mobile antenna to base !

[Mudfoot]

They are also sold in 108" lengths in the USA.

...and have for many years.

 

[w9cll]

They are also sold in 108" lengths in the USA.

...and have for many years.

Well its been years since i looked for one.

 

[stathis]

this set up is good or i have to improve something ?? swr tx ??

 

[gamegetter]

hello !! yesterday i made a dipole , i tune it my swr about 1.1 it works well my range about 4000 miles my question is can i use an amp on the dipole ??

yes, you can run amp through your dipole.

 

[gamegetter]

this set up is good or i have to improve something ?? swr tx ??

a dipole is a great antenna, most often it is under rated and it is not far from a 3 element beam in terms of s units, the design is simple, they are easy to construct and put up and work great dx in the horizontal much like a beam.

if you want to talk local, make another one as simple as they are and run it vertical and or in a inverted v config-google and research those set ups or ask away.

remember your ability to talk dx is largely dependent on mother nature as such a basic set up is all that is needed when conditions are in your favor.

best of luck enjoy the hobby.

 

[W5LZ]

Lets get something straight. A dipole if=s a good antenna, but they don't do 'miracles'. A dipole can be put up as a horizontal of a vartical antenna. Nothing special about that. They can work well in either polarity, alsop nothing special about that. A dipole antenna is the basic/standard. They give you a basis for com[arison to other antennas.
That typically means that while they do work, there are other types of antennas that will do 'better'. Don't think that there's anything special about them, there isn't.
A half wave dipolw ia the basic antenna, what all the rest of them are compared to. it's good, but there are better ones for particular purposes.
A dipole amtenna is a good basic antenna. The key word there is 'basic'. It's a good way to estanblish the 'basic' performance. If you need or want more than that then you have a lot of choices, but all of those choices are based on a dipole.
There aren't any 'miracles' antennas no matter what you may think, or what people say.
Howz that that for a 'new' idea?
Lot's'a 'catches'/'buts' with that, but it's the bottom line.
-' Doc

 

[stathis]

a dipole is a great antenna, most often it is under rated and it is not far from a 3 element beam in terms of s units, the design is simple, they are easy to construct and put up and work great dx in the horizontal much like a beam.

if you want to talk local, make another one as simple as they are and run it vertical and or in a inverted v config-google and research those set ups or ask away.

remember your ability to talk dx is largely dependent on mother nature as such a basic set up is all that is needed when conditions are in your favor.

best of luck enjoy the hobby.

I live in greece so we always the sun is sine and we have about 35 celcioum
degre !! D so i have good swr when the sun is sining the problem is when its raining

 

[Marconi]

You can use any mobile antenna as a base, best idea is to get it mouted on top of a 20 ft + pole, then add 3 or 4 evenly spaced wires about 108" in length at approx 40-45 degree angle.to the ground side of the mount,

then trim each equally in small amounts to get best swr, will work almost as well as a Starduster m400.

for the last time because i'm sick of saying it, please stop recommending 102" whips, they are too short for any cb frequency between 26 and 28 mhz, they are more suited to the 10m band. cb whips vary from about 103" to 107" when resonant depending on where you set centre frequency for. thats the reason most people need a shorted spring to resonate them.

this myth is almost as bad as A99 9.9Dbi gain. I've showed the maths time and time again for this, and even if The DB is right and I wrongly use the .98 velocity factor instead of no velocity factor which he supports, that would make them even longer when resonant and 102 " whips even shorter than they should be. :bdh::bdh::bdh:

Jazz, IMO the 1/4 wave radiator has a somewhat unique characteristic about it...it needs a suitable ground plane in order to work right. When we apply horizontal radials for the CB range we can obtained resonance with a whip radiator and whip radials that are close to .125" in diameter, and lengths at or near 105" - 109" inches...just like you claim.

However, when we use either 102" or 108" inch horizontal whips for the radials...we don't get a good match in such cases. So, we use the Starduster idea and slant the radials down some...in order to see a better match. As we move the radials down in angle, the resonant length for the 108" radiator and radials needs to get shorter and shorter the further down we go.

The best performance and match I've found using both Eznec and my VA1 antenna analyzer on my real world Marconi antennas...is with a 102" whip radiator, and 102" whip radials with their angles at about 17* - 21* degrees out from the mast.

This is also noted in the Starduster patent #4208662 where it states the best radial angles are 12* - 25* degrees. See the front page of the patent below: https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US4208662.pdf&pli=1

So, I can't agree with your following statement:

for the last time because i'm sick of saying it, please stop recommending 102" whips, they are too short for any cb frequency between 26 and 28 mhz, they are more suited to the 10m band. cb whips vary from about 103" to 107" when resonant depending on where you set centre frequency for. thats the reason most people need a shorted spring to resonate them.

Jazz, I might agree with your claim in the case with mobile installs...where we have a particularly bad ground plane to work with...and that might be mostly in the horizontal plane. It is hard to tell what the radiator really sees as the ground plane on a mobile.

I recommend the 102" inch mobile whips for building 1/4 wave base antennas with a good 102" inch whip ground plane. <gotproof><gotproof><gotproof>

 

[gamegetter]

I live in greece so we always the sun is sine and we have about 35 celcioum
degre !! D so i have good swr when the sun is sining the problem is when its raining

I can only imagine how beautiful Greece can be with it's long coast lines, many islands and rich history, being the birth place of democracy.


As for the rain/water swr, the rain can have an effect on your antenna in and of itself let alone if it gets inside of it.

You can use electrical tape in addition to silicone to wrap coax connection and any other areas where water may get in. On the connector for example, wrap electrical tape from bottom up so that a layer is formed allowing water to run off. Then add another layer of silicone on top of it. Others have used varnish and etc.

there are several ways to keep water out, others will have more input.

 

[W5LZ]

" Originally Posted by Jazzsinger
for the last time because i'm sick of saying it, please stop recommending 102" whips, they are too short for any cb frequency between 26 and 28 mhz, they are more suited to the 10m band. cb whips vary from about 103" to 107" when resonant depending on where you set centre frequency for. thats the reason most people need a shorted spring to resonate them."
What most people don't take into consideration with those 102" whips is that the mount has to be added to that 102" length to get it's total length. The antenna starts where the feed line ends. If the mount is 2 inches tall then the total length if 104", not 102". A typical ball mount is 3 to 4 inches 'tall' depending on how it's used. So, that 102" whip turns into something like 105 to 106 inches tall.
- 'Doc

 

[fridayjoefriday]

Seeing how this tread is still advancing, question for Marconi. Post 29, this tread, you have a image of an mobile antenna mount with an A99 ground plane hub below it. I have a 8.5 foot ss whip with two radials about 45 degrees down slope. According to your post, I should add a third radial wire, correct?

 

[Marconi]

Seeing how this tread is still advancing, question for Marconi. Post 29, this tread, you have a image of an mobile antenna mount with an A99 ground plane hub below it. I have a 8.5 foot ss whip with two radials about 45 degrees down slope. According to your post, I should add a third radial wire, correct? BTW how does one add images?

I checked my notes for your idea with 2 x 102" whip radials and 1 x 102" whip radiator, and I found my antenna produced a very good match...when the radials were slanted down at or below 45* degrees.

In testing at about 36' feet high I did not see a detectable difference even when I made the antenna with 4 radials. Even if there was an advantage I could not detect the small difference in RX signals. I did not compare TX signals however.

Do a search on this forum and maybe somebody has posted instruction on how to add images.

 

[Riverman]

I've been gone a few months but have now returned. As you might remember, I enjoy making homemade antennas that aren't always practical. Here are my two questions:


1. I understand that if using a full-length steel whip for the vertical, the radials need to be slanted downward at about a 45 degree angle to get the proper impedance. If, however, I use a base-loaded antenna as my vertical element (i.e. Wilson 1000, K40, etc.), do the radials still need to be slanted or can they be horizontal?

2. Will steel whip radials shorter than full-length work? (i.e. 62 inch replacement whips for the Wilson 1000).

Thanks! Hope all of you are doing well these days.

 

[The DB]

Angling the radials down increases the feedpoint impedance, bringing the feedpoint impedance of a 1/4 wavelength groundplane antenna closer to a good SWR match.

When you use a loaded antenna the feedpoint impedance is even lower than a full length antenna, thus requiring angling the radials even more to raise the impedance to a given point, assuming the vertical part of teh antenna hasn't been shortened to 3 feet or something like that, which you likely won't be able to raise the impedance enough to get a match to begin with.

Radials that are to short? Well, most cars are essentially to small a ground plane and antennas work on cars, even shortened ones. You may also consider using radials that have loads on them as well... In either case shortened radials will lower the feedpoint impedance...


The DB

 

[Riverman]

Thanks, D.B.

Sure glad I asked or I'd had a Wilson 1000 up with horizontal radials.

Guess I'll go with a 102" steel whip for the vertical and wire for the radials.

Never have fully understood resonance.

How do I know when I have the radials angled properly without an antenna analyzer? Is SWR a good indicator?