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Do I need a ground plane?


8nannyfoe
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So I have a simple Midland MXt 105 as my base station radio.  It has a 5 amp DC power supply.  Just a simple 5 watt jobby.   Anyway, I ran a stock motorola 6 meter cable with 90 degree NMO adapter and a Midland 6db stock antenna.   I had the antenna sitting on top of a 5' fan.  (extremely basic setup)  I was able to talk about 2.8 miles and received a repeater beacon that was 90 miles away running this simple setup. 

 

I decided to drop a significant amount of cash on the set up (my experiment) because it eventually will be at my cabin in the mountains.   I purchased 40' of LMR400 with Times connectors.  (UHF and type N)   I also purchased a  

Laird Technologies FG4605  antenna (also type N)  5db gain.   I temp mounted this antenna in the center of a round patio table (glass top that has a hole for an umbrella)   The frame of the table is aluminum, but none of the cable or antenna is anywhere near the aluminum. 

So I expected to see a significant improvement over my old antenna, however, I think I may have wasted my money.   It performs quite comparable to the stock Midland setup.  Maybe a couple hundred yards further talk. 

 

My question is....will my performance improve with a ground plane on this new antenna setup?

 

 

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This Laird antenna does not need ground plane. Do I read correctly that it is now mounted at the height of 30 inches from the ground? Mount it high on a mast, the higher the better. 10-20-30', and do experiment again.

Yes, lol....you are correct.    So the old Midland antenna was also mounted in the same spot/height as well.   They basically performed equal with a slight edge to the Laird.  (couple hundred yards talk advantage)  On this basis,  if I raised them both equally, am I to assume they will perform equally (basically)  or does the curve of improvement lean more favorably to the Laird as the height increases?   Honestly, if they perform equal at the low height I'm suspecting they will perform equal on top of a mast?  I actually would prefer the tiny profile of the Midland.   The Midland did not have a ground plane either BTW in my test of the Midland 6db gain antenna.

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If you are saying that the stock antenna that came with the MX105 is a 6dBi antenna, I believe that to be in error. At best, it may be 2dBi. The short little midland antenna does need a ground plan, where as some others can benefit from one, but do not need them to achieve acceptable performance.

 

Midland does make a 6dBi version. I own one and find that it does quite well. Even mounted on top of a metal trashcan lid. I believe the Laird antenna you reference is similar.

 

Height is King in GMRS. Get the antenna well above the tree line and you could find yourself achieving simplex distances of 20-50 miles and more. As the antenna elevation drops so too will your usable range. With an elevation of 4-6 off the ground your usable simplex distance could be down to 1/2 - 2 miles or so depending upon the obstacles between the transmitting and receiving antennas.

 

I recently did some testing with a local ham and GMRS’r. I had a high-gain antenna at 56’ (still below tree tops) and could not communicate 8 miles to another location were we testing. Only thing significant between the two antennas was loads and loads of trees (no hills or tall buildings). Using same antenna, radio and power (5 watts) we reached a good 50 miles going a different direction where fewer trees and other obstacles existed between the antennas.

 

Never under estimate the importance of height when it comes to GMRS distance.

 

 

Michael

WRHS965

KE8PLM

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If you are saying that the stock antenna that came with the MX105 is a 6dBi antenna, I believe that to be in error. At best, it may be 2dBi. The short little midland antenna does need a ground plan, where as some others can benefit from one, but do not need them to achieve acceptable performance.

 

Midland does make a 6dBi version. I own one and find that it does quite well. Even mounted on top of a metal trashcan lid. I believe the Laird antenna you reference is similar.

 

Height is King in GMRS. Get the antenna well above the tree line and you could find yourself achieving simplex distances of 20-50 miles and more. As the antenna elevation drops so too will your usable range. With an elevation of 4-6 off the ground your usable simplex distance could be down to 1/2 - 2 miles or so depending upon the obstacles between the transmitting and receiving antennas.

 

I recently did some testing with a local ham and GMRS’r. I had a high-gain antenna at 56’ (still below tree tops) and could not communicate 8 miles to another location were we testing. Only thing significant between the two antennas was loads and loads of trees (no hills or tall buildings). Using same antenna, radio and power (5 watts) we reached a good 50 miles going a different direction where fewer trees and other obstacles existed between the antennas.

 

Never under estimate the importance of height when it comes to GMRS distance.

 

 

Michael

WRHS965

KE8PLM

Yes, I was referring to Midlands GMRS 6db antenna and not the tiny magnet one that came with the MTX105.   I chucked that immediately LOL.   So let me ask you this since you had both.   Do you think raising the Midland antenna up equally as high as I would raise the Laird (35' peek of roofline), they would perform comparably as they performed at ground level?   Or would the Laird somehow begin outperforming the Midland antenna for some reason?   Techy question I suppose, but it would be great to know because I would prefer the Midland, as its appearance is not as bold. 

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Yes, I was referring to Midlands GMRS 6db antenna and not the tiny magnet one that came with the MTX105. I chucked that immediately LOL. So let me ask you this since you had both. Do you think raising the Midland antenna up equally as high as I would raise the Laird (35' peek of roofline), they would perform comparably as they performed at ground level? Or would the Laird somehow begin outperforming the Midland antenna for some reason? Techy question I suppose, but it would be great to know because I would prefer the Midland, as its appearance is not as bold.

Good Morning.

 

Honestly, I do not believe you would able to tell the difference in range between the two models, assuming both are properly installed and working correctly and both are mounted at the same elevation.

 

Something you should know is that VHF and UHF frequencies are what are called ‘line of sight’ frequencies. This means that if two antennas operating on these frequencies can see one another, odds are great the radios connected to them can communicate with one another, even with minimum power. But in reality every tree, plant, tower, building, pole, hill or hump you put between the two antennas reduces effective range.

 

To determine your theoretical best case scenario you start by calculating the radio horizon distance for the two radios that you wish to communicate with one another. Below are some links for you to play with. These calculators assume the earth is a perfectly smooth sphere. As you will see, the higher the Tx and Rx antennas are, the greater the theoretical distance. For two antennas located at 6’ each, the maximum theoretical distance is a mere 6 miles. For the case where one antenna is 35’ and the other is 6’, the maximum theoretical is 11 miles. Both antennas at 35’ and the maximum increases to 16 miles. But since the earth is not smooth (has hills and valleys) and has natural and man-made obstacles (trees and buildings) range is nearly always dramatically reduced. In far fewer cases it goes way up (consider radios on two different mountain tops).

 

You may ask what is the radio horizon. The radio horizon is the point at which (in any horizontal direction) the radio wave is blocked by the surface of the earth. It is nearly the same as your eyes. Go out on a boat on smooth ocean waters. If your eyes are at 6’ above the water, the horizon you see is only a mere 3 miles away. The higher you are above the earth surface, the further away the horizon is that you see. It is the presence of this blocking horizon that prevents the signal from traveling further around the earth.

 

https://www.qsl.net/w4sat/horizon.htm

 

https://www.everythingrf.com/rf-calculators/line-of-sight-calculator

 

https://www.southwestantennas.com/calculator/line-of-sight

 

Hope this helps.

 

 

Michael

WRHS965

KE8PLM

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You had a 6db antenna with 16' of cable then went to a 40' of LMR400. You will have loss in the cable. Granted wont be a ton but will be different than 16' of cable. 

 

As reference I run the Laird antenna on my Motorhome for my repeater and have used it alot. Its a solid antenna. Get it in the air and it will do fine.

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Good Morning.

 

Honestly, I do not believe you would able to tell the difference in range between the two models, assuming both are properly installed and working correctly and both are mounted at the same elevation.

 

Something you should know is that VHF and UHF frequencies are what are called ‘line of sight’ frequencies. This means that if two antennas operating on these frequencies can see one another, odds are great the radios connected to them can communicate with one another, even with minimum power. But in reality every tree, plant, tower, building, pole, hill or hump you put between the two antennas reduces effective range.

 

To determine your theoretical best case scenario you start by calculating the radio horizon distance for the two radios that you wish to communicate with one another. Below are some links for you to play with. These calculators assume the earth is a perfectly smooth sphere. As you will see, the higher the Tx and Rx antennas are, the greater the theoretical distance. For two antennas located at 6’ each, the maximum theoretical distance is a mere 6 miles. For the case where one antenna is 35’ and the other is 6’, the maximum theoretical is 11 miles. Both antennas at 35’ and the maximum increases to 16 miles. But since the earth is not smooth (has hills and valleys) and has natural and man-made obstacles (trees and buildings) range is nearly always dramatically reduced. In far fewer cases it goes way up (consider radios on two different mountain tops).

 

You may ask what is the radio horizon. The radio horizon is the point at which (in any horizontal direction) the radio wave is blocked by the surface of the earth. It is nearly the same as your eyes. Go out on a boat on smooth ocean waters. If your eyes are at 6’ above the water, the horizon you see is only a mere 3 miles away. The higher you are above the earth surface, the further away the horizon is that you see. It is the presence of this blocking horizon that prevents the signal from traveling further around the earth.

 

https://www.qsl.net/w4sat/horizon.htm

 

https://www.everythingrf.com/rf-calculators/line-of-sight-calculator

 

https://www.southwestantennas.com/calculator/line-of-sight

 

Hope this helps.

 

 

Michael

WRHS965

KE8PLM

Thank you for this!   Very informative!   You just made this forum great!!

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