Ground Plane Antenna Performance 1/4 (6") v. 5/8 (15") v 1/2 (31") wave - JEEP

[Extreme]

Will I gain any performance (distance and/or clarity) with one of the base loaded  antennas over a 6" 1/4 wave?  Both would be on the same 8" square ground plane on my Jeep.  Wondering if the added height above the roof will be of much benefit.  The 1/4 is working fine, just nit-picking.  Spring loaded base would be a must if I go taller.  The ground plane would remain the same.

Assuming all will screw onto the existing NMO mount.

If they need tuning, I'll likely opt out.  Guess I could experiment and be careful to swap to the shorty in the overhead brush.

UHF High Gain Antennas: Laird TE Connectivity B4503S (theantennafarm.com)   

5/8 wave is 15"

UHF High Gain Antennas: Laird TE Connectivity B4505CS (theantennafarm.com)

1/2 wave is 31"

UHF Quarter Wave Antennas : Laird TE Connectivity AB450 (theantennafarm.com)

1/4 wave is 6"

[BoxCar]

The 4503 offers the most gain. Liard antennas normally don't need tuning.

[marcspaz]

The best antenna for you is going to vary a bit, depending on where you are going to be using the radio and what you want to accomplish.

 

On a vehicle, a 5/8 wave antenna is going to show at least 3dB gain over a 1/4 wave, and at least 1dB of actual gain (depending on design, it can be much higher).  This antenna has the least amount of elevation tolerance.  So, if you live in a hilly/mountainous area, this may not be the best option, but it would be good in large geographically flat areas.

 

A 1/2 wave doesn't require a ground plane and has about 2.1 dB of gain over a 1/4 wave, but it has no actual gain... its straight break-even.  It also has a bit more tolerance to elevation.

 

A 1/4 wave actually has a loss of about 2/10ths of a dB.  While it doesn't provide as much range, in hilly or mountainous areas, its going to be the best choice due to the very high elevation tolerance. 

 

Based on this, I actually carry a 5/8 wave antenna that is about 32" tall and about 6dB gain, and a 1/4 wave antenna.  Then I just swap them on and off the vehicle depending on the terrain I am in and the range needed.

[Extreme]

5 hours ago, marcspaz said:

The best antenna for you is going to vary a bit, depending on where you are going to be using the radio and what you want to accomplish.

 

On a vehicle, a 5/8 wave antenna is going to show at least 3dB gain over a 1/4 wave, and at least 1dB of actual gain (depending on design, it can be much higher).  This antenna has the least amount of elevation tolerance.  So, if you live in a hilly/mountainous area, this may not be the best option, but it would be good in large geographically flat areas.

 

A 1/2 wave doesn't require a ground plane and has about 2.1 dB of gain over a 1/4 wave, but it has no actual gain... its straight break-even.  It also has a bit more tolerance to elevation.

 

A 1/4 wave actually has a loss of about 2/10ths of a dB.  While it doesn't provide as much range, in hilly or mountainous areas, its going to be the best choice due to the very high elevation tolerance. 

 

Based on this, I actually carry a 5/8 wave antenna that is about 32" tall and about 6dB gain, and a 1/4 wave antenna.  Then I just swap them on and off the vehicle depending on the terrain I am in and the range needed.

Thanks Marc.  As soon as I read this I realized I'd been taught this here a few years ago when pondering antennas... sheesh.

My 1/4 is great in the mountains but we do have some extremely long shots with potential for more reach.  I've hit a repeater from 50 miles so don't know what better I could ask.   I might consider a 5/8 to play with.

[WRFP399]

I found zero difference  between a 1/4 wave and a 5/8 over 5/8 collinear antenna where I am when talking to a repeater. We have mountains as well as wide open flat area. I go with a 1/4 wave because there is no reason to have a larger antenna if it doesn't do anything better.

[Extreme]

20 minutes ago, WRFP399 said:

I found zero difference  between a 1/4 wave and a 5/8 over 5/8 collinear antenna where I am when talking to a repeater. We have mountains as well as wide open flat area. I go with a 1/4 wave because there is no reason to have a larger antenna if it doesn't do anything better.

Agreed.  I've been trying to say just this to my off-road buddies who're getting their first mobiles.  A lot of them are in Jeeps with fiberglass tops so that's an issue and they're leaning toward longer antennas to get them above the top.  I was lucky enough to have a perfect spot for an 8 x 8" ground plane for my 1/4 high at the rear of the LJ.

It is cool that they're getting away from CB and into GMRS.  Better in every way on the trail or hunting in my experience.

Guess I could take this to the Jeeps & Radios thread.

Thanks for the feedback and reminding me of radio 101.

 

[Lscott]

20 minutes ago, Extreme said:

Agreed.  I've been trying to say just this to my off-road buddies who're getting their first mobiles.  A lot of them are in Jeeps with fiberglass tops so that's an issue and they're leaning toward longer antennas to get them above the top.  I was lucky enough to have a perfect spot for an 8 x 8" ground plane for my 1/4 high at the rear of the LJ.

It is cool that they're getting away from CB and into GMRS.  Better in every way on the trail or hunting in my experience.

Guess I could take this to the Jeeps & Radios thread.

Thanks for the feedback and reminding me of radio 101.

 

For fiber glass tops a good choice is a 1/2 wave antenna. They typically don't really need a ground plane so you have much more flexibility in mounting locations. 

[gortex2]

• As said depends on use. I run a 1/4 wave on the JK on the front fender. Was at JJUSA this weekend. Both days everyone on my trip that had a mobile had the Phantom antenna. We had no issues on our trails. Half the group had handhelds and I could here everyone on my trail with no issues. 
•  

[marcspaz]

9 minutes ago, gortex2 said:

• As said depends on use. I run a 1/4 wave on the JK on the front fender. Was at JJUSA this weekend. Both days everyone on my trip that had a mobile had the Phantom antenna. We had no issues on our trails. Half the group had handhelds and I could here everyone on my trail with no issues. 
•  

 

^^^ This is a great example of "it depends".

 

6 hours ago, WRFP399 said:

I found zero difference  between a 1/4 wave and a 5/8 over 5/8 collinear antenna where I am when talking to a repeater. We have mountains as well as wide open flat area. I go with a 1/4 wave because there is no reason to have a larger antenna if it doesn't do anything better.

 

5 hours ago, Extreme said:

Agreed.  I've been trying to say just this to my off-road buddies who're getting their first mobiles.  A lot of them are in Jeeps with fiberglass tops so that's an issue and they're leaning toward longer antennas to get them above the top.  I was lucky enough to have a perfect spot for an 8 x 8" ground plane for my 1/4 high at the rear of the LJ.

It is cool that they're getting away from CB and into GMRS.  Better in every way on the trail or hunting in my experience.

Guess I could take this to the Jeeps & Radios thread.

Thanks for the feedback and reminding me of radio 101.

 

 

 

I understand you are discussing personal experience... but there is most definitely a performance difference between a 1/4 wave and a 5/8 wave, even on a repeater.

 

This is not a scientific test, by any means.  I know my radio does not have a truly calibrated S-Unit meter. This is solely an exercise in observed differences with my personal gear.

 

 

[WRQZ361]

     There is no substitute for effective radiating and receiving surface area in an antenna system (within reasonable limits). Like camera lenses, larger antennas inherently gather and disperse RF better than less substantial ones. Both undoubtedly "work", but where does your cost/benefit line lie on a mobile antenna? Are you wringing every ounce out, or are you happy with what ya got? Those giant radio-telescopes are proof of this, albeit in the extreme. Ideally, we'd all be getting base-antenna performance out of an inconspicuous 6-inch magnet-mount whip, but that's not the case, and never will be. Properly applied, and all other things equal, of course...    

[wayoverthere]

2 hours ago, WRQZ361 said:

     There is no substitute for effective radiating and receiving surface area in an antenna system (within reasonable limits). Like camera lenses, larger antennas inherently gather and disperse RF better than less substantial ones. Both undoubtedly "work", but where does your cost/benefit line lie on a mobile antenna? Are you wringing every ounce out, or are you happy with what ya got? Those giant radio-telescopes are proof of this, albeit in the extreme. Ideally, we'd all be getting base-antenna performance out of an inconspicuous 6-inch magnet-mount whip, but that's not the case, and never will be. Properly applied, and all other things equal, of course...    

Not to mention some have varying height considerations to worry about....one more of those "compromise" aspects.

That double 5/8 works nicely on the roof of the truck, but doesn't get along well with the parking garage at work. Likewise with the ca2x4sr that's also up there....do i want to bounce it off of every beam through 5 (or more) floors of parking garage? Stop and fold it before I pull in? Or accept that a 1/2 wave base loaded whip and a comet sbb1 work well well enough for 90% of my usage and are short enough not to usually be a clearance issue, and just swap on the bigger whips when I won't be in that parking garage for a bit (mostly this).

[KAF6045]

4 hours ago, WRQZ361 said:

Those giant radio-telescopes are proof of this, albeit in the extreme.

These days, most of the big radio-telescopes are really phased arrays of smaller radio telescopes using long baseline distances to produce resolution that a single larger dish is incapable of (Especially since I think Arecibo is (still) out-of-action.

[Lscott]

On 9/26/2022 at 12:24 AM, KAF6045 said:

These days, most of the big radio-telescopes are really phased arrays of smaller radio telescopes using long baseline distances to produce resolution that a single larger dish is incapable of (Especially since I think Arecibo is (still) out-of-action.

https://www.naic.edu/ao/repairs-update

[WRQG411]

I have this antenna, specs don't tell me if it's 1/2 or 5/8 wave and if it requires a ground plane or not.  It's the one I run when I'm not going in and out of my garage at home.  It screws on to a Midland lip mount NMO that's installed on the corner of the hood just in front of the driver's side A pillar.  When I am running back and forth to work and using my garage, I replace it with a Midland "phantom" that they claim has 3db gain.  I've been able to hit a repeater 60 miles away with the Laid over some fairly flat with a few hills between terrain.  I have a MXT575 running straight from the battery through a Kenwood choke.

 

https://theantennafarm.com/shop-by-categories/shop-all/mobile-antennas/300-512-mhz-uhf/high-gain-antennas/6538-laird-connectivity-bb4505cr-detail

[BoxCar]

Laird BB-4505cr

Manufacturer

TE Connectivity

Info

Ground Plane Required 

Frequency (MHz)

450 - 470 MHz

Product Narrative 

TE Connectivity ongoing commitment to refinement in mechanical and electrical design has resulted in the release of their latest product, the mobile coil antenna with an elastomer spring. The new elastomer spring provides increased flexibility, better shape retention, and eliminates electronic noise & road noise compared to stainless steel springs. The mobile coil antennas will continue to maintain all of the features that make them unique, such as stainless steel whips, housings constructed with ABS material injection molded around a solid brass insert, and gold plated push pin contacts. Together, the mobile coil antenna and elastomer spring, make TE Connectivity the obvious choice for quality and long lasting value for demanding mobile radio communications.     

Gain (dBi)

5 db

Maximum Power (Watts)

200

Whip Length (In.)

34"

Whip Material

Stainless steel  

Bandwidth

20  MHz

Spring Incl. 

Yes

Color

Black Base w/ Black Whip  

Mount Type

Order NMO Type Mount Separately

[wayoverthere]

1 hour ago, WRQG411 said:

I have this antenna, specs don't tell me if it's 1/2 or 5/8 wave and if it requires a ground plane or not.  It's the one I run when I'm not going in and out of my garage at home.  It screws on to a Midland lip mount NMO that's installed on the corner of the hood just in front of the driver's side A pillar.  When I am running back and forth to work and using my garage, I replace it with a Midland "phantom" that they claim has 3db gain.  I've been able to hit a repeater 60 miles away with the Laid over some fairly flat with a few hills between terrain.  I have a MXT575 running straight from the battery through a Kenwood choke.

 

https://theantennafarm.com/shop-by-categories/shop-all/mobile-antennas/300-512-mhz-uhf/high-gain-antennas/6538-laird-connectivity-bb4505cr-detail

did some additional searching, but of the few sites i checked, none of them mentioned the 'wave' on that one..that said, half educated guess given the size, and the coil in the middle, that it'd likely be a 5/8 over 5/8 wave.

i've had good results with a similar 5/8 over 5/8 browning.

[WRQG411]

Based on it's design, that's what I was leaning to as well, 5/8 over 5/8.  Not sure how I missed the ground plane in the antenna farm specs, guess is was looking for GP or NGP.  My oversight.  Thanks for the assist!