Somehow I doubt this antenna is worth the price... what do you think?

[Omega-TI]

It seems to me that even with the ground plane type base, this wouldn't an order of magnitude better than a standard rod antenna or a cheap dipole? Of course for those with HOA's, one could set it on their patio and tell the board to take a flying leap. Still, for $65.73 at Amazon I question. What say you, am I off-base here?

 

[KevinC]

Trying my best, but what does this have to do with SDR?

 

[Omega-TI]

Trying my best, but what does this have to do with SDR?

Oh, it's "advertised" in the title of the link for SDR's. Yeah, a radio is a radio is a radio, but I had to put this someplace.

 

[GTR8000]

but I had to put this someplace.

Well, I don't think you necessarily "had" to put it anywhere, but if you felt compelled, was the Antennas and Associated Hardware forum closed at the time you posted this thread?

 

[Omega-TI]

I suppose an admin or moderator could have simply moved the thread too, it's not like they've never done it in the past.

 

[paulears]

It won't be better than a dipole - but it could be the same as a dipole - if - you figure out how to tune it to the frequency you want. ¼ waves work pretty much like dipoles, but this does have fairly small ground-lane elements, which might reduce performance a bit.

 

[KevinC]

Well, I don't think you necessarily "had" to put it anywhere, but if you felt compelled, was the Antennas and Associated Hardware forum closed at the time you posted this thread?

It's possible it was closed. We sometimes do that to clean the background, change the bulbs that light up the forum and other general housekeeping chores. We try to do it at not so busy times.

 

[a727469]

Back on topic, as we all know there are multiple how to build articles for similar simple ground planes for usually under $10 …would just have to modify a bit for a telescopic. As far as forum sdr, yes it would work with an sdr!!!😀

 

[PDXh0b0]

I can see people using this for sdr. If it was 4.99 I'd might buy it for the hub, add telescopic radials, or tune it for a specific range.

 

[bharvey2]

I have a couple of NMO mount/adapters with integrated ground radials. Coupled with an NMO VHF/UHF antenna, I have a temporary base antenna or extra mobile antenna.

 

[prcguy]

The ground radials are not tunable so the antenna will only work as a 1/4 wave ground plane at one frequency where the ground radials are factory tuned. A tuned ground plane works a little worse than a 1/2 wave dipole. Any where other than where the ground radials are tuned it will work much worse than a 1/4 wave ground plane.

 

[K4EET]

The ground radials are not tunable so the antenna will only work as a 1/4 wave ground plane at one frequency where the ground radials are factory tuned. A tuned ground plane works a little worse than a 1/2 wave dipole. Any where other than where the ground radials are tuned it will work much worse than a 1/4 wave ground plane.

DISCLAIMER: My brain does not function well due to my Encephalopathy caused by MELAS so this may or may not be correct.

According to the drawing in Post #1, the two closest radials form a triangle. The angles should be 120, 30, and 30 degrees (I think). The radials are the same length and the third side is 19 inches. Throwing those numbers into the triangle calculator at:

Calculator.net: Free Online Calculators - Math, Fitness, Finance, Science

Online calculator for quick calculations, along with a large collection of calculators on math, finance, fitness, and more, each with in-depth information.

calculator.net

The radials should be 10.96966 inches each.





Knowing that, the radials should be tuned (theoretically) to 255.9894 MHz.

Am I correct with all of that? TIA!

 

[PDXh0b0]

DISCLAIMER: My brain does not function well due to my Encephalopathy caused by MELAS so this may or may not be correct.

According to the drawing in Post #1, the two closest radials form a triangle. The angles should be 120, 30, and 30 degrees (I think). The radials are the same length and the third side is 19 inches. Throwing those numbers into the triangle calculator at:

Calculator.net: Free Online Calculators - Math, Fitness, Finance, Science

Online calculator for quick calculations, along with a large collection of calculators on math, finance, fitness, and more, each with in-depth information.

calculator.net

The radials should be 10.96966 inches each.

View attachment 169748

View attachment 169749

Knowing that, the radials should be tuned (theoretically) to 255.9894 MHz.

Am I correct with all of that? TIA!

Says it packs up at 12 inches, so assuming that's the length of the radials , so I'd say you're pretty darn close

 

[prcguy]

DISCLAIMER: My brain does not function well due to my Encephalopathy caused by MELAS so this may or may not be correct.

According to the drawing in Post #1, the two closest radials form a triangle. The angles should be 120, 30, and 30 degrees (I think). The radials are the same length and the third side is 19 inches. Throwing those numbers into the triangle calculator at:

Calculator.net: Free Online Calculators - Math, Fitness, Finance, Science

Online calculator for quick calculations, along with a large collection of calculators on math, finance, fitness, and more, each with in-depth information.

calculator.net

The radials should be 10.96966 inches each.

View attachment 169748

View attachment 169749

Knowing that, the radials should be tuned (theoretically) to 255.9894 MHz.

Am I correct with all of that? TIA!

Ground radial resonance has nothing to due with the shape they all make together like a triangle, square, hexagon, etc, its their physical length that is important. If they are fixed at one length then they are best used near their 1/4 wave resonance and also their 3/4 wave resonance where a 1/4 wavelength radial will incur a 1/2 wave round trip for RF flowing from the antenna feed point to the radial tip then reflecting back, closely mimicking the feed point impedance. At 3/4 wavelength there will be a 1 1/2 wavelength round trip which will also mimic the feed point impedance.

With ground radials in the 10-12" range you won't be able to get a good match on any amateur band or public service band by tuning the top whip.

 

[K4EET]

Ground radial resonance has nothing to due with the shape they all make together like a triangle, square, hexagon, etc, its their physical length that is important. <snip>

You may have not understood the triangle. It is the Obtuse Isosceles Triangle equation that was used to calculate the radial length to subsequently calculate the resonance quarter wave frequency of the radial.

 

[vagrant]

If a signal using an antenna indoors is slightly wonky, this antenna may help if placed outdoors for temporary use. You know, for strong signal stuff. I'd pay $5 for one just to play with it...and probably modify it. Still, a strong signal doesn't need much of an antenna.

For $65, no F'n way. One would be better served with a telescoping monoband antenna, or even the old RS telescoping 20-006A scanner antenna and adjusting the length as needed. I'm figuring one could be creative enough to figure out a BNC mount for outdoor temporary use. I think these were going for $5 or $10 during the last days. I purchased one decades ago and nabbed a few more during the Radio Shack funeral march.

 

[prcguy]

If a signal using an antenna indoors is slightly wonky, this antenna may help if placed outdoors for temporary use. You know, for strong signal stuff. I'd pay $5 for one just to play with it...and probably modify it. Still, a strong signal doesn't need much of an antenna.

For $65, no F'n way. One would be better served with a telescoping monoband antenna, or even the old RS telescoping 20-006A scanner antenna and adjusting the length as needed. I'm figuring one could be creative enough to figure out a BNC mount for outdoor temporary use. I think these were going for $5 or $10 during the last days. I purchased one decades ago and nabbed a few more during the Radio Shack funeral march.

If your not familiar with Super Antenna, its all real expensive. The scanner ground plane is one of their cheaper items. Check out the price on one of their other products.

Super Antenna MP-1 DXTR80 portable All Brand Antenna Superwhip Brand New | eBay

HF SuperWhip Tripod All Band 80m MP1 Antenna with Clamp Mount and Go Bag. Perfect for Vacation. The TM1 Low Profile Tripod sets up on any flat surface. The #1 HF Portable Vertical Antenna worldwide.

www.ebay.com

 

[vagrant]

I have not used their antennas, but I have a feeling my handful of Lakeview Hamsticks would perform better. Roll out the appropriate length wire as a counterpoise for whichever Hamstick and keep it elevated using my non-insulated walking stick and start having fun.

Still, for VHF/UHF scanner stuff my Comet CA-2XRSR or NMO version mobile antenna works quite well. Still, I have not tried it without a ground plane. Time to test.

 

[a727469]

Ok this us all too complex for my little mind😵‍💫 however the one thing that keeps getting mentioned is the radial length and figuring it. I wonder why this was it not mentioned in the ad itself.
I have made many small ground planes and varied their length from around 13-19 with their telescopic height remaining about 18 for vhf, uhf and frankly unscientifically in the real world for receive, I have noticed no difference. Obviously, everybody’s results may be different.

 

[KevinC]

I suppose an admin or moderator could have simply moved the thread too, it's not like they've never done it in the past.

I was trying to see if I missed something, apparently I didn’t.

Speaking of, check out these speakers…

https://www.amazon.com/Skar-Audio-SDR-10-D2-Subwoofer/dp/B078TNS1TQ