Re: Topband: Use shunt fed tower
Depends upon the concrete/cement . ( Base fed vertical) Years ago, found after experimenting with out base insulators that there were definite high RF losses. (resistance went through to earth) 73 Bruce-k1fz https://www.qsl.net/k1fz/bognotes.html . On Sun, 16 Sep 2018 20:26:02 -0400, Stan wrote: Hi everybody! A couple thoughts on shunt fed towers... Depending on what you read on the web, concrete/cement might (or might not) be somewhat of a conductor. So, could attaching to concrete around the house be a help as a ground/radial? Thoughts??? Feeding a tower with NO RADIALS. It seems it would be possible to feed a tower about halfway up as a center fed vertical dipole, with no need for radials. In most cases it would be a very short dipole for Top Band, tho. Thoughts??? Sometimes weird ideas pop into my head.. Stan K8LL 10-10# 76801 FP# 3255 Propagation is our master... but sometimes the master is cruel! _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
Hi everybody! A couple thoughts on shunt fed towers... Depending on what you read on the web, concrete/cement might (or might not) be somewhat of a conductor. So, could attaching to concrete around the house be a help as a ground/radial? Thoughts??? Feeding a tower with NO RADIALS. It seems it would be possible to feed a tower about halfway up as a center fed vertical dipole, with no need for radials. In most cases it would be a very short dipole for Top Band, tho. Thoughts??? Sometimes weird ideas pop into my head.. Stan K8LL 10-10# 76801 FP# 3255 Propagation is our master... but sometimes the master is cruel! _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
I think the issue is not whether a vertical needs radials or not. A vertical monopole needs a ground system or a counterpoise. The ground system can be the actual ground or radials, or both, or even the shield of the coax (and your station at the end of it). If you have a good ground and it is connected via a low impedance path, you may not need any radials. (I don't use any at C6AGU, but the antenna stands in salt-water.) But if your ground is poor, you do need radials, or some other effective counterpoise. Every location is different and you should plan accordingly. It is very simple to determine whether your ground system is adequate. Model and measure your antenna. If the model indicates a feed point impedance of 25 Ohms and you measure 50 Ohms, the extra 25 Ohms is probably contributed by the (poor) ground system. (Of course it could be a poor model too.) 73, George, AA7JV On Sun, 16 Sep 2018 10:11:06 -0400 (EDT) kol...@rcn.com wrote: Well, my system here at K3OX is a "T" with a 40 ft vertical section and a 90 ft flat top. It sort of worked OK when I first put it up, but it works much more OK after about 32 random (to fit my 4 0 x 110 lot) radials were installed. It would work better yet if I had more and longer radials, and mo' better than that if the vertical section was 130 ft! So saying an antenna "works" is a relative thing. But the moral is, you do what you can. T o paraphrase Clint Eastwood, "A man's gotta know his antenna limitations". 73 Kevin K3OX - Original Message - From: "Peter Voelpel" To: topband@contesting.com Sent: Sunday, September 16, 2018 9:44:46 AM Subject: Re: Topband: Use shunt fed tower It can work and it does. I used a shunt fed tower without radials for a couple of years on the former qth just with the tower grounding. Now I feed the tower directly and against a single sloping radial, it works great and is also a better receiving antenna then my relatively short beverages. 73 Peter, DJ7WW -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of John Harden, D.M.D. Sent: Sonntag, 16. September 2018 02:43 To: daraym...@iowatelecom.net Cc: topband@contesting.com; cfytech24x7 Subject: Re: Topband: Use shunt fed tower A shunt fed tower requires radials period. It cannot work without them! 73, John, W4NU Sent from my iPhone On Sep 15, 2018, at 1:55 PM, wrote: It makes no difference how the tower is fed, a vertical antenna must have radials of some kind to be effective. 73. . .Dave, W0FLS -Original Message- From: cfytech24x7 Sent: Saturday, September 15, 2018 11:29 AM To: topband@contesting.com Subject: Topband: Use shunt fed tower A shunt fed tower is a vertical antenna so it offers lowest take off angle. Shunt feeding avoids need for radial field. Any horizontal wire antenna is going to put most of your radiated energy out at high angles, unless you can get it at least a half wavelength of height. A loop may be a quieter antenna for RX but your existing inverted Vs are no doubt better for TX. There is some art and experimentation involved in the matching but the results will be worth the effort. I would start with your highest antenna for top band, next highes for 80m. Note that your yagis will act nicely as capacitive hats to add to effective tower hight. Gl es 73, ab1vl chuck Sent from my Galaxy TabR A _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
Well, my system here at K3OX is a "T" with a 40 ft vertical section and a 90 ft flat top. It sort of worked OK when I first put it up, but it works much more OK after about 32 random (to fit my 4 0 x 110 lot) radials were installed. It would work better yet if I had more and longer radials, and mo' better than that if the vertical section was 130 ft! So saying an antenna "works" is a relative thing. But the moral is, you do what you can. T o paraphrase Clint Eastwood, "A man's gotta know his antenna limitations". 73 Kevin K3OX - Original Message - From: "Peter Voelpel" To: topband@contesting.com Sent: Sunday, September 16, 2018 9:44:46 AM Subject: Re: Topband: Use shunt fed tower It can work and it does. I used a shunt fed tower without radials for a couple of years on the former qth just with the tower grounding. Now I feed the tower directly and against a single sloping radial, it works great and is also a better receiving antenna then my relatively short beverages. 73 Peter, DJ7WW -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of John Harden, D.M.D. Sent: Sonntag, 16. September 2018 02:43 To: daraym...@iowatelecom.net Cc: topband@contesting.com; cfytech24x7 Subject: Re: Topband: Use shunt fed tower A shunt fed tower requires radials period. It cannot work without them! 73, John, W4NU Sent from my iPhone > On Sep 15, 2018, at 1:55 PM, wrote: > > It makes no difference how the tower is fed, a vertical antenna must have radials of some kind to be effective. 73. . .Dave, W0FLS > > -Original Message- From: cfytech24x7 > Sent: Saturday, September 15, 2018 11:29 AM > To: topband@contesting.com > Subject: Topband: Use shunt fed tower > > A shunt fed tower is a vertical antenna so it offers lowest take off angle. Shunt feeding avoids need for radial field. Any horizontal wire antenna is going to put most of your radiated energy out at high angles, unless you can get it at least a half wavelength of height. A loop may be a quieter antenna for RX but your existing inverted Vs are no doubt better for TX. > There is some art and experimentation involved in the matching but the results will be worth the effort. I would start with your highest antenna for top band, next highes for 80m. Note that your yagis will act nicely as capacitive hats to add to effective tower hight. > Gl es 73, ab1vl chuck > > > > > Sent from my Galaxy TabR A > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ > Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
It can work and it does. I used a shunt fed tower without radials for a couple of years on the former qth just with the tower grounding. Now I feed the tower directly and against a single sloping radial, it works great and is also a better receiving antenna then my relatively short beverages. 73 Peter, DJ7WW -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of John Harden, D.M.D. Sent: Sonntag, 16. September 2018 02:43 To: daraym...@iowatelecom.net Cc: topband@contesting.com; cfytech24x7 Subject: Re: Topband: Use shunt fed tower A shunt fed tower requires radials period. It cannot work without them! 73, John, W4NU Sent from my iPhone > On Sep 15, 2018, at 1:55 PM, wrote: > > It makes no difference how the tower is fed, a vertical antenna must have radials of some kind to be effective. 73. . .Dave, W0FLS > > -Original Message- From: cfytech24x7 > Sent: Saturday, September 15, 2018 11:29 AM > To: topband@contesting.com > Subject: Topband: Use shunt fed tower > > A shunt fed tower is a vertical antenna so it offers lowest take off angle. Shunt feeding avoids need for radial field. Any horizontal wire antenna is going to put most of your radiated energy out at high angles, unless you can get it at least a half wavelength of height. A loop may be a quieter antenna for RX but your existing inverted Vs are no doubt better for TX. > There is some art and experimentation involved in the matching but the results will be worth the effort. I would start with your highest antenna for top band, next highes for 80m. Note that your yagis will act nicely as capacitive hats to add to effective tower hight. > Gl es 73, ab1vl chuck > > > > > Sent from my Galaxy TabR A > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ > Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
Steve, Think you are doing a great job considering the lot size.Never know what else is in the mix. The power line neutral (ground) may. be helping Someone years ago fastened to a metal sewer line. 73 Bruce-k1fz https://www.qsl.net/k1fz/beverage_antenna.html On Sat, 15 Sep 2018 19:36:13 -0700, Steve Lawrence via Topband wrote: 217 DXCC 36 Zones. Shunt fed tower. No radials. West Coast city lot. I can only imagine my totals if it really worked. 73 Steve WB6RSE > On Sep 15, 2018, at 5:42 PM, John Harden, D.M.D. wrote: > > A shunt fed tower requires radials period. It cannot work without them! > > 73, > > John, W4NU > > Sent from my iPhone > >> On Sep 15, 2018, at 1:55 PM, wrote: >> >> It makes no difference how the tower is fed, a vertical antenna must have >> radials of some kind to be effective. 73. . .Dave, W0FLS >> >> -Original Message- From: cfytech24x7 >> Sent: Saturday, September 15, 2018 11:29 AM >> To: topband@contesting.com >> Subject: Topband: Use shunt fed tower >> >> A shunt fed tower is a vertical antenna so it offers lowest take off angle. >> Shunt feeding avoids need for radial field. Any horizontal wire antenna is >> going to put most of your radiated energy out at high angles, unless you can >> get it at least a half wavelength of height. A loop may be a quieter >> antenna for RX but your existing inverted Vs are no doubt better for TX. >> There is some art and experimentation involved in the matching but the >> results will be worth the effort. I would start with your highest antenna >> for top band, next highes for 80m. Note that your yagis will act nicely as >> capacitive hats to add to effective tower hight. >> Gl es 73, ab1vl chuck >> >> >> >> >> Sent from my Galaxy Tab® A >> _ >> Topband Reflector Archives - http://www.contesting.com/_topband >> _ >> Topband Reflector Archives - http://www.contesting.com/_topband > > _ > Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
Any antenna can work. . . it's a question of degree. -Original Message- From: Steve Lawrence Sent: Saturday, September 15, 2018 9:36 PM To: John Harden, D.M.D. Cc: daraym...@iowatelecom.net ; topband@contesting.com ; cfytech24x7 Subject: Re: Topband: Use shunt fed tower 217 DXCC 36 Zones. Shunt fed tower. No radials. West Coast city lot. I can only imagine my totals if it really worked. 73 Steve WB6RSE On Sep 15, 2018, at 5:42 PM, John Harden, D.M.D. wrote: A shunt fed tower requires radials period. It cannot work without them! 73, John, W4NU Sent from my iPhone On Sep 15, 2018, at 1:55 PM, wrote: It makes no difference how the tower is fed, a vertical antenna must have radials of some kind to be effective. 73. . .Dave, W0FLS -Original Message- From: cfytech24x7 Sent: Saturday, September 15, 2018 11:29 AM To: topband@contesting.com Subject: Topband: Use shunt fed tower A shunt fed tower is a vertical antenna so it offers lowest take off angle. Shunt feeding avoids need for radial field. Any horizontal wire antenna is going to put most of your radiated energy out at high angles, unless you can get it at least a half wavelength of height. A loop may be a quieter antenna for RX but your existing inverted Vs are no doubt better for TX. There is some art and experimentation involved in the matching but the results will be worth the effort. I would start with your highest antenna for top band, next highes for 80m. Note that your yagis will act nicely as capacitive hats to add to effective tower hight. Gl es 73, ab1vl chuck Sent from my Galaxy Tab® A _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
217 DXCC 36 Zones. Shunt fed tower. No radials. West Coast city lot. I can only imagine my totals if it really worked. 73 Steve WB6RSE > On Sep 15, 2018, at 5:42 PM, John Harden, D.M.D. wrote: > > A shunt fed tower requires radials period. It cannot work without them! > > 73, > > John, W4NU > > Sent from my iPhone > >> On Sep 15, 2018, at 1:55 PM, >> wrote: >> >> It makes no difference how the tower is fed, a vertical antenna must have >> radials of some kind to be effective. 73. . .Dave, W0FLS >> >> -Original Message- From: cfytech24x7 >> Sent: Saturday, September 15, 2018 11:29 AM >> To: topband@contesting.com >> Subject: Topband: Use shunt fed tower >> >> A shunt fed tower is a vertical antenna so it offers lowest take off angle. >> Shunt feeding avoids need for radial field. Any horizontal wire antenna is >> going to put most of your radiated energy out at high angles, unless you can >> get it at least a half wavelength of height. A loop may be a quieter >> antenna for RX but your existing inverted Vs are no doubt better for TX. >> There is some art and experimentation involved in the matching but the >> results will be worth the effort. I would start with your highest antenna >> for top band, next highes for 80m. Note that your yagis will act nicely as >> capacitive hats to add to effective tower hight. >> Gl es 73, ab1vl chuck >> >> >> >> >> Sent from my Galaxy Tab® A >> _ >> Topband Reflector Archives - http://www.contesting.com/_topband >> _ >> Topband Reflector Archives - http://www.contesting.com/_topband > > _ > Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
A shunt fed tower requires radials period. It cannot work without them! 73, John, W4NU Sent from my iPhone > On Sep 15, 2018, at 1:55 PM, > wrote: > > It makes no difference how the tower is fed, a vertical antenna must have > radials of some kind to be effective. 73. . .Dave, W0FLS > > -Original Message- From: cfytech24x7 > Sent: Saturday, September 15, 2018 11:29 AM > To: topband@contesting.com > Subject: Topband: Use shunt fed tower > > A shunt fed tower is a vertical antenna so it offers lowest take off angle. > Shunt feeding avoids need for radial field. Any horizontal wire antenna is > going to put most of your radiated energy out at high angles, unless you can > get it at least a half wavelength of height. A loop may be a quieter antenna > for RX but your existing inverted Vs are no doubt better for TX. > There is some art and experimentation involved in the matching but the > results will be worth the effort. I would start with your highest antenna > for top band, next highes for 80m. Note that your yagis will act nicely as > capacitive hats to add to effective tower hight. > Gl es 73, ab1vl chuck > > > > > Sent from my Galaxy Tab® A > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ > Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
Hi Mike - Yes no doubt that radials, any radials, would at the least not hurt.
My house is literally surrounded by concrete and brick. IE no digging to plant
radials. I did try a couple of full length radials attached at the tower and
snaked around the perimeter of the house for part of a season. I could not note
any difference so I took them up. My ground system at the shack is another 8 ft
copper rod driven into the ground and attached to the gear and the copper water
pipe system for the house.
QRO not doubt serves to help compensate for whatever poor TX efficiency I have.
The thing a quickly discovered was that I could be heard but I couldn't always
hear. That sent me on the search for a decent RX antenna for a small city lot.
But I am fast approaching an asymptote in terms of what's workable from this
QTH on Top Band.
Again my point was that in my case the no radial shunt feed works and is worth
a try. If you can lay down radials, all the better. A description of my shunt
fed appeared in Feb 2013 QST.
The original plan was to confirm 100 on Top Band and having accomplished that
from a small West Coast city lot, declare victory and not concern myself with
160 anymore. Who was I kidding?
73 - Steve WB6RSE
> On Sep 15, 2018, at 2:53 PM, Mike Waters wrote:
>
> Hi Steve,
>
> It sounds like you have done *much* better on 160 than I --and a lot of
> other Topbanders-- have, *and from such a small lot*! It sounds like you
> have exceptionally good ground conductivity.
>
> In any case, I believe that you would have done even better (is that
> possible? ;-) if you had laid down as many short radials on your small lot
> as is possible and connected those to your ground rods.
> I recall W8JI once telling me that there was another Topbander not far from
> his first QTH in NW Ohio. The other ham had an inverted-L thrown over a
> tree on his very small city lot, and he laid down many radials --short as
> they were-- anyplace that he could fit them in. I think he even had some of
> them running under or through his house.
> Now, Tom had a 120' tower with 120 λ/4 radials connected to it, and they
> used to compare signals ("RF drag race", I guess) on 160m. As unbelievable
> as it may seem to some, the other ham was doing almost as well as Tom.
>
> I'm just sharing what I believe to be true for the benefit of present and
> future readers of this thread. What is your opinion?
>
> 73, Mike
> www.w0btu.com
>
> On Sat, Sep 15, 2018 at 3:21 PM Steve Lawrence via Topband <
> topband@contesting.com> wrote:
>
>> My shunt fed tower has no radials. Two 8 ft copper ground rods were driven
>> into the soil when the tower base was installed. Heavy gauge wire was used
>> to attach the rods to the tower base bolts. There is simply no place for
>> any radials on my postage stamp size West Coast city lot.
>>
>> I believe my house plot was part of a golf course which flooded when it
>> rained. Flood control channels were built just before the housing tract was
>> developed.
>>
>> I use the shunt feed on 160 and 80m where I have over 200 DXCC confirmed
>> on Top Band and into the high 200s on 80.
>>
>> Obviously I've been fortunate relative to ground conditions. The laws of
>> physics are still at work. Could the performance improve with radials? It's
>> just not possible at this QTH.
>>
>> My point: Even if you can't install radials you could do worse that not
>> even try a shunt feed to see how it works. It's not a particularly
>> difficult nor expensive proposition.
>>
>> Your mileage will vary.
>>
>> GL - Steve WB6RSE
>>
_
Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
Hi Steve,
It sounds like you have done *much* better on 160 than I --and a lot of
other Topbanders-- have, *and from such a small lot*! It sounds like you
have exceptionally good ground conductivity.
In any case, I believe that you would have done even better (is that
possible? ;-) if you had laid down as many short radials on your small lot
as is possible and connected those to your ground rods.
I recall W8JI once telling me that there was another Topbander not far from
his first QTH in NW Ohio. The other ham had an inverted-L thrown over a
tree on his very small city lot, and he laid down many radials --short as
they were-- anyplace that he could fit them in. I think he even had some of
them running under or through his house.
Now, Tom had a 120' tower with 120 λ/4 radials connected to it, and they
used to compare signals ("RF drag race", I guess) on 160m. As unbelievable
as it may seem to some, the other ham was doing almost as well as Tom.
I'm just sharing what I believe to be true for the benefit of present and
future readers of this thread. What is your opinion?
73, Mike
www.w0btu.com
On Sat, Sep 15, 2018 at 3:21 PM Steve Lawrence via Topband <
topband@contesting.com> wrote:
> My shunt fed tower has no radials. Two 8 ft copper ground rods were driven
> into the soil when the tower base was installed. Heavy gauge wire was used
> to attach the rods to the tower base bolts. There is simply no place for
> any radials on my postage stamp size West Coast city lot.
>
> I believe my house plot was part of a golf course which flooded when it
> rained. Flood control channels were built just before the housing tract was
> developed.
>
> I use the shunt feed on 160 and 80m where I have over 200 DXCC confirmed
> on Top Band and into the high 200s on 80.
>
> Obviously I've been fortunate relative to ground conditions. The laws of
> physics are still at work. Could the performance improve with radials? It's
> just not possible at this QTH.
>
> My point: Even if you can't install radials you could do worse that not
> even try a shunt feed to see how it works. It's not a particularly
> difficult nor expensive proposition.
>
> Your mileage will vary.
>
> GL - Steve WB6RSE
>
_
Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
Hi Guys, here my two cents. Radials are important to increase the power gain. The directivity gain is the same. More efficiency means more irradiated power, just it. Steve TX antenna may have 50 % efficiency. It means using a 1 Kw only 500w is irradiated. The ground type is responsible for low angle irradiation on the far field. My back yard is quite small, 100 x 150 ft. and my tower is not in the center because I need to tilt it over. There are 64 radials, most of them only 50 ft. long. The efficiency may be 80% or a little better. No problems to work #298 countries on 160m using a pair of 3CX800 legal limit power amplifier. 1K5 in and 1k2 out (80%). Doug NX4D city lot is 1/5 of acre, no space for radials. Most of them are 20 ft. long. Doug worked #311 on 160m. For sure more radials is always good, but increase the efficiency for 90% to 95% is only 5% increase, and it means you double the number of radials. The more important thing most top-bands like to ignore is the re-radiation of noise. It is very simple to eliminate it and tune your tower. The best way is 3 or more wires 1ft around the tower , grounded at the top of the tower and connected together at the bottom. This is called UNIPOLE, or Folded Unipole, the impedance is near 200 ohm, just a 1200pf and a 4:1 BALUN can give you over 200 KHz of bandwidth. Very broad band. If your tower is over 100ft you can get 200KHz below 1.5 SWR. The second advantage besides the broadband is to detune the tower. If the skirt is less than 36m, you can add a capacitor to ground and tune for 1.8 MHz If you use only one wire to shunt feed the tower, you can do the same. If you use an inverted L you can the same as well, just disconnect the wire from the cable. A vacuum relay is a must because the speed, you need 10 ms or less to avoid hot switch during TX. Detuning your TX antenna the way above can save you several S units of noise on any RX antenna. I've seen cases of 4 S units decrease in urban areas, 2 S units or more is the average for most stations. Using multiple tower it is very important to detune all of them. You can phase all of them as well to increase gain and directivity. Vertical arrays around the tower can perform very well if you detune the tower at the center of the array. Any EWE, FLAG, K9AY, Hi-z verticals and HWF or VWF will perform better if you detune your TX antenna. Most of them wont perform if you do not detune your tower. No pain no gain! 73's JC N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Steve Lawrence via Topband Sent: Saturday, September 15, 2018 3:22 PM To: Top Band List List Subject: Re: Topband: Use shunt fed tower My shunt fed tower has no radials. Two 8 ft copper ground rods were driven into the soil when the tower base was installed. Heavy gauge wire was used to attach the rods to the tower base bolts. There is simply no place for any radials on my postage stamp size West Coast city lot. I believe my house plot was part of a golf course which flooded when it rained. Flood control channels were built just before the housing tract was developed. I use the shunt feed on 160 and 80m where I have over 200 DXCC confirmed on Top Band and into the high 200s on 80. Obviously I've been fortunate relative to ground conditions. The laws of physics are still at work. Could the performance improve with radials? It's just not possible at this QTH. My point: Even if you can't install radials you could do worse that not even try a shunt feed to see how it works. It's not a particularly difficult nor expensive proposition. Your mileage will vary. GL - Steve WB6RSE _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
My shunt fed tower has no radials. Two 8 ft copper ground rods were driven into the soil when the tower base was installed. Heavy gauge wire was used to attach the rods to the tower base bolts. There is simply no place for any radials on my postage stamp size West Coast city lot. I believe my house plot was part of a golf course which flooded when it rained. Flood control channels were built just before the housing tract was developed. I use the shunt feed on 160 and 80m where I have over 200 DXCC confirmed on Top Band and into the high 200s on 80. Obviously I've been fortunate relative to ground conditions. The laws of physics are still at work. Could the performance improve with radials? It's just not possible at this QTH. My point: Even if you can't install radials you could do worse that not even try a shunt feed to see how it works. It's not a particularly difficult nor expensive proposition. Your mileage will vary. GL - Steve WB6RSE _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Use shunt fed tower
Chuck, I would disagree with you that tower shunt feeding avoids needing radials. Any vertical antenna without some kind of counterpoise will be disadvantaged unless it is close to 1/2 wavelength long. Even then some sort of radials are best. A shunt fed tower does indeed need a good radial field for the best efficiency. Lee K7TJR OR A shunt fed tower is a vertical antenna so it offers lowest take off angle. Shunt feeding avoids need for radial field. Any horizontal wire antenna is going to put most of your radiated energy out at high angles, unless you can get it at least a half wavelength of height. A loop may be a quieter antenna for RX but your existing inverted Vs are no doubt better for TX. There is some art and experimentation involved in the matching but the results will be worth the effort. I would start with your highest antenna for top band, next highes for 80m. Note that your yagis will act nicely as capacitive hats to add to effective tower hight. Gl es 73, ab1vl chuck Sent from my Galaxy Tab® A _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
It makes no difference how the tower is fed, a vertical antenna must have radials of some kind to be effective. 73. . .Dave, W0FLS -Original Message- From: cfytech24x7 Sent: Saturday, September 15, 2018 11:29 AM To: topband@contesting.com Subject: Topband: Use shunt fed tower A shunt fed tower is a vertical antenna so it offers lowest take off angle. Shunt feeding avoids need for radial field. Any horizontal wire antenna is going to put most of your radiated energy out at high angles, unless you can get it at least a half wavelength of height. A loop may be a quieter antenna for RX but your existing inverted Vs are no doubt better for TX. There is some art and experimentation involved in the matching but the results will be worth the effort. I would start with your highest antenna for top band, next highes for 80m. Note that your yagis will act nicely as capacitive hats to add to effective tower hight. Gl es 73, ab1vl chuck Sent from my Galaxy Tab® A _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Use shunt fed tower
Hello Chuck, On Sat, Sep 15, 2018, 11:30 AM cfytech24x7 wrote: > A shunt fed tower is a vertical antenna so it offers lowest take off > angle. True. 160m is a band for vertical polarization if we want to work DX. See www.w0btu.com/160_meters.html . Shunt feeding avoids need for radial field. Sorry, that's just not true. A verical needs an RF ground, something to "push against". Scroll down this page to see why. w0btu.com/Optimum_number_of_ground_radials_vs_radial_length.html But the following is certainly true! :-) > Any horizontal wire antenna is going to put most of your radiated energy > out at high angles, unless you can get it at least a half wavelength of > height. A loop may be a quieter antenna for RX but your existing inverted > Vs are no doubt better for TX. > There is some art and experimentation involved in the matching but the > results will be worth the effort. I would start with your highest antenna > for top band, next highes for 80m. Note that your yagis will act nicely as > capacitive hats to add to effective tower hight. > Gl es 73, ab1vl chuck > 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Use shunt fed tower
A shunt fed tower is a vertical antenna so it offers lowest take off angle. Shunt feeding avoids need for radial field. Any horizontal wire antenna is going to put most of your radiated energy out at high angles, unless you can get it at least a half wavelength of height. A loop may be a quieter antenna for RX but your existing inverted Vs are no doubt better for TX. There is some art and experimentation involved in the matching but the results will be worth the effort. I would start with your highest antenna for top band, next highes for 80m. Note that your yagis will act nicely as capacitive hats to add to effective tower hight. Gl es 73, ab1vl chuck Sent from my Galaxy Tab® A _ Topband Reflector Archives - http://www.contesting.com/_topband
