Better performance from a imax.

[King Mudduck]

Other than trashing it is there any ways to improve the performance of this antenna?I live on top of a hill so im in a really good spot.However,would i see any increse in receive or transmit if i went with a ground plan kit or if i put it up higher than it is now?Right now its sitting on an 11 foot pole so its not that high(i have it grounded out the wazzu and my swr is 1.3 so no its not a halfass install).The reason i did not go higher is because like i said my house sits on top of a hill and i did not think that it was worth the trouble to higher.I dont have a problem talking or hearing but i just wanted to know if there was anything else to do to make it better?

 

[351_bear]

getting out better

you need to go at least 30 feet for it to be efficent 60 feet would even be better I'd goto eather home depot or lowes and buy 3 ten foot sections of pipe make sure that when you buy the pipe its one size bigger on each piece so it fits inside of each pipe drill holes on the bottom of each pipe take some nuts and bolts and insert in each hole then you have a push up pole if you don't think its gunna be sturdy enough use a 5 gallon bucket fill it with concrete and put the pole inside of it and burry it

 

[Master Chief]

This antenna was designed to work without a ground plane. The companies who want to sell you one are (IMHO) more interested in getting your money than they are in increasing your performance.

Minor tests on a Maco V58 with relation to the distance between the ground plane and the tuning loop has been interesting to say the least. This test has been nothing more than moving the ground plane up and down the base assembly to see how it affects SWR and bandwidth readings. Future tests will include field strength and radiation angles.

What this simple test has taught me is that ground plane orientation does affect the performance of an antenna. You just can't add one or subtract one without changing something.

Tests have been done by KG6AOH with the ground plane kit on the A-99 and I believe the imax 2000 that didn't show much improvement.

If you want to improve the performance of your antenna, get it at least 18' above the ground with higher being better. Also, use a QUALITY coax. I suggest LMR-400 or CableXperts' CXP1318FX.

As always, you will hear from people who will say the addition of the ground plane "significantly" increased their performance. Its hard to argue their findings without witnessing it yourself. Some of these same people will also tell you that the "back door kit" for the Moonraker IV and the PDL-II also improves performance, but as we know, this is not true.

If YOU want to know for sure, buy the ground plane kit and install it on your antenna. Take before and after readings. Keep an open mind! If you find that there is not a performance increase, then you can alwas sell the ground plane kit to someone else who is convinced that this is the way to go; there is one born every minute!

Remember, the BEST money you can ever spend on a radio system is on the antenna and feedline!!!!

 

[Master Chief]

I have read that one should have the feed section of the antenna at 36ft then 72ft and so on. It has something to do with the wave length. I'm not sure how true this is, maybe someone else who knows will chime in.

With a ground plane antenna, the ground plane elements just below the verical element simulates the earth, as far as the antenna is concerned. Having an antenna a full wave or two full waves is another bit of lore found out here.

Tests have show that you want to be at least 1/2 wave above the ground to reduce or eliminate any "ground effects". After that, the higher the better!

With that being said, if you have a horizontal beam antenna, the rules change completely! Height above ground WILL change your take off angle. There is a sweet spot depending on where you want your signal to end up and the current atmospheric conditions. You can actually be TOO HIGH sometimes!

So, for vertical omnis, 18' minimum and the higher the better. For horizontal beams, height above ground can change everything.

 

[Keep-it-real]

Don't waste your money.....

 

[freecell]

ahh yes, the world according to MC........
pay particular attention to what happens to both gain and TO angle at the various heights relative to wavelengths above ground referenced to the feedpoint for the listed soil types in antennas modelled in our neighboring 10M band.

get the feedpoint at least 1 wavelength above ground and ignore the detractors.

http://www.firecommunications.com/10mvtest.txt

 

[King Mudduck]

Alot of good info here!Thanks all.

 

[freecell]

at a 0.5-wavelength over poor, good or very good soil types takeoff angles of 45 degrees would be great for NVIS operation when the MUF reaches 27 Mhz. FYI.

 

[Master Chief]

ahh yes, FC is missing the mark once again........

Monopole antennas are fun! I've worked on really big ones and some small ones. The ground radial systems are fun too.

However, a GROUND PLANE antenna is different than a monopole with or without a ground system.

Your referenced text (by the way, is that your work or someone else's? It looks like L.B's.) does not speak to a ground system at all. Oh, and so we are clear, I'm not disputing the numbers when speaking to monopoles.

I spoke about GROUND PLANE antennas and HORIZONTAL BEAM antennas. You spoke about MONOPOLE antennas.

NVIS antennas are fun too. Usually they are horizontal dipoles or loops with radiation at very steep angles. They are usually used on lower frequencies (80/75, 40) I've never seen or even heard of a vertical NVIS antenna with a radiation pattern of 45 degrees on 21-30 Mhz. Not that this has ANYTHING to do with the topic at hand anyway.

FC, your passion for me is getting old. Please find someone else to play with. Thank you.

 

[freecell]

SMD........

off-center fed vertical monopoles with radials........

 

[Master Chief]

Thanks for clearing that up. See, it IS L.B's work. I knew I've seen it before!

http://www.cebik.com/amod/amod79.html

(You really should give L.B. credit when you steal information off of his site. My discussions with him tells me he probably wouldn't mind as long as due credit was given. He really is a nice guy!)

 

[bob85]

i can feel a sigma iv 7/8 moment comming on guys :twisted:

 

[freecell]

no, and i'm not going to give any classes in copyright infringement law either.

 

[Master Chief]

Hi Bob! you da' man! No no no, I do not wish to discuss or argue any point with FC ever again. Its just not worth it!

I'll be the first person to admit when I have something wrong and always open to criticism. I'll also give credit where credit is due and always thirsty to learn! I've even learned a few things from FC.

But, when attacked by FC, I'll just keep quiet and smile. It took me a while, but its like wrestling pigs in the mud, after a while you realize they like it!

How is that I-10K working out for you?

 

[freecell]

i think he wandered off into another part of the forum........