I am looking for recommendations for a dual band antenna that will serve two separate radios. The reason that I want to use a single antenna is that I have a limited number of mounting points for antennas. At present it will be hard for SWMBO; as in Rumpole's spouse, She Who Must Be Obeyed; to tolerate the use of both our home's gable ends and the chimney being used to support antennas. I am planning to replace my Diamond X-30 with a triband vertical for Six, Two, and .7 Meters. The chimney will then support a rotor aimed Two and .7 Meter beam. The second gable end will support the Two meter / Seventy Centimeter dual band vertical that I am asking for help in selecting.

One radio will be a two meter packet node which will be used as a Winlink Radio Message Server. The other radio will be a UHF D-STAR hotspot. I am willing to pay what is needed to to get the best antenna for this application but I don't want to waste money ineffectively. So the two meter radio will be in the 144 MHz portion of the band and I don't yet actually know were the D-STAR hotspot will be run. I have a DCI filter and diplexer to keep the two radios from actually knowing of each others existence. Since a hotspot is not supposed to be a terribly wide area installation I would imagine that I do not want an extremely high gain antenna but I am perfectly open to be reeducated on that. The difficulty is that I would guess that the Radio Message Server / Packet would benefit from as much horizontal gain as can be achieved. I have a home brewed collinear two meter J-Pole that has been a good performer on two meters and presents a low SWR on 440 MHz. I have yet to master antenna modeling but I would imagine; given all the warnings I have read on line; that it has poor radiation pattern on UHF. Is it likely to be too poor a performer for a hot spot on UHF?

I really am asking because I want to know. I am not looking for encouragement to do something that will be ineffective. Thank you in advance for any help you may be willing to offer.

--
Tom Horne W3TDH

On 3/11/2015 6:02 PM, Tom W3TDH wrote:
I am looking for recommendations for a dual band antenna that will serve two separate radios. The reason that I want to use a single antenna is that I have a limited number of mounting points for antennas. At present it will be hard for SWMBO; as in Rumpole's spouse, She Who Must Be Obeyed; to tolerate the use of both our home's gable ends and the chimney being used to support antennas. I am planning to replace my Diamond X-30 with a triband vertical for Six, Two, and .7 Meters. The chimney will then support a rotor aimed Two and .7 Meter beam. The second gable end will support the Two meter / Seventy Centimeter dual band vertical that I am asking for help in selecting.

One radio will be a two meter packet node which will be used as a Winlink Radio Message Server. The other radio will be a UHF D-STAR hotspot. I am willing to pay what is needed to to get the best antenna for this application but I don't want to waste money ineffectively. So the two meter radio will be in the 144 MHz portion of the band and I don't yet actually know were the D-STAR hotspot will be run. I have a DCI filter and diplexer to keep the two radios from actually knowing of each others existence. Since a hotspot is not supposed to be a terribly wide area installation I would imagine that I do not want an extremely high gain antenna but I am perfectly open to be reeducated on that. The difficulty is that I would guess that the Radio Message Server / Packet would benefit from as much horizontal gain as can be achieved. I have a home brewed collinear two meter J-Pole that has been a good performer on two meters and presents a low SWR on 440 MHz. I have yet to master an
tenna modeling but I would imagine; given all the warnings I have read on line; that it has poor radiation pattern on UHF. Is it likely to be too poor a performer for a hot spot on UHF?

I really am asking because I want to know. I am not looking for encouragement to do something that will be ineffective. Thank you in advance for any help you may be willing to offer.

--
Tom Horne W3TDH


Tom,

There are a number of good antennas around. The problem is not going to
be the antenna, though - it will be separating the two radios. If you
transmit on one while both are connected to the antenna, you'll blow the
front end of the other.

You'll need either a coax switch/relay or some kind of filters to ensure
one does not get into the other. And even though we're talking VHF and
UHF, good filers which will provide the separation you need yet not
degrade the signal you want are expensive. If you're only talking one
frequency, maybe a couple of sets of duplexers will work - one set for
each band.

Of course, rf detecting coax switches will work - but you also then need
to ensure that both don't try to transmit at the same time - one or both
will be transmitting into an open circuit (depending on how you wire
them up).

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

On Wednesday, March 11, 2015 at 8:15:54 PM UTC-4, Jerry Stuckle wrote:
On 3/11/2015 6:02 PM, Tom W3TDH wrote:
I am looking for recommendations for a dual band antenna that will serve two separate radios. The reason that I want to use a single antenna is that I have a limited number of mounting points for antennas. At present it will be hard for SWMBO; as in Rumpole's spouse, She Who Must Be Obeyed; to tolerate the use of both our home's gable ends and the chimney being used to support antennas. I am planning to replace my Diamond X-30 with a triband vertical for Six, Two, and .7 Meters. The chimney will then support a rotor aimed Two and .7 Meter beam. The second gable end will support the Two meter / Seventy Centimeter dual band vertical that I am asking for help in selecting.

One radio will be a two meter packet node which will be used as a Winlink Radio Message Server. The other radio will be a UHF D-STAR hotspot. I am willing to pay what is needed to to get the best antenna for this application but I don't want to waste money ineffectively. So the two meter radio will be in the 144 MHz portion of the band and I don't yet actually know were the D-STAR hotspot will be run. I have a DCI filter and diplexer to keep the two radios from actually knowing of each others existence. Since a hotspot is not supposed to be a terribly wide area installation I would imagine that I do not want an extremely high gain antenna but I am perfectly open to be reeducated on that. The difficulty is that I would guess that the Radio Message Server / Packet would benefit from as much horizontal gain as can be achieved. I have a home brewed collinear two meter J-Pole that has been a good performer on two meters and presents a low SWR on 440 MHz. I have yet to master an
tenna modeling but I would imagine; given all the warnings I have read on line; that it has poor radiation pattern on UHF. Is it likely to be too poor a performer for a hot spot on UHF?

I really am asking because I want to know. I am not looking for encouragement to do something that will be ineffective. Thank you in advance for any help you may be willing to offer.

--
Tom Horne W3TDH


Tom,

There are a number of good antennas around. The problem is not going to
be the antenna, though - it will be separating the two radios. If you
transmit on one while both are connected to the antenna, you'll blow the
front end of the other.

You'll need either a coax switch/relay or some kind of filters to ensure
one does not get into the other. And even though we're talking VHF and
UHF, good filers which will provide the separation you need yet not
degrade the signal you want are expensive. If you're only talking one
frequency, maybe a couple of sets of duplexers will work - one set for
each band.

Of course, rf detecting coax switches will work - but you also then need
to ensure that both don't try to transmit at the same time - one or both
will be transmitting into an open circuit (depending on how you wire
them up).

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

Jerry

I am going to declare myself lost on this one so please be patient. I had though I had addressed these issues when I said I was using a DCI Dual Band Filter and Diplexer. Is the DCI combination filter and diplexer insufficient to protect the two radios from each other? DCI claimed it would be. The model number is DCI-146-444-DX-DB. The web sight were it is listed is
http://www.dci.ca/?Section=Products&SubSection=Amateur. If I need to add Duplexers it is practical to do because the mobile ones available used are manageable money. If there is a real chance for damage in the event of simultaneous transmission then I will need to add circulators and dummy loads to the output of both radios. That will end up being a little pricy.

--
Tom Horne W3TDH

"Tom W3TDH" wrote in message
...
I am going to declare myself lost on this one so please be patient. I had
though I had addressed these issues when I said I was using a DCI Dual
Band Filter and Diplexer. Is the DCI combination filter and diplexer
insufficient to protect the two radios from each other? DCI claimed it
would be. The model number is DCI-146-444-DX-DB. The web sight were it
is listed is
http://www.dci.ca/?Section=Products&SubSection=Amateur. If I need to add
Duplexers it is practical to do because the mobile ones available used are
manageable money. If there is a real chance for damage in the event .of
simultaneous transmission then I will need to add circulators and dummy
loads to the output of both radios. That will end up being a little
pricy.


That DCI should be plenty to protect the two rigs. You may have a desense
on the 440 receiver if it on a near 3 rd harmonic of the 144 transmiter. It
won't be enough to cause any damage, just enough to block the 440 receiver.

In article ,
"Ralph Mowery" wrote:

"Tom W3TDH" wrote in message
...
I am going to declare myself lost on this one so please be patient. I had
though I had addressed these issues when I said I was using a DCI Dual
Band Filter and Diplexer. Is the DCI combination filter and diplexer
insufficient to protect the two radios from each other? DCI claimed it
would be. The model number is DCI-146-444-DX-DB. The web sight were it
is listed is
http://www.dci.ca/?Section=Products&SubSection=Amateur. If I need to add
Duplexers it is practical to do because the mobile ones available used are
manageable money. If there is a real chance for damage in the event .of
simultaneous transmission then I will need to add circulators and dummy
loads to the output of both radios. That will end up being a little
pricy.


That DCI should be plenty to protect the two rigs. You may have a desense
on the 440 receiver if it on a near 3 rd harmonic of the 144 transmiter. It
won't be enough to cause any damage, just enough to block the 440 receiver.

I agree that you are not likely to damage a radio. The common duplexer
(or triplexer) is often used to connect a single multi-band antenna to
multiple connectors of a multi-band radio, which is essentially multiple
radios in a single package. The difference between this and what you
are planning, is that the multi-band radio is usually not used for
simultaneous reception and transmission. Or at least you would accept
some desensitization if it occurred.

You can choose frequencies such that the third harmonic of the Two Meter
frequency is not in the IF passband of the 440 receiver, but you are
likely have overloading of the receiver's broad front end. (You may
also have some overloading of the Two Meter radio due to the amount of
power involved.)

That said, go ahead and try it. It may work well enough to meet your
needs. If it does not work out, the alternative is a "real" repeater.

One advantage of a repeater, is that local users can hear each other.
With your Hot Spot, local users are talking simplex.

73,
Fred
K4DII

Fred McKenzie wrote:
I agree that you are not likely to damage a radio. The common duplexer
(or triplexer) is often used to connect a single multi-band antenna to
multiple connectors of a multi-band radio, which is essentially multiple
radios in a single package. The difference between this and what you
are planning, is that the multi-band radio is usually not used for
simultaneous reception and transmission. Or at least you would accept
some desensitization if it occurred.

You can choose frequencies such that the third harmonic of the Two Meter
frequency is not in the IF passband of the 440 receiver, but you are
likely have overloading of the receiver's broad front end. (You may
also have some overloading of the Two Meter radio due to the amount of
power involved.)

I have heard this "armchair theorist" story many times, but I have
never experienced this problem with my 3-band Diamond and matching
triplexer. Sure I hear the harmonics full-scale when tuned that way,
but never any overloading let alone damage.

Maybe it is only a problem when using QRO.


I think it is more warranted to warn against collinear antennas that get
shipped in two parts. The connection is the weak point in the antenna.
Unfortunately it appears that for a 6/2/70 tribander it is the only
option. Normally they fail within a couple of years. Also on the high
bands there is severe fading in windy conditions because the entire
antenna bends too much.

My 2/70/23 tribander is in one piece and it does not have those defects.

On Thursday, March 12, 2015 at 11:41:23 PM UTC-4, Fred McKenzie wrote:
In article ,
"Ralph Mowery" wrote:

"Tom W3TDH" wrote in message
...
I am going to declare myself lost on this one so please be patient. I had
though I had addressed these issues when I said I was using a DCI Dual
Band Filter and Diplexer. Is the DCI combination filter and diplexer
insufficient to protect the two radios from each other? DCI claimed it
would be. The model number is DCI-146-444-DX-DB. The web sight were it
is listed is
http://www.dci.ca/?Section=Products&SubSection=Amateur. If I need to add
Duplexers it is practical to do because the mobile ones available used are
manageable money. If there is a real chance for damage in the event ..of
simultaneous transmission then I will need to add circulators and dummy
loads to the output of both radios. That will end up being a little
pricy.


That DCI should be plenty to protect the two rigs. You may have a desense
on the 440 receiver if it on a near 3 rd harmonic of the 144 transmiter.. It
won't be enough to cause any damage, just enough to block the 440 receiver.

I agree that you are not likely to damage a radio. The common duplexer
(or triplexer) is often used to connect a single multi-band antenna to
multiple connectors of a multi-band radio, which is essentially multiple
radios in a single package. The difference between this and what you
are planning, is that the multi-band radio is usually not used for
simultaneous reception and transmission. Or at least you would accept
some desensitization if it occurred.

You can choose frequencies such that the third harmonic of the Two Meter
frequency is not in the IF passband of the 440 receiver, but you are
likely have overloading of the receiver's broad front end. (You may
also have some overloading of the Two Meter radio due to the amount of
power involved.)

That said, go ahead and try it. It may work well enough to meet your
needs. If it does not work out, the alternative is a "real" repeater.

One advantage of a repeater, is that local users can hear each other.
With your Hot Spot, local users are talking simplex.

73,
Fred
K4DII

Fred

As I already said I am not totally conversant with D-STAR. I was under the impression that the persons participating in any given QSO could hear each other over the access point they were using. I had pictured it as somewhat akin to the remote receivers on our club's analog FM repeater in that the other users on the QSO would hear the conversation over the repeaters output. Our D-STAR repeater is located in Germantown and I do not actually know what it's effective range is. We operate six different sites with four repeaters, four remote receivers with radio links back to the analog two meter repeater, and two APRS digipeaters. In addition to those sites we will have several members hosting D-STAR hot spots in order to fill in the edges of our service area that are outside the effective receive range of portable radios. Those using mobile or base station radio will, hopefully, be able to raise the repeater without resorting to one of the hot spots We can make changes to the location of the various elements of our repeater system including the location of the D-STAR repeater itself if that is needed to allow all users to hear the conversation.

On the harmonic de-sensing issue I can purchase a DCI low pass filter that cuts off at 160MHz if that becomes a problem. It would be inserted between the two meter radio and the filter/diplexer so that the harmonic would not reach the diplexer at all. Part of this question affects operations well beyond my home location. The county ARES unit is gearing up to support hospital emergency communications in our area. Our first client hospital purchased an Icom IC-7100 transceiver for the hospital station. If that remains the only transmitter at the hospital's EOC then the use of directly connected multi band antennas will work fine. But if the hospital discovers that it needs more than one mode or frequency to be used at the same time then our team will have to devise a Diplexing setup in order to keep the two radios from clobbering each other. I could see them needing both local tactical voice and medium range digital at the same time in a real disaster situation.

In the Mid Atlantic region the most common natural disaster with region wide effects are severe ice storms. Since I moved to three land in 1980 we have had three such storms that have wiped out communications infrastructure over wide portions of our region. It usually takes at least a week to get all of the wires and fibers back up in the air. Were about fifteen years out from our last bad one so we're about due. The hospitals have learned that continuing to operate when it is very difficult to talk to anyone that is not on campus is more than challenging. That's why I think they are going to want more than one communications pathway available to them and nothing carries long documents as quickly and accurately as digital.

Thanks again for taking the time to help on this.

--
Tom Horne W3TDH

On 3/12/2015 2:06 PM, Tom W3TDH wrote:
On Wednesday, March 11, 2015 at 8:15:54 PM UTC-4, Jerry Stuckle wrote:
On 3/11/2015 6:02 PM, Tom W3TDH wrote:
I am looking for recommendations for a dual band antenna that will serve two separate radios. The reason that I want to use a single antenna is that I have a limited number of mounting points for antennas. At present it will be hard for SWMBO; as in Rumpole's spouse, She Who Must Be Obeyed; to tolerate the use of both our home's gable ends and the chimney being used to support antennas. I am planning to replace my Diamond X-30 with a triband vertical for Six, Two, and .7 Meters. The chimney will then support a rotor aimed Two and .7 Meter beam. The second gable end will support the Two meter / Seventy Centimeter dual band vertical that I am asking for help in selecting.

One radio will be a two meter packet node which will be used as a Winlink Radio Message Server. The other radio will be a UHF D-STAR hotspot. I am willing to pay what is needed to to get the best antenna for this application but I don't want to waste money ineffectively. So the two meter radio will be in the 144 MHz portion of the band and I don't yet actually know were the D-STAR hotspot will be run. I have a DCI filter and diplexer to keep the two radios from actually knowing of each others existence. Since a hotspot is not supposed to be a terribly wide area installation I would imagine that I do not want an extremely high gain antenna but I am perfectly open to be reeducated on that. The difficulty is that I would guess that the Radio Message Server / Packet would benefit from as much horizontal gain as can be achieved. I have a home brewed collinear two meter J-Pole that has been a good performer on two meters and presents a low SWR on 440 MHz. I have yet to master
an
tenna modeling but I would imagine; given all the warnings I have read on line; that it has poor radiation pattern on UHF. Is it likely to be too poor a performer for a hot spot on UHF?

I really am asking because I want to know. I am not looking for encouragement to do something that will be ineffective. Thank you in advance for any help you may be willing to offer.

--
Tom Horne W3TDH


Tom,

There are a number of good antennas around. The problem is not going to
be the antenna, though - it will be separating the two radios. If you
transmit on one while both are connected to the antenna, you'll blow the
front end of the other.

You'll need either a coax switch/relay or some kind of filters to ensure
one does not get into the other. And even though we're talking VHF and
UHF, good filers which will provide the separation you need yet not
degrade the signal you want are expensive. If you're only talking one
frequency, maybe a couple of sets of duplexers will work - one set for
each band.

Of course, rf detecting coax switches will work - but you also then need
to ensure that both don't try to transmit at the same time - one or both
will be transmitting into an open circuit (depending on how you wire
them up).


Jerry

I am going to declare myself lost on this one so please be patient. I had though I had addressed these issues when I said I was using a DCI Dual Band Filter and Diplexer. Is the DCI combination filter and diplexer insufficient to protect the two radios from each other? DCI claimed it would be. The model number is DCI-146-444-DX-DB. The web sight were it is listed is
http://www.dci.ca/?Section=Products&SubSection=Amateur. If I need to add Duplexers it is practical to do because the mobile ones available used are manageable money. If there is a real chance for damage in the event of simultaneous transmission then I will need to add circulators and dummy loads to the output of both radios. That will end up being a little pricy.

--
Tom Horne W3TDH


Tom,

You said you were using a diplexer, but didn't specify which one. Many
of the cheap ones are OK for receive, but can't handle any significant
amount of transmit power. The DCI will handle 200 watts, so unless
you're planning on exceeding that, you should be OK. It's loss
specifications are pretty reasonable, also.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

On 3/11/2015 5:02 PM, Tom W3TDH wrote:
I am looking for recommendations for a dual band antenna that will
serve two separate radios. The reason that I want to use a single
antenna is that I have a limited number of mounting points for
antennas. At present it will be hard for SWMBO; as in Rumpole's
spouse, She Who Must Be Obeyed; to tolerate the use of both our
home's gable ends and the chimney being used to support antennas. I
am planning to replace my Diamond X-30 with a triband vertical for
Six, Two, and .7 Meters. The chimney will then support a rotor aimed
Two and .7 Meter beam. The second gable end will support the Two
meter / Seventy Centimeter dual band vertical that I am asking for
help in selecting.

One radio will be a two meter packet node which will be used as a
Winlink Radio Message Server. The other radio will be a UHF D-STAR
hotspot. I am willing to pay what is needed to to get the best
antenna for this application but I don't want to waste money
ineffectively. So the two meter radio will be in the 144 MHz portion
of the band and I don't yet actually know were the D-STAR hotspot
will be run. I have a DCI filter and diplexer to keep the two radios
from actually knowing of each others existence. Since a hotspot is
not supposed to be a terribly wide area installation I would imagine
that I do not want an extremely high gain antenna but I am perfectly
open to be reeducated on that. The difficulty is that I would guess
that the Radio Message Server / Packet would benefit from as much
horizontal gain as can be achieved. I have a home brewed collinear
two meter J-Pole that has been a good performer on two meters and
presents a low SWR on 440 MHz. I have yet to master antenna modeling
but I would imagine; given all the warnings I have read on line; that
it has poor radiation pattern on UHF. Is it likely to be too poor a
performer for a hot spot on UHF?

I really am asking because I want to know. I am not looking for
encouragement to do something that will be ineffective. Thank you in
advance for any help you may be willing to offer.

-- Tom Horne W3TDH


Hi, Tom -

I did some quick, crude modelling of a vertically-polarized half-wave
(J-Pole) and it seems to have a pattern about as good on 70cm as on 2M.
There is a bit more energy radiated about 50 degrees above the horizon
on 70cm, but there seems to be plenty left at about 1.5 degrees (about
6.5dBi). I assumed an antenna height of 20 feet.

If it were me, I would try the J-Pole. However, you need to consider how
much time and effort it would take to change to a different antenna if
you are not happy.

73, John N1JLS

In article ,
Tom W3TDH wrote:

The other radio will be a UHF D-STAR hotspot.

Tom-

What kind of range are you trying to achieve with the hotspot? The
little antenna that came with a UHF DVAP covers my property fairly well,
just sitting on a table.

I connected it to a Larsen dual-band mag-mounted antenna stuck on top of
a filing cabinet, and get about a half mile range when mobile. The DVAP
puts out about a tenth of a Watt. I suspect it can hear the 50 Watt
mobile a lot further away.

If you want range, consider taking the DVAP with you and connecting to
the internet through a cellular modem or telephone. I'm considering
getting a D-HAP, which holds everything but the radio and the cellular
connection. http://www.portableuniversalpower.com/dhap/

73,
Fred
K4DII