 5 Users Say Thank You to motorola_otaku For This Useful Post:

    apx (Apr 27, 2019),com501 (Jan 04, 2019),crazyboy (Jan 04, 2019),Dubs (Jan 04, 2019),PossumCop (Jan 06, 2019)

  7. #5
    Join Date
    Dec 21, 2017
    Posts
    35
    Thanks
    13
    Thanked 22 Times in 14 Posts
    Country: United States

    Default

    Quote Originally Posted by motorola_otaku View Post
    This new offering from Larsen looks promising. A friend has one to evaluate... if they pan out my next mobile install will be four of these run into triplexers.

    NMO150450758-1843-TDS.pdf
    That is a lot more aesthetically pleasing than the PCTEL wide spectrum antenna.

  8. The Following User Says Thank You to Motodan31 For This Useful Post:

    crazyboy (Jan 04, 2019)

  9. #6
    Join Date
    Apr 14, 2015
    Posts
    46
    Thanks
    27
    Thanked 11 Times in 8 Posts
    Country: United States

    Default

    Quote Originally Posted by motorola_otaku View Post
    This new offering from Larsen looks promising. A friend has one to evaluate... if they pan out my next mobile install will be four of these run into triplexers.

    NMO150450758-1843-TDS.pdf
    That 800 elevation cut looks pretty flat. It could be fun to compare to the Laird multiband which seems to have a little higher 800 gain but at higher elevation. I wish I could find a pattern for a 5/8th 800 mhz from Laird too. (-not an rf engineer)

  10. #7
    Join Date
    Mar 25, 2015
    Posts
    246
    Thanks
    257
    Thanked 139 Times in 68 Posts
    Country: United States

    Default

    motorola_otaku that antenna looks super promising! Alot better to look at than the laird or pctel. My only reservation is its performance on the vhf amateur range. 2.5+ in a very narrow range is rough. Commercially speaking though I will surely be buying one.
    I'm here to learn!

  11. #8
    Join Date
    Aug 31, 2015
    Posts
    413
    Thanks
    501
    Thanked 438 Times in 185 Posts
    Country: United States

    Default

    Quote Originally Posted by motorola_otaku View Post
    This new offering from Larsen looks promising. A friend has one to evaluate... if they pan out my next mobile install will be four of these run into triplexers.

    NMO150450758-1843-TDS.pdf
    That is the one I am keeping my eye out for as well... but I wonder what it looks like under 150MHz. I would hate to run a second antenna just for my occasional ham ramblings.

    I have looked at the PCTEL, and it looks like the Browning BR-136 is a re-label of the same antenna. At least with that (fugly) antenna, I know I will get the bandwidth.

  12. #9
    Join Date
    Jan 23, 2014
    Posts
    219
    Thanks
    2
    Thanked 74 Times in 53 Posts

    Default

    I am installing these for all of our Harris XG-100 mobiles. So far we have had very good luck over the last couple years
    https://www.tessco.com/product/368700

    Sent from my SM-G950U using Tapatalk

  13. #10
    Join Date
    Jan 23, 2014
    Posts
    68
    Thanks
    13
    Thanked 31 Times in 16 Posts
    Country: United States

    Default

    Quote Originally Posted by motorola_otaku View Post
    This new offering from Larsen looks promising. A friend has one to evaluate... if they pan out my next mobile install will be four of these run into triplexers.

    NMO150450758-1843-TDS.pdf
    I dont have privs yet to get to this. Can you post a URL?

  14. #11
    Join Date
    Jul 14, 2013
    Posts
    182
    Thanks
    294
    Thanked 237 Times in 109 Posts

    Default

    Quote Originally Posted by SoloCDR View Post
    I dont have privs yet to get to this. Can you post a URL?
    Not trying to be a smartass, but the part number is the first part of the name of the file. You should be able to google Larsen NMO150450758 data sheet, although it does say Confidential and proprietary so maybe not?

  15. #12
    Join Date
    Oct 09, 2012
    Posts
    267
    Thanks
    178
    Thanked 88 Times in 47 Posts

    Default

    Not to beat a dead horse but... I am looking for an NMO mobile antenna solution now as well. Installing an XG-100M an I would like to cut down on the number of antennas I have.

    I am of course looking at the Larsen NMO150/450/758 and the Sti-Co RFMT-TB-V/U/C. I do need TX/RX down to 139 though. Anyone using either of these down that low?

    I could have sworn that I had seen an NMO antenna similar to the Sti-Co but without all the plastic parts on it.. much lower profile. I can't for the life of me find it anymore though.

  16. #13
    Join Date
    Jan 23, 2014
    Posts
    219
    Thanks
    2
    Thanked 74 Times in 53 Posts

    Default

    What model StiCo are you looking at? We have a few of the Harris sold StiCo RFMT-TB-V/U/C NMO antennas in the field with good results. We also have the Laird multi-band and Panorama Sharkee antennas in service on XG-100m units.

    Out of about 20 Sharkee antennas I believe we have had one develop an issue. No issues reported with either of the other two. Granted that all of them spend 99% of the time within the footprint of our system that is designed for 14dB-20dB in-building coverage.

    Sent from my SM-G950U using Tapatalk

  17. #14
    Join Date
    Oct 09, 2012
    Posts
    267
    Thanks
    178
    Thanked 88 Times in 47 Posts

    Default

    I'm looking at the same model Sti-Co you are using. The performance on it didn't look so hot though and I am concerned about it breaking or tearing out of the roof. My use area is primarily the mountains of VA/WV so I hit alot of trees. I am currently using a pair of Comtelco A1511B's (spring 1/4 waves).

  18. #15
    Join Date
    Jan 23, 2014
    Posts
    219
    Thanks
    2
    Thanked 74 Times in 53 Posts

    Default

    Based on the ones we have in service, I wouldn't be too worried about it tearing out the roof but I can see breakage of the mast(s) being a concern although we havent broken any yet. I can certainly see performance being compromised on any of these unit though compared to standard band specific radiators.

    One option (if performance is your main concern) is a tri-plexer. We had a department head that parked his Tahoe in the garage at home and only had about 6" clearance from the roof. We installed a VHF/UHF/7-800 tri-plexer on his 100m that I believe was from Panorama to use three band specific phantom antennas. It swept ok on all bands with an Anritsu.

    Sent from my SM-G950U using Tapatalk