Best Lowband Mobile Antenna?

[902]

https://www.theantennafarm.com/catalog/laird-tech-wpc39s0b-001-6438.html any more reviews on this antenna?

Wow, that's an expensive mobile antenna, as antenna prices go. I read your bandspread and it should be okay (maybe ask them for advice on pruning the antenna to move resonance up a bit). If you're willing to spend that, it should be fine for you.

Personally, I've never had a mobile antenna work better than a ball-and-spring for low band. The other antennas work, but that ball-and-spring beats them for performance.

 

[kb3isq]

If you want to use an NMO mount you will want a base loaded antenna, MAXRAD are on E-bay for around $50-60. If you want to use a full 1/4 wave (as do most rural Police and Emergency services then you should get a three bolt mount with a whip cut to the closest freq. you want IE: 1/4 wave antenna is length in inches (L) = 2808 Divided by Frequency (Mhz)
39.5 Mhz = 71.0 inches, 46.0 Mhz = 61.04 inches etc

 

[reconrider8]

i just mainly want better mobile pickup for NCHP and i read up on the larsen and laird and what not lol to confusing

 

[kb3isq]

What do they use? most likely base loaded or 1/4

 

[russellmaher]

The Laird antenna you're looking at is $120.00 plus shipping.

Take a look at the stainless steel whip and the ball & spring mount that most State Police and Highway Patrol units use, and it will cost less.

CB Ham Radio HD Ball Swivel Antenna Mount Spring 102" | eBay

New 102 inch CB Ham Radio Antenna Stain Steel Whip | eBay

Russell

 

[reconrider8]

I saw something like that but Idk where I can mount it on my car

 

[russellmaher]

1. The center of the trunk (if your car has a trunk). Just what type of car do you have?

2. The side of the rear quarter panel (that's the spot where the MA State Police mount theirs).

 

[reconrider8]

I was looking at something that would fit on a trunk lip nmo mount

 

[russellmaher]

Oh, in that case I wouldn't try a 102 inch whip on a trunk lip mount. Too much pressure on such a small mount would be unsafe.

I do have an Austin Spectra with a trunk lip mount on my Malibu....but it's only 33 inches high.

I would go with the 102 inch with the spring mount if I wanted good reception of Low Band comms, but a smaller antenna would be best for your mounting situation.

Russell

 

[reconrider8]

yea i have a spectra as of now but i was trying to go better with like a larsen nmo40 or that laird that i was looking at... something with nmo mounts so i can use what i have already

 

[russellmaher]

Are you using the Spectra to monitor low band? Did you trim the top section to improve the low band reception? How did it work after you trimmed it?

I'm asking because I haven't cut mine at all, but don't listen to low band, so it doesn't matter.

Russell

 

[reconrider8]

Na I've never touched the top infact I've never touched it more then installing it

 

[reconrider8]

just received my nmo-40 and have it on my car and with the quick test i did i was still getting static channels that just sat there on 1/2 squelch. what do you guys do about those?

 

[902]

just received my nmo-40 and have it on my car and with the quick test i did i was still getting static channels that just sat there on 1/2 squelch. what do you guys do about those?

What kind of static is it? Is this a low-level signal that's always there, no matter what you do? Is it static artifact superimposed on stuff you're receiving? Is it static that's only there when the car is running, or when someone else passes you? Is it static that goes away when you turn the ignition off?

Each of those is a different thing.

The first one, a low level signal, might be birdies in the scanner.

The rest could be something being coupled in from your (or another vehicle's) spark ignition system, or automobile electronics/microprocessor-driven stuff. Or it could be from other sources, like something in the neighborhood.

 

[reconrider8]

car was off and it was mainly on the 30 bAnd once it got to 40 it went away. i was thinking maybe birdies but i didnt wanna lock out something that i may hear some traffic on

 

[Anderegg]

Stupid question, but for RX ONLY, does trimming or exact length for receive frequency matter much? I run an NMO L bracket on the side of a Prius with a base loaded 40MHz whip, simply to keep it low enough to not clip things like low flying aircraft. Strangely enough, the antenna receives better with the side of the car the antenna is on being non the opposite side of the signal.

Anyway, for 40MHz RX ONLY, do you think I would get better general reception if I put a 27MHz whip so that it cleared the car a bit more and was up in the clear air a little more?

Paul

 

[prcguy]

If the antenna resonates very far from where you need it then tuning can make a huge improvement. For example, a stock Austin Spectra resonates around 33MHz and is about 17dB down in performance at 43MHz if not cut for that frequency. Trim it for 43Mhz and you get your 17dB back but loose 33MHz and so on.

Compared to a tuned antenna at 40MHz, a CB antenna will be at least 10dB and probably closer to 20dB worse. I've tested some VHF low antennas on an antenna range and they are narrow band and don't work very well outside where they are tuned.
prcguy

Stupid question, but for RX ONLY, does trimming or exact length for receive frequency matter much? I run an NMO L bracket on the side of a Prius with a base loaded 40MHz whip, simply to keep it low enough to not clip things like low flying aircraft. Strangely enough, the antenna receives better with the side of the car the antenna is on being non the opposite side of the signal.

Anyway, for 40MHz RX ONLY, do you think I would get better general reception if I put a 27MHz whip so that it cleared the car a bit more and was up in the clear air a little more?

Paul

 

[Anderegg]

Do receiving antennas resonate? Also, if I need to RX on low band and VHF hi, which would work best feeding both radios, a low band or VHF high whip? I am not sure how the coils work on those 49" whips.

Paul

 

[prcguy]

For the type of antennas you are discussing, yes they are resonant and work best where they are tuned and can really degrade when you get too far from the sweet spot.

Then you can have undesirable radiation patterns where the antenna may be resonant and have a good match but it points up in the sky and is lousy at the horizon where you need it. An example of this might be a 9ft CB whip used on VHF or UHF where it might actually match but since its several wavelengths long it has lobes that point all over the place but probably not where you want.

A single band VHF lo or VHF hi antenna will not work on both bands, or I should say they will be so severely degraded on one band that its not worth considering in my opinion. An antenna designed for both VHF lo and VHF hi should not only provide a good match at the frequencies you want but also have a useful pattern at the horizon. The Austin Spectra is one of the few currently made antennas that fit that description but its fairly narrow band on VHF lo at maybe 1MHz of good useful band width before it starts to degrade.

If you want the full 30 to 50MHz range with good performance then you have to consider a very large broad band military surplus antenna. I've measured those at between 8 to 20dB better in the 30 to 50MHz range than an Austin Spectra measured on the same vehicle but they are 9ft long, thick, heavy and green.
prcguy

Do receiving antennas resonate? Also, if I need to RX on low band and VHF hi, which would work best feeding both radios, a low band or VHF high whip? I am not sure how the coils work on those 49" whips.

Paul

 

[motorola_otaku]

https://www.theantennafarm.com/catalog/laird-tech-wpc39s0b-001-6438.html any more reviews on this antenna?

This antenna was a SP product for the California Highway Patrol, to meet their requirements for sustained TX power handling and wind load. I own one and it works as advertised. DO NOT TRIM THE WHIP. It uses a LC network in the base to achieve the wide operating bandwidth, and trimming the whip will make it resonant nowhere.

If y'all are serious about mobile low band monitoring you need to get away from using scanners and get a commercial radio. I used a Motorola Syntor X9000 with a Larsen NMO50 cut for 6 meters (the above antenna didn't exist at the time) and had no problem monitoring highway patrol base and mobile traffic in Mississippi, Tennessee, and Maryland. Motorola Maxtracs, Maratracs, Kenwood TK-630s, and 690s are all cheap and plentiful on Ebay but don't have the 29-54 MHz operating range of the Syntor 9K.