mobile antenna to base !

[The DB]

Let me ask this, my a99 is roughly 36ft to tip, would adding the gpk kit benefit me in any way? Or is the gain if any that minimal as to justify the purchase? I can't lift the antenna any higher due to HOA crap. So it is as high as I can go. Maybe another 10ft most I could go, but it would require a lot of work just for that. I also plan on upgrading antenna soon. Suggestions for one that will work well at this height and not make the neighbors cringe lol. Thanks for any responses. God bless and have a great one.

According to the models I posted several pages back (yesterday morning and now we have several pages since? Wow...), the difference in gain on the a99 from adding the ground plane kit is about 0.14 dB, give or take depending on the environment in your area. You will never notice that difference. If you see a difference somewhere it is far more likely to be because of fewer common mode currents as the radials tend to absorb some of the power that would otherwise go towards said currents.

From playing with the models, I believe the gain is from the radials changing the impedance of the antenna itself, getting it closer to a good match. I say that because when looking at the current distribution of that model, the current on the radials never gets above the lowest measured rating, so there are essentially no currents on said radials compared to elsewhere on the antenna. Adding those radials, however, has a noticeable effect on the antennas feedpoint impedance. This, however, requires a retune to take advantage of.

The starduster design at the same tip height actually has more gain than the a99 in any configuration, and that is before you factor in the additional losses of the a99 because of its lossy matching system, but you do need an additional amount of mast to get said antenna to the same tip height... The starduster is also not quite as tall as the a99 because part of it is angled, and it doesn't have the additional 2 foot aluminum tube at its bottom.


The DB

 

[357magnum]

Thanks for that post DB I also have been tossing the idea around about adding the ground plane kit to my A-99 you just made up my mind for me for what the kit cost I'm better off changing the whole set-up !

 

[Lil'Yeshua]

And the Starduster is 16.535 feet (16 feet 627⁄64 inches) total height. Beat the pants off a A99 you say?
http://www.sirioantenna.com/index.php?main_page=product_info&cPath=2_18&products_id=188
Radials are 8.825 feet (8 feet 929⁄32 inches) in length

 

[222DBFL]

Yep time for an antenna upgrade!! Thanks Lil yeshua and DB!! Much appreciated. I was going to try and get my current setup higher, but upon reading your post and lil yeshua's posts, a new antenna would be the best best! Again thanks for all the info, it's much appreciated. Have a great day and god bless.

 

[Riverman]

http://www.eagle1com.com/storepp/antehardware/anteh-other.htm

How does this thing attach to the mast?

 

[Lil'Yeshua]

How does this thing attach to the mast?

Beats me. Maybe you can call or email Eagle One and find out.
Let me revise that. There looks like a set screw hole on the side of the hub.
The center joke is made for stud type mounts so there may be a need for a mounting bracket.

 

[The DB]

Beat the pants off a A99 you say?

That language may be s bit to strong, but if you can match tip heights "has more gain than an a99" would be accurate...


The DB

 

[Lil'Yeshua]

That language may be s bit to strong, but if you can match tip heights "has more gain than an a99" would be accurate...


The DB

Even with the gain figures Marconi did for my A99?

 

[Riverman]

Cane Pole GP

Just had an idea.

10 ft cane/bamboo fishing pole (5 bucks at Walmart) attached vertically to my 15' mast with hose clamps. 108 inches of copper wire connected to center connector fo coax running length of pole. Another 108 inch copper wire attached to coax shield angled downward at 45 degrees attached to top of wooden fence (with insulator and rope).

Trim as necessary for SWR.

Now I have my 1/4 wave single radial GP for the cost of a cane pole and 20 feet of copper wire rather than buying a 102" steel whip or 7 ft Firestik as I was planning. Plus a heavy duty stud mount.

Thoughts?

 

[Lil'Yeshua]

Don't forget to clear coat it. I thought of the same thing sometime back. Don't know about it being resonant though.

 

[binrat]

Just had an idea.

10 ft cane/bamboo fishing pole (5 bucks at Walmart) attached vertically to my 15' mast with hose clamps. 108 inches of copper wire connected to center connector fo coax running length of pole. Another 108 inch copper wire attached to coax shield angled downward at 45 degrees attached to top of wooden fence (with insulator and rope).

Trim as necessary for SWR.

Now I have my 1/4 wave single radial GP for the cost of a cane pole and 20 feet of copper wire rather than buying a 102" steel whip or 7 ft Firestik as I was planning. Plus a heavy duty stud mount.

Thoughts?

Sounds like it should work. I would use insulated wire and at least 3 ground radials.

Sent from my GT-S5690M using Tapatalk 2

 

[Lil'Yeshua]

All Fishing Buy Guide, Fishing Rods Materials, Bamboo, Fiberglass, High Modulus Japan Graphite Carbon.

 

[Riverman]

Here's what I had in mind.

B & M Company 10' Jointed Bamboo Fishing Rod - Walmart.com

Don't know how strong it will be. Can always get a cheap fiberglass one if this one breaks.

I wouldn't know a resonant antenna if I tripped over one. Never have understood that term.

 

[Riverman]

Hey, I'm serious about the resonance remark. I really don't have a clue.

Can someone tell me what that means and how do I know if my antenna is resonant if I don't have an antenna analyzer?

I've asked this before with no response. Can someone please help me?

Thanks.

 

[The DB]

Hey, I'm serious about the resonance remark. I really don't have a clue.

Can someone tell me what that means and how do I know if my antenna is resonant if I don't have an antenna analyzer?

I've asked this before with no response. Can someone please help me?

Thanks.

Think of a guitar string. You pluck it and it vibrates at a certain frequency. That is the resonant mechanical frequency of the guitar string.

With an antenna we are not looking for a mechanical frequency, but an electrical resonant frequency, but it is still the same concept, just applied a little differently.

Let me try and explain further, there are two types of "reactance", and the combination of those determines the antennas resonant frequency. The two types of reactance are inductive and capacitive.

If you take an antenna and add inductive reactance it is like adding length to the antenna, or adding length to the guitar string in the example above, they resonate at a lower frequency.

If you add capacitive reactance it is like shortening the the antenna or the guitar string in the example above. This is seen on the guitar when holding the strings when plucking them. Both of these cases leads to raising the resonant frequency.

In short, when working with antennas, resonance is the frequency at which inductive and capacitive reactances are in balance, or add up to 0.

How do you find resonance without an antenna analyzer?

If you are looking for directions for using just an SWR meter, I'm sorry but that isn't possible. With an SWR meter you have an end result of the combination of impedance and reactance, but it doesn't, on its own, have the ability to determine how much of either are causing the SWR it is measuring, as I said above, it can only measure the end result.

I suppose you could use something like a grid dip meter, but those are dated technologies... Here is a picture of one of mine. I have used this one and its resonance results are very close to, but not exactly equal to, my $600 VNA.

This is an old technology, although I know MFJ still makes a dip meter for about $150...

MFJ Enterprises Inc.

There is also something called a noise bridge. These work by putting out wideband noise, and the frequency that has the least amount of noise (called the null) is the resonant frequency. MFJ makes one of these as well for about $80...

MFJ Enterprises Inc.

Really though, neither of these technologies is as good as an antenna analyzer that can read reactance.

Another option you may have, if you only need to be able to tune antennas, is called a field strength meter. These don't care about impedance and reactance, they simply measure the radiated signal in the area and give a reading. To use one you simply make a change to the antenna and then see if the radiated signal has increased or decreased, and keep tuning until you find the strongest field strength... MFJ sells a few of these as well, and they are cheaper than anything mentioned above, about $30 for a cheap one.

I also recommend purchasing a field strength meter and using it a few times before getting an antenna analyzer. They will help break common notions about SWR that many people who get antenna analyzers really fight giving up, and those notions actually hold people with antenna analyzers back from getting the best tune in their antennas. Also, you can tune an antenna about as well with a field strength meter as you can with an antenna analyzer... With an antenna analyzer you are tuning an antenna based on variables, with a field strength meter you are tuning an antenna based on actual measurements of radiated signal.


The DB