Cecil Moore wrote:
RST Engineering wrote:
(By the way, you are operating close enough to the third harmonic of
144 on 440 that the antenna will perform quite well on both frequencies.)

It will even perform well as a satellite antenna on
440. EZNEC says it has a TOA of about 45 degrees.

Hmmm. In some cases, would be nice to keep more of that signal terrestrial.

Regards,
JS

That's why you bend the radials down at a 45. It bends the pattern right
along with it.

Jim



"John Smith I" wrote in message
...


Hmmm. In some cases, would be nice to keep more of that signal
terrestrial.

Regards,
JS

John Smith I wrote:
Cecil Moore wrote:
RST Engineering wrote:
(By the way, you are operating close enough to the third harmonic of
144 on 440 that the antenna will perform quite well on both
frequencies.)

It will even perform well as a satellite antenna on
440. EZNEC says it has a TOA of about 45 degrees.

Hmmm. In some cases, would be nice to keep more of that signal
terrestrial.

That's the subtle point I was trying to make. To keep
the TOA low, the antenna should not exceed 5/8 WL.
6/8 WL raises the TOA. That's not optimum for hitting
repeaters unless they are on very high, very close
mountains.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
...
That's the subtle point I was trying to make. To keep
the TOA low, the antenna should not exceed 5/8 WL.
6/8 WL raises the TOA. That's not optimum for hitting
repeaters unless they are on very high, very close
mountains.

Cecil:

OK. No problem, subtle is all yours ...

But, remember, I get sarcastic and blunt! evil grin

Regards,
JS

Jim wrote:
You are not asking for the moon. What you want is a simple, compact,
reliable antenna for both 144 and 440 MHz.. Having done a fair amount of
that sort of RACES/ARES stuff, here's what I'd advise you.

Go down to your local radio parts store, Rat Shack if that's all you've
got
and get yourself a female BNC chassis connector (UG-1094, RS # 278-105).
Get a couple of quality male BNC cable connectors while you are at it.
Unfortunately for you, RS doesn't sell anything but that twist-on
solderless
crap for male BNC, so you may wind up buying them mail order.

Get yourself four 3/8" solder lugs and five 19" pieces of solid #14 copper
wire (strip house romex if you have to).

To each of the four solder lugs, solder one end of the #14 wire. These
will
be the four ground plane wires. THe fifth piece of #14 will connect to
the
solder cup on the bottom of the female BNC chassis connector to become the
radiating element.

Now put those four solder lugs over the radiating element and over the
threads on the connector. Use the nut that came with the connector to
fasten the solder lugs, each at approximately 90° from each other (a small
crescent wrench or dedicated 1/2" wrench needs to be part of your
permanent
tool kit). Bend them down at about a 45° angle.

Take the two male connectors and make an RG-58 cable to run from your
radio
to where you want to put your antenna. Connect one end of the cable to
your
radio and the other end to the UG-1094 connector.

You want to move the antenna? Disconnect the cable. Grab your wrench and
pull that nut off. Take off all 4 ground plane wires. Bundle them up
around the radiating element. Reassemble in the new location. Ten
seconds
up, ten seconds down.

You want to use it in the field outside? Bend a small hook (no more than
1/4" long) in the radiating element. Tie a roll of heavy twine to the
hook
and bend the hook shut. Take the roll of twine and throw it around the
highest tree limb you can find. Hoist that sucker up and you are on the
air.

We can dick around with a mounting bracket on the UG-1094 threads if you
want to make a permanent installation out of it.

(By the way, you are operating close enough to the third harmonic of 144
on
440 that the antenna will perform quite well on both frequencies.)

Jim

I agree -- Chuck isn't looking to work big DX so, a complicated antenna is
not needed. Another simple concept is a vertical dipole. Here's an
illustration from "Simple, Low Cost Wire Antennas for Radio Amateurs", by
William I. Orr and Stuart D. Cowan: http://tinyurl.com/yzydbo
The bottom section connects to the shield of the feedline. If made from
tubing, it will act to decouple the outer surface of the shield. If cut for
144-148MHz (38-39" overall length), it will work at 432-444MHz as well. To
make it portable, use stiff wire (welding rod, etc) for the top half, and
schedule-40 ½" copper tubing for the bottom half. An insulated coupling can
be fashioned from wood or plastic dowel or plastic pipe. More dowel or
plastic pipe can be used as a carring handle. Like the ground plane, it can
be suspended from an overhead support. It can also be slipped into/onto a
baseplate if you don't have an overhead support available: nonmetallic
umbrella stand, heavy flower vase, etc. With the exception of the feedline,
your home improvement box store will have all the parts you need.

Bryan WA7PRC

Bryan wrote:
...


You remind me. I have built those antennas, long ago, in the past for
10M+ bands.

If I remember correctly they were termed "bazooka antennas." I kind of
remember there was a recommended ratio of coax shield dia. to inside
diameter of the sleeve--possibly the ratio of the radiating element
figured into securing a 50/75 ohm match also?

You have any more data on that antenna?

Warmest regards,
JS

Thanks. I appreciate the suggestion, but I have built the antenna you
described, using welding rod, plus a 440 MHz (smaller version), but in a
crowded room the radials stick out farther than I want. I tried building a
TV antenna line J-Pole today, but the SWR was higher than I expected. I
haven't tried shortening it yet, but will when I get time. But I would
still have to find some way to hang it from the ceiling or something. I
really want something small, unobtrusive and cheap and easy to build.

"RST Engineering" wrote in message
...
You are not asking for the moon. What you want is a simple, compact,
reliable antenna for both 144 and 440 MHz.. Having done a fair amount of
that sort of RACES/ARES stuff, here's what I'd advise you.

Go down to your local radio parts store, Rat Shack if that's all you've
got and get yourself a female BNC chassis connector (UG-1094, RS #
278-105). Get a couple of quality male BNC cable connectors while you are
at it. Unfortunately for you, RS doesn't sell anything but that twist-on
solderless crap for male BNC, so you may wind up buying them mail order.

Get yourself four 3/8" solder lugs and five 19" pieces of solid #14 copper
wire (strip house romex if you have to).

To each of the four solder lugs, solder one end of the #14 wire. These
will be the four ground plane wires. THe fifth piece of #14 will connect
to the solder cup on the bottom of the female BNC chassis connector to
become the radiating element.

Now put those four solder lugs over the radiating element and over the
threads on the connector. Use the nut that came with the connector to
fasten the solder lugs, each at approximately 90° from each other (a small
crescent wrench or dedicated 1/2" wrench needs to be part of your
permanent tool kit). Bend them down at about a 45° angle.

Take the two male connectors and make an RG-58 cable to run from your
radio to where you want to put your antenna. Connect one end of the cable
to your radio and the other end to the UG-1094 connector.

You want to move the antenna? Disconnect the cable. Grab your wrench and
pull that nut off. Take off all 4 ground plane wires. Bundle them up
around the radiating element. Reassemble in the new location. Ten
seconds up, ten seconds down.

You want to use it in the field outside? Bend a small hook (no more than
1/4" long) in the radiating element. Tie a roll of heavy twine to the
hook and bend the hook shut. Take the roll of twine and throw it around
the highest tree limb you can find. Hoist that sucker up and you are on
the air.

We can dick around with a mounting bracket on the UG-1094 threads if you
want to make a permanent installation out of it.

(By the way, you are operating close enough to the third harmonic of 144
on 440 that the antenna will perform quite well on both frequencies.)

Jim









"Chuck James" wrote in message
t...
I know I could just go buy a mag-mount mobile antenna, but would it be
possible or even practical to build a J-pole type or vertical (without
long radials) antenna for 2m/70cm, out of welding rod, which could be
small enough to be easily portable and used inside different rooms? Our
local RACES is trying to set up a volunteer communications network inside
several different city and county offices to assist in emergencies. I
have searched (a little) for such a design, and found something similar,
made out of TV line, but would prefer something that could be made free
standing and as small as practical. The Welding Rod antennas made with 45
degree radials are a little bulky to move through congested hallways. The
idea is to make it portable enough to move from room to room as needed.
Long radials would impede moving through hallways.
Thanks in advance, KE5GEO

This looks like what i am asking for, but the picture is not very clear.
Any more details anywhere?

"Bryan" wrote in message
...
Jim wrote:
You are not asking for the moon. What you want is a simple, compact,
reliable antenna for both 144 and 440 MHz.. Having done a fair amount of
that sort of RACES/ARES stuff, here's what I'd advise you.

Go down to your local radio parts store, Rat Shack if that's all you've
got
and get yourself a female BNC chassis connector (UG-1094, RS # 278-105).
Get a couple of quality male BNC cable connectors while you are at it.
Unfortunately for you, RS doesn't sell anything but that twist-on
solderless
crap for male BNC, so you may wind up buying them mail order.

Get yourself four 3/8" solder lugs and five 19" pieces of solid #14
copper
wire (strip house romex if you have to).

To each of the four solder lugs, solder one end of the #14 wire. These
will
be the four ground plane wires. THe fifth piece of #14 will connect to
the
solder cup on the bottom of the female BNC chassis connector to become
the
radiating element.

Now put those four solder lugs over the radiating element and over the
threads on the connector. Use the nut that came with the connector to
fasten the solder lugs, each at approximately 90° from each other (a
small
crescent wrench or dedicated 1/2" wrench needs to be part of your
permanent
tool kit). Bend them down at about a 45° angle.

Take the two male connectors and make an RG-58 cable to run from your
radio
to where you want to put your antenna. Connect one end of the cable to
your
radio and the other end to the UG-1094 connector.

You want to move the antenna? Disconnect the cable. Grab your wrench
and
pull that nut off. Take off all 4 ground plane wires. Bundle them up
around the radiating element. Reassemble in the new location. Ten
seconds
up, ten seconds down.

You want to use it in the field outside? Bend a small hook (no more than
1/4" long) in the radiating element. Tie a roll of heavy twine to the
hook
and bend the hook shut. Take the roll of twine and throw it around the
highest tree limb you can find. Hoist that sucker up and you are on the
air.

We can dick around with a mounting bracket on the UG-1094 threads if you
want to make a permanent installation out of it.

(By the way, you are operating close enough to the third harmonic of 144
on
440 that the antenna will perform quite well on both frequencies.)

Jim

I agree -- Chuck isn't looking to work big DX so, a complicated antenna is
not needed. Another simple concept is a vertical dipole. Here's an
illustration from "Simple, Low Cost Wire Antennas for Radio Amateurs", by
William I. Orr and Stuart D. Cowan: http://tinyurl.com/yzydbo
The bottom section connects to the shield of the feedline. If made from
tubing, it will act to decouple the outer surface of the shield. If cut
for
144-148MHz (38-39" overall length), it will work at 432-444MHz as well. To
make it portable, use stiff wire (welding rod, etc) for the top half, and
schedule-40 ½" copper tubing for the bottom half. An insulated coupling
can
be fashioned from wood or plastic dowel or plastic pipe. More dowel or
plastic pipe can be used as a carring handle. Like the ground plane, it
can
be suspended from an overhead support. It can also be slipped into/onto a
baseplate if you don't have an overhead support available: nonmetallic
umbrella stand, heavy flower vase, etc. With the exception of the
feedline,
your home improvement box store will have all the parts you need.

Bryan WA7PRC

John Smith wrote:
Bryan wrote:
...


You remind me. I have built those antennas, long ago, in the past for
10M+ bands.

If I remember correctly they were termed "bazooka antennas." I kind of
remember there was a recommended ratio of coax shield dia. to inside
diameter of the sleeve--possibly the ratio of the radiating element
figured into securing a 50/75 ohm match also?

You have any more data on that antenna?

Warmest regards,
JS

Hi John,

I found the image he http://www.alpharubicon.com/elect/vertdipoleniet.htm
and cleaned it up. There're more links to bazooka antennas he
http://www.dxzone.com/catalog/Antennas/Bazooka/ I thought this construction
method: http://www.start.ca/users/ldblake/bazooka.htm was particularly
innovative.

73,
Bryan WA7PRC

Chuck James wrote:
This looks like what i am asking for, but the picture is not very clear.
Any more details anywhere?

Hi Chuck,

I found the image he http://www.alpharubicon.com/elect/vertdipoleniet.htm
and cleaned it up -- not much more info available on that page. It's
basically a dipole turned vertical. With the feedline going thru the bottom
half and connecting at the top of that section, it becomes a "bazooka"
vertical.

There're more links to bazooka antennas he
http://www.dxzone.com/catalog/Antennas/Bazooka/ I thought this construction
method: http://www.start.ca/users/ldblake/bazooka.htm was particularly
innovative. I don't think you'd need to use RG-8 as described -- just about
any 50-ohm feedline would work fine.

73,
Bryan WA7PRC