Build a discone for airband?

[edN]

I'm working on building my first antenna, and need the advice of some experts.

I was planning to build using the specs from a diamond discone, but since this antenna will be used for airband only (118-400 MHz) I'm having second thoughts.

I was looking at the test specs here: http://www.strongsignals.net/access...splay&rtype=rev&class=ant&num=002
and noticed the discone is almost dead from 250 to 400 MHz, which is right where I want strong reception.

I found these specs on the net, and thought if I built the antenna to these specs I'd avoid that dead area?

Size of cone and disk is calculated as follows:
L = 2953/F
D = 2008/F
D = diameter of disk inches
L = side of cone inches
F = lowest frequency MHz

I'd appreciate your ideas and input.

 

[TeRayCodA]

Hi,edN;
You are in the right place! I have been doing this for about 20 years.See some of these links of what I do in my spare time.
I listen to 225-400Mhz a lot too!,And, all of these I have built work outstandingly!

http://hometown.aol.com/teraycoda/myhomepage/photo.html

http://www.radioreference.com/modules.php?name=Forums&file=viewtopic&t=18131

http://www.radioreference.com/modules.php?name=Forums&file=viewtopic&t=18427

Any questions,feel free to pm me!
-teray

 

[TeRayCodA]

noticed the discone is almost dead from 250 to 400 MHz, which is right where I want strong reception.

I found these specs on the net, and thought if I built the antenna to these specs I'd avoid that dead area?

Hmmm..no dead area for me here.This seems to be one of the "sweet spots"for mine,as that band is mainly what I listen to.

 

[edN]

teray, those are some nice homebuilt antennas. The pic third from the left on your first link page looks like what I'm trying to build. I have the materials and the skill (I think, lol). I'm just trying to decide what specs to use. What are the element lengths, etc?

 

[TeRayCodA]

Each top element is: 6&1/4"
Each skirt element is 15&1/2"

I made that one from copper tubing,and a piece of brass sheet,that I made a small cone out of to solder the skirt elements onto.

Also,the connector is a barrel type so-238 that I soldered directly on the end of the tubing(removed the insides,before soldering,then put them back,plus a center conductor that runs up to the disc assembly,through the support pipe)12 awg copper wire.

 

[N_Jay]

I don't get how he did the test.

It s seems he ued his "S" meter as teh indication of signal strength, but did not attempt to calibrate it at all.

He makes no mention as to the source signal he used or how it was "calibrated".

I would not put too much credibility on the test.

Discones are wel documneted designs. You can get the calculations and the expeced results many places.

 

[edN]

I don't get how he did the test.

It s seems he ued his "S" meter as teh indication of signal strength, but did not attempt to calibrate it at all.

He makes no mention as to the source signal he used or how it was "calibrated".

I would not put too much credibility on the test.

Discones are wel documneted designs. You can get the calculations and the expeced results many places.

Thanks for your input. N_Jay. So you're saying the test was invalid, or what?

I only *use* a radio or an antenna, so I'd like to know. Strongsignals was referred to me me as a reliable source of information.

Would you post a link to one those places? Or, send me a PM.

Thanks, Ed

 

[N_Jay]

I don't get how he did the test.

It s seems he ued his "S" meter as teh indication of signal strength, but did not attempt to calibrate it at all.

He makes no mention as to the source signal he used or how it was "calibrated".

I would not put too much credibility on the test.

Discones are wel documneted designs. You can get the calculations and the expeced results many places.

Thanks for your input. N_Jay. So you're saying the test was invalid, or what?

I only *use* a radio or an antenna, so I'd like to know. Strongsignals was referred to me me as a reliable source of information.

Would you post a link to one those places? Or, send me a PM.

Thanks, Ed

Not saying its "invalid", just saying that what is posted does not give me confidence in its validity.

http://www.wb0w.com/arrl/Antenna_Trans.htm
http://www.northcountryradio.com/Articles/discone.htm
http://www.hard-core-dx.com/nordicdx/antenna/hidden/indoor.html
http://www.ramseyelectronics.com/downloads/manuals/DA25.pdf

Google is your friend.

 

[PointMan]

TeRay have you thought of building stacked di-poles for the Mil Air band? Theyre suposed to be fairly broad banded right? It seems logical that the reception would probably be fairly improved over a discone, even at the far edges of the Mil Air band.

 

[TeRayCodA]

No,the only stack dipoles I have are for my MURS radio.Correct me if I'm wrong,but does'nt the discone work better for Air/ground comms?-radiation pattern?(I dunno,I just build 'em,and I like them!)

 

[N_Jay]

No,the only stack dipoles I have are for my MURS radio.Correct me if I'm wrong,but does'nt the discone work better for Air/ground comms?-radiation pattern?(I dunno,I just build 'em,and I like them!)

Discone does have the bandwidth and pattern that is well suited for air comms.

Lots of other designes of antennsa will work well also.