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mobile antenna to base !
- Thread starter stathis
- Start date
We should be careful not to confuse antenna gain with angle of radiation because while both can effect distant signals, the cause behind each of the two is entirely different. Years ago I did a test between a 102 whip and the 7 foot Skip Shooter which has a similar design as the KW7.
The differences were very hard to distinguish between however, the 102 inch whip consistently had a slightly better local signal (line of sight). On the other hand, I was convinced the Skip Shooter was making stronger skywave contacts which seems to support the claims made in the Firestick ad.
Granted, testing antenna performance with skywave propagation is probably one of the most difficult methods to do with accuracy. When you switch between the two antennas enough and have other vehicles in the same parking lot attempting to make the same contact that are not making any changes, you get a sense of what's going on.
No one is going to claim that taking 3 wires in parallel that are electronically equal in length to a 1/4 wave but helically wound will produce improved gain. We should think twice before we are sure this could not alter the angle of radiation this antenna develops over the vehicles ground plane in such a manner that could be an advantage in skywave.
The differences were very hard to distinguish between however, the 102 inch whip consistently had a slightly better local signal (line of sight). On the other hand, I was convinced the Skip Shooter was making stronger skywave contacts which seems to support the claims made in the Firestick ad.
Granted, testing antenna performance with skywave propagation is probably one of the most difficult methods to do with accuracy. When you switch between the two antennas enough and have other vehicles in the same parking lot attempting to make the same contact that are not making any changes, you get a sense of what's going on.
No one is going to claim that taking 3 wires in parallel that are electronically equal in length to a 1/4 wave but helically wound will produce improved gain. We should think twice before we are sure this could not alter the angle of radiation this antenna develops over the vehicles ground plane in such a manner that could be an advantage in skywave.
I started using that frequency because it is easier to calculate lengths for it. In the 4nec2 modeling software it comes out to exactly 10 meters in length. When I use that frequency I do scale my CB antenna lengths to match it, such as the 6 foot shortened angled radials in that a99 model, and the 2 2 foot section of tubing at the bottom of the a99 antenna, ect. are all shortened to account for scaling.
Its just habit on my part I guess.
The DB
Riverman71,are you planning on using your horizontal dipole but with longer elements? The SS 102" whips will droop a bit and you might need a balun. The Firestik 7kw will add some horizontal stiffness.
DB,
The quote saying the KW7 outperformed the steel whip came from this site:
Copper Talk: Fire Stick
I did take it with a grain of salt. My only reasons for considering the KW7 is that it might not wave around as much in high wind (which we have a lot of here), and since it is top loaded, I might gain some height (in theory) in my installation (I just have a 15' mast so every inch in important).
The quote saying the KW7 outperformed the steel whip came from this site:
Copper Talk: Fire Stick
I did take it with a grain of salt. My only reasons for considering the KW7 is that it might not wave around as much in high wind (which we have a lot of here), and since it is top loaded, I might gain some height (in theory) in my installation (I just have a 15' mast so every inch in important).
Here's something ready made that can provide about the same if not better performance IMO.
http://www.sirioantenna.com/index.php?main_page=product_info&cPath=2_18&products_id=188
Use it in a vertical orientation. Yes you will gain some height but you need to need some type of ground plane to make it work properly and maybe some type of rf choke or else the mast and coax will act as the other half of the antenna and perhaps inviting common mode currents into the radio room.
I'd love to have the StarDuster but with my 15' mast insn't tall enough to keep the radials off my roof.
If I go with the gp using the KW7 or steel whip, I'll only be using a single radial (either wire or another antenna) slanted downward pointed away from the eave.
I've seen postings from Marconi showing such an antenna (a single radial) will perform surprisingly well.
If I go with the gp using the KW7 or steel whip, I'll only be using a single radial (either wire or another antenna) slanted downward pointed away from the eave.
I've seen postings from Marconi showing such an antenna (a single radial) will perform surprisingly well.
Workman sells a hub that has 3 3/8 X 24 threaded slots for downward sloping radials. It has a 1/2" pre-drilled hole at the top so you mount a stud and then use whatever vertical radiator you choose. Has anyone used one of these?
I just purchased a few of the Workman hubs and some stainless steel studs. I've got a collection of stainless steel 102" whips, 6' whips and others. It is too hot outside now, but I'm inclined to do a little experimenting come November.
I just purchased a few of the Workman hubs and some stainless steel studs. I've got a collection of stainless steel 102" whips, 6' whips and others. It is too hot outside now, but I'm inclined to do a little experimenting come November.
That's it.
Based on the plots The DB posted 2 pages back, I'd use my stainless steel Radio Shack 102" as my vertical radiating element and the 6' whips (A99 top sections) for the ground plane radials.
Based on the plots The DB posted 2 pages back, I'd use my stainless steel Radio Shack 102" as my vertical radiating element and the 6' whips (A99 top sections) for the ground plane radials.
The only plot I used shortened 6 foot radials was with the a99.
If I were to use shortened radials on an antenna that does not have a matching network, like the one being discussed, I would use loaded CB antennas as opposed to 6 foot lengths of antenna with no load to maintain the antennas resonance.
The a99 has a matching network built into its design, which can be used to tune both the antenna and the radial system together. The 6 foot radials were only used with the a99 models, and not the starduster models.
You don't have to have the radials angled that steeply, you can have them angled at 45 degrees or even higher, just not so high that they are angled up...
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.