RadioReference on Facebook   RadioReference on Twitter   RadioReference Blog
 

Go Back   The RadioReference.com Forums > Commercial, Professional Radio and Personal Radio > Commercial Radio Antennas


Commercial Radio Antennas - Please keep discussion related to professional, commercially used antennas and antenna systems for the two-way radio industry. Topics for the use of these antennas on amateur bands are accepted here.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #21 (permalink)  
Old 05-30-2017, 6:51 PM
madrabbitt's Avatar
Member
  Amateur Radio Operator
Amateur Radio
 
Join Date: Apr 2004
Location: NM
Posts: 507
Default

Quote:
Originally Posted by mmckenna View Post
...
mmckenna's responses are pretty much "smart thing, smart thing, super knowledgeable thing, vhf phantoms are bad"

I've learned many things from him over the years, so thats totally a great place to start on your search.

Quote:
Originally Posted by lu81fitter View Post
Just another thought.... If you were to contact an object with your 1/4 wave whip antenna that is hanging low enough to distort it and bend it over as to where it needs to be physically straightened out, it may completely destroy a phantom type antenna.
This is an excellent point. I've ripped a UHF phantom off the top of an ambulance in the past. damaged the mount as well as the fiberglass roof. Apparently the "max clearance" label in the cab was wrong. Totally forgot about it until now.
Reply With Quote
Sponsored links
  #22 (permalink)  
Old 05-30-2017, 7:06 PM
Member
   
Join Date: Mar 2014
Location: Marshall County, Illinois
Posts: 118
Default

I agree with madrabbit. mmckenna is a very knowledgeable person here. I have learned from him an well. He is a valuable asset to the RadioReference community!
Reply With Quote
  #23 (permalink)  
Old 05-30-2017, 8:03 PM
Member
   
Join Date: Mar 2002
Location: New Orleans region
Posts: 2,426
Default

As has been said the use of 1/4 wave antennas on an ambulance is about the best choice you can make. the frequently go under overhangs that will tear normal antennas right off the roof.

i have worked with a number of the ambulance vendors in the past. Unfortunately, the walls are not made to be able to run radio remote cable in after they are installed. So you end up having to run them on the inside surface or under the counters where you can. The electrical feed to run the radios off of is just as bad.

Grounds in most ambulances is poor at best.

Getting back to the roof mounted antennas, I would suggest going with the Sti-Co models of their flex 1/4 wave antennas. I have met both the owner and her main design engineer. The flex antenna can be tied in a know and suffer no damage. You may pay more, but don't have to worry about the antenna hitting things like a low over head roof at a hospital or a tree branch.

If you don't like the suggestions people on the group here have provided, then do as you please. But don't come back crying about the antenna you put on the roof and it didn't hold up.
__________________
Jim
Reply With Quote
  #24 (permalink)  
Old 05-30-2017, 8:04 PM
MCore25's Avatar
Member
  Amateur Radio Operator
Amateur Radio
 
Join Date: Jun 2013
Location: Lone Star Republic
Posts: 2,438
Default

Quote:
Originally Posted by lu81fitter View Post
Just another thought.... If you were to contact an object with your 1/4 wave whip antenna that is hanging low enough to distort it and bend it over as to where it needs to be physically straightened out, it may completely destroy a phantom type antenna.

Don't think I've physically found an instance where it's not worth replacing a ~$10 antenna versus straightening a bent antenna.



Sent from my iPhone using Tapatalk
__________________
If a repeater IDs and no one is on frequency to hear it, does it even make a sound? Yes, because KC5MVZ is monitoring you
Reply With Quote
  #25 (permalink)  
Old 05-30-2017, 10:18 PM
RFI-EMI-GUY's Avatar
Member
  Amateur Radio Operator
Amateur Radio
 
Join Date: Dec 2013
Posts: 1,617
Default

Nothing beats those NMO quarter waves. Put some spares in each rig!
__________________
"Have Spectrum Analyzer, - Will travel" "Going Green"
Reply With Quote
Sponsored links
  #26 (permalink)  
Old 05-30-2017, 10:20 PM
RFI-EMI-GUY's Avatar
Member
  Amateur Radio Operator
Amateur Radio
 
Join Date: Dec 2013
Posts: 1,617
Default

Quote:
Originally Posted by MCore25 View Post
Don't think I've physically found an instance where it's not worth replacing a ~$10 antenna versus straightening a bent antenna.



Sent from my iPhone using Tapatalk
You might even want to leave a small bend at the base if its constantly hitting the same overhang!
__________________
"Have Spectrum Analyzer, - Will travel" "Going Green"
Reply With Quote
  #27 (permalink)  
Old 05-30-2017, 10:32 PM
mmckenna's Avatar
Member
   
Join Date: Jul 2005
Location: WTVLCA01DS0
Posts: 7,478
Default

Yeah, cheap, easy to replace, and tilting them back a bit helps. You can also get them with spring bases, but I'm not convinced they are any better as it moves the bend point higher.

The other benefit is that 1/4 wave antennas are very broad banded.
A properly tuned 1/4 wave VHF antenna will safely cover the entire VHF high public safety band, federal band and down to 2 meters with ease. 2:1 SWR or below. While this may not seem important, interoperability channels (both federal and non federal) can be from 151 up to 170MHz. All your radio really should have all of the band specific interoperability channels programmed into them, without exception. Going with a higher gain antenna, like a 5/8th's wave, can run into issues.
UHF quarter waves are even more wide banded, easily covering the UHF band from federal well up towards T-Band.
Reply With Quote
  #28 (permalink)  
Old 06-03-2017, 8:38 AM
Member
   
Join Date: Feb 2008
Posts: 35
Default Ambulance antennas

Quote:
Originally Posted by kc1efx View Post
Good morning everyone!

I'm looking to see if the community can help me with some suggestions on decent NMO VHF and UHF antenna's to install on a new ambulance my department has acquired. We have 4 mounts center line of the box requiring two UHF and two VHF antennas.

Looking for high-quality products that are low profile and/or include a spring base (just like everyone else they tend to grab the door on the way out).

Considering Phantom antennas purely for that reason, however, I'm finding the consensus is they are junk.
Have been dealing with this ambulance problem of losing whips forever. Seems most of the older Fire Stations as well as the hospital emergency room back in areas have little to no clearance with the modular boxes getting bigger. Finally found a product that will stand up and will never have to be replaced.
A company called STI-CO Industries makes undercover applications for various vehicles and undercover cars that want nothing showing. A good example is a number plate frame!! buttt very pricey.
So I buy my parts from Tessco in Maryland, sure many of you have dealt with or heard of them. Stico makes a black quarterwave standard tad/mount Motorola uses. It is field tunable and comes in 136-1000mz. This antenna is made of an amazing material called Nitinol....I call it piano wire. You can litterly take the whip, tie it in a knot, untie it and it comes back to a straight whip! It will lay down flat with next to no clearance and pop back up again. These have proven to be perfect for the application, and cost $37 which is pricey for a quarterwave, but worth not having to check your roof on a daily basis to count how many antennas are left.
Also a good idea when the vehicles being built to favor the vhf antennas up front, seems the rear antennas take the brunt of the beating backing in the ramps at the hospitals. Hope this helps out, I know I for one haven't replaced a single ambulance antenna in a couple years. I do Motorola public safety radios for municipals.....
The exact model for this antenna is ROOF-FT=NITI-M.
Good luck

Last edited by lifeisgoodoneasystreet; 06-03-2017 at 8:41 AM.. Reason: missing model #
Reply With Quote
  #29 (permalink)  
Old 06-04-2017, 5:35 AM
JFDoering's Avatar
Member
  Audio Feed Provider
Audio Feed Provider
 
Join Date: Oct 2003
Location: Dunlap, IL
Posts: 31
Exclamation Fiberglass Roof: Caution!

If your rig has a non-metallic roof, you will need to add a ground plane under the antenna unless you install a "no ground plane" antenna designed for that application. No ground plane antennas, such as the Laird model B1322N for VHF hi-band, will be about three times longer than an 18" quarter-wave.
__________________
J.F. Doering Jr.
Reply With Quote
  #30 (permalink)  
Old 06-04-2017, 2:37 PM
Member
   
Join Date: Feb 2008
Posts: 35
Default

Quote:
Originally Posted by JFDoering View Post
If your rig has a non-metallic roof, you will need to add a ground plane under the antenna unless you install a "no ground plane" antenna designed for that application. No ground plane antennas, such as the Laird model B1322N for VHF hi-band, will be about three times longer than an 18" quarter-wave.
Correct. We ARE assuming the vehicle being new has the proper ground plane inside. Most coach companies that install the mounts per request of the purchaser are using a circular plate the size of the quarter wave. The kits are also available online if it's a do it yourself. On an ambulance with just fiberglass, a no ground plane antenna with a 3/4 tad mount will rip right out of the fiberglass. They also have a rather heavy duty spring which is not very forgiving when hit toward the bottom. Very little on the tabs holding it in there. Either way, a 3/8 style hole mount is better for the application no matter what you're using for an antenna.
The no ground plane antennas you refer to are half wave, so the cut will be about double, not 3 times longer. I just put one on a John Deer tractor, 156mz was about 31 inches. Still too much for the roof of an ambulance. Bottom line is do it right, have the dealer install the proper grounding, then use what you want.
Reply With Quote
  #31 (permalink)  
Old 06-05-2017, 6:29 PM
Member
   
Join Date: Feb 2009
Location: Pittsburgh, Pa.
Posts: 302
Default

best to use 1/4 wave whips

they give great performance and are extremely durable
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 6:23 AM.


Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
All information here is Copyright 2012 by RadioReference.com LLC and Lindsay C. Blanton III.Ad Management by RedTyger
Copyright 2015 by RadioReference.com LLC Privacy Policy  |  Terms and Conditions