[IRCA] Short antenna radials
I happened to be looking at a Google earth view of the KFI transmitting site (33° 52' 47" N, 118°00' 47" W) which is located smack in the middle of a commercial/industrial area. I was struck by what a small diameter clear area there is around the base of the antenna; maybe 150 feet. Just curious how the resulting short radials could really offer much efficiency? Updates to my understanding of the situation would be welcomed. :-) Bob Coomler Tucson, AZ ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Short antenna radials
I've been recently wondering about this myself (short-radial efficiency, or lack thereof), but more from the standpoint of low-power part 15 transmitting setups. One example I'm thinking of is such that the total length of the antenna AND all ground radials is 3 meters, and does it make much difference if you use a base-fed radiator with radials vs a center-fed segmented short dipole without radials. (The rule in 15.219 specifies the antenna, transmission line, and ground lead cannot exceed 3 meters.) There's other scenarios I'm wondering about, but I'll leave them off as I think it's beyond the scope of this list. As for KFI, I believe the original tower was there long before the industrial complex was built. So, I think there could be ground radials there already, and the new tower was hooked up to them? Or maybe they have another way of grounding it. KFI *is* a few dB weaker at my house than KNX, in spite of being 12 miles closer (99 vs 111). I think it's primarily the partial saltwater path for KNX in my case, though. At a friend's house in Moreno Valley, as well as at my grandma's house in San Gabriel, KFI is considerably stronger, like 10-15 dB. There is a very efficient station that I believe doesn't have ground radials - 1530 KFBK in Sacramento, CA. Also I suspect 1500 KSTP St Paul, MN's daytime site may also not have ground radials, but I'm not totally positive on that one. 73, Stephen -- On Fri, Nov 29, 2013 9:28 AM PST Bob Coomler wrote: > > >I happened to be looking at a Google earth view of the KFI transmitting site >(33° 52' 47" N, 118°00' 47" W) which is located smack in the middle of a >commercial/industrial area. I was struck by what a small diameter clear area >there is around the base of the antenna; maybe 150 feet. Just curious how the >resulting short radials could really offer much efficiency? Updates to my >understanding of the situation would be welcomed. :-) > >Bob Coomler >Tucson, AZ >___ >IRCA mailing list >IRCA@hard-core-dx.com >http://montreal.kotalampi.com/mailman/listinfo/irca > >Opinions expressed in messages on this mailing list are those of the original >contributors and do not necessarily reflect the opinion of the IRCA, its >editors, publishing staff, or officers > >For more information: http://www.ircaonline.org > >To Post a message: irca@hard-core-dx.com > ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Short antenna radials
KFI's original tower was there before the industrial complex was built. The new tower was built at the same place as the old and uses the same ground radials. KFBK and the KSTP day site both use Franklin antennas, the only two in the country. A Franklin antenna consists of two 180 degree electrical height (one half wavelength) antennas separated by an insulator, stacked vertically and fed at the center. The top half radiates and the bottom half is the ground. There are no ground radials. Date: Sat, 30 Nov 2013 13:50:34 -0800 (PST) From: Stephen Airy To: w7...@yahoo.com, irca@hard-core-dx.com Subject: Re: [IRCA] Short antenna radials I've been recently wondering about this myself (short-radial efficiency, or lack thereof), but more from the standpoint of low-power part 15 transmitting setups. One example I'm thinking of is such that the total length of the antenna AND all ground radials is 3 meters, and does it make much difference if you use a base-fed radiator with radials vs a center-fed segmented short dipole without radials. (The rule in 15.219 specifies the antenna, transmission line, and ground lead cannot exceed 3 meters.) There's other scenarios I'm wondering about, but I'll leave them off as I think it's beyond the scope of this list. As for KFI, I believe the original tower was there long before the industrial complex was built. So, I think there could be ground radials there already, and the new tower was hooked up to them? Or maybe they have another way of grounding it. KFI *is* a few dB weaker at my house than KNX, in spite of being 12 miles closer (99 vs 111). I think it's primarily the partial saltwater path for KNX in my case, though. At a friend's house in Moreno Valley, as well as at my grandma's house in San Gabriel, KFI is considerably stronger, like 10-15 dB. There is a very efficient station that I believe doesn't have ground radials - 1530 KFBK in Sacramento, CA. Also I suspect 1500 KSTP St Paul, MN's daytime site may also not have ground radials, but I'm not totally positive on that one. 73, Stephen Sent from my iPad ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Short antenna radials
'Makes me sad that I missed the KFBK tower tour at the 1989 IRCA Conventionms > From: wb6...@yahoo.com > Date: Sat, 30 Nov 2013 20:26:07 -0800 > To: irca@hard-core-dx.com > Subject: Re: [IRCA] Short antenna radials > > KFI's original tower was there before the industrial complex was built. The > new tower was built at the same place as the old and uses the same ground > radials. > > KFBK and the KSTP day site both use Franklin antennas, the only two in the > country. A Franklin antenna consists of two 180 degree electrical height (one > half wavelength) antennas separated by an insulator, stacked vertically and > fed at the center. The top half radiates and the bottom half is the ground. > There are no ground radials. > > Date: Sat, 30 Nov 2013 13:50:34 -0800 (PST) > From: Stephen Airy > To: w7...@yahoo.com, irca@hard-core-dx.com > Subject: Re: [IRCA] Short antenna radials > > I've been recently wondering about this myself (short-radial efficiency, or > lack thereof), but more from the standpoint of low-power part 15 transmitting > setups. One example I'm thinking of is such that the total length of the > antenna AND all ground radials is 3 meters, and does it make much difference > if you use a base-fed radiator with radials vs a center-fed segmented short > dipole without radials. (The rule in 15.219 specifies the antenna, > transmission line, and ground lead cannot exceed 3 meters.) There's other > scenarios I'm wondering about, but I'll leave them off as I think it's beyond > the scope of this list. > > As for KFI, I believe the original tower was there long before the industrial > complex was built. So, I think there could be ground radials there already, > and the new tower was hooked up to them? Or maybe they have another way of > grounding it. KFI *is* a few dB weaker at my house than KNX, in spite of > being 12 miles closer (99 vs 111). I think it's primarily the partial > saltwater path for KNX in my case, though. At a friend's house in Moreno > Valley, as well as at my grandma's house in San Gabriel, KFI is considerably > stronger, like 10-15 dB. > > There is a very efficient station that I believe doesn't have ground radials > - 1530 KFBK in Sacramento, CA. Also I suspect 1500 KSTP St Paul, MN's > daytime site may also not have ground radials, but I'm not totally positive > on that one. > > 73, Stephen > > Sent from my iPad > ___ > IRCA mailing list > IRCA@hard-core-dx.com > http://montreal.kotalampi.com/mailman/listinfo/irca > > Opinions expressed in messages on this mailing list are those of the original > contributors and do not necessarily reflect the opinion of the IRCA, its > editors, publishing staff, or officers > > For more information: http://www.ircaonline.org > > To Post a message: irca@hard-core-dx.com > ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Short antenna radials
To add to Dennis' info: The KSTP antenna was/is a 179.4/179.4 and appears to be considered a "Sectional" rather than a Franklin by the FCC. Nit-picking' I guess. Happy Holidays! Regards, Mark Durenberger -Original Message- From: Dennis Gibson Sent: Saturday, November 30, 2013 10:26 PM To: irca@hard-core-dx.com Subject: Re: [IRCA] Short antenna radials KFI's original tower was there before the industrial complex was built. The new tower was built at the same place as the old and uses the same ground radials. KFBK and the KSTP day site both use Franklin antennas, the only two in the country. A Franklin antenna consists of two 180 degree electrical height (one half wavelength) antennas separated by an insulator, stacked vertically and fed at the center. The top half radiates and the bottom half is the ground. There are no ground radials. Date: Sat, 30 Nov 2013 13:50:34 -0800 (PST) From: Stephen Airy To: w7...@yahoo.com, irca@hard-core-dx.com Subject: Re: [IRCA] Short antenna radials I've been recently wondering about this myself (short-radial efficiency, or lack thereof), but more from the standpoint of low-power part 15 transmitting setups. One example I'm thinking of is such that the total length of the antenna AND all ground radials is 3 meters, and does it make much difference if you use a base-fed radiator with radials vs a center-fed segmented short dipole without radials. (The rule in 15.219 specifies the antenna, transmission line, and ground lead cannot exceed 3 meters.) There's other scenarios I'm wondering about, but I'll leave them off as I think it's beyond the scope of this list. As for KFI, I believe the original tower was there long before the industrial complex was built. So, I think there could be ground radials there already, and the new tower was hooked up to them? Or maybe they have another way of grounding it. KFI *is* a few dB weaker at my house than KNX, in spite of being 12 miles closer (99 vs 111). I think it's primarily the partial saltwater path for KNX in my case, though. At a friend's house in Moreno Valley, as well as at my grandma's house in San Gabriel, KFI is considerably stronger, like 10-15 dB. There is a very efficient station that I believe doesn't have ground radials - 1530 KFBK in Sacramento, CA. Also I suspect 1500 KSTP St Paul, MN's daytime site may also not have ground radials, but I'm not totally positive on that one. 73, Stephen Sent from my iPad ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Short antenna radials
Did you mean that KSTP night facilities? I'm just trying to understand because I'm just an amateur. If it is their day facilities is it because that tower is taller than most? Confused, Todd in Woodbury Mn Sony ICF 2010, Toyota car radio On Dec 1, 2013 8:37 AM, "Mark Durenberger" wrote: > To add to Dennis' info: The KSTP antenna was/is a 179.4/179.4 and appears > to be considered a "Sectional" rather than a Franklin by the FCC. > Nit-picking' I guess. > > Happy Holidays! > > Regards, > > Mark Durenberger > > > -Original Message- From: Dennis Gibson > Sent: Saturday, November 30, 2013 10:26 PM > To: irca@hard-core-dx.com > Subject: Re: [IRCA] Short antenna radials > > KFI's original tower was there before the industrial complex was built. > The new tower was built at the same place as the old and uses the same > ground radials. > > KFBK and the KSTP day site both use Franklin antennas, the only two in the > country. A Franklin antenna consists of two 180 degree electrical height > (one half wavelength) antennas separated by an insulator, stacked > vertically and fed at the center. The top half radiates and the bottom half > is the ground. There are no ground radials. > > Date: Sat, 30 Nov 2013 13:50:34 -0800 (PST) > From: Stephen Airy > To: w7...@yahoo.com, irca@hard-core-dx.com > Subject: Re: [IRCA] Short antenna radials > > I've been recently wondering about this myself (short-radial efficiency, > or lack thereof), but more from the standpoint of low-power part 15 > transmitting setups. One example I'm thinking of is such that the total > length of the antenna AND all ground radials is 3 meters, and does it make > much difference if you use a base-fed radiator with radials vs a center-fed > segmented short dipole without radials. (The rule in 15.219 specifies the > antenna, transmission line, and ground lead cannot exceed 3 meters.) > There's other scenarios I'm wondering about, but I'll leave them off as I > think it's beyond the scope of this list. > > As for KFI, I believe the original tower was there long before the > industrial complex was built. So, I think there could be ground radials > there already, and the new tower was hooked up to them? Or maybe they have > another way of grounding it. KFI *is* a few dB weaker at my house than KNX, > in spite of being 12 miles closer (99 vs 111). I think it's primarily the > partial saltwater path for KNX in my case, though. At a friend's house in > Moreno Valley, as well as at my grandma's house in San Gabriel, KFI is > considerably stronger, like 10-15 dB. > > There is a very efficient station that I believe doesn't have ground > radials - 1530 KFBK in Sacramento, CA. Also I suspect 1500 KSTP St Paul, > MN's daytime site may also not have ground radials, but I'm not totally > positive on that one. > > 73, Stephen > > Sent from my iPad > ___ > IRCA mailing list > IRCA@hard-core-dx.com > http://montreal.kotalampi.com/mailman/listinfo/irca > > Opinions expressed in messages on this mailing list are those of the > original contributors and do not necessarily reflect the opinion of the > IRCA, its editors, publishing staff, or officers > > For more information: http://www.ircaonline.org > > To Post a message: irca@hard-core-dx.com > ___ > IRCA mailing list > IRCA@hard-core-dx.com > http://montreal.kotalampi.com/mailman/listinfo/irca > > Opinions expressed in messages on this mailing list are those of the > original contributors and do not necessarily reflect the opinion of the > IRCA, its editors, publishing staff, or officers > > For more information: http://www.ircaonline.org > > To Post a message: irca@hard-core-dx.com > > ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Short antenna radials
Yes indeed. They are 179.4 degrees. Scott Fybush once wrote that it is a Franklin. We got a tour of the KSTP day site during the joint convention and I think he called it a Franklin then. Perhaps there is a difference of opinion. A unique and extremely efficient antenna no matter want you call it. Date: Sun, 1 Dec 2013 08:36:35 -0600 From: "Mark Durenberger" To: "Mailing list for the International Radio Club of America" Subject: Re: [IRCA] Short antenna radials To add to Dennis' info: The KSTP antenna was/is a 179.4/179.4 and appears to be considered a "Sectional" rather than a Franklin by the FCC. Nit-picking' I guess. Happy Holidays! Regards, Mark Durenberger Sent from my iPad ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Short antenna radials
180 degree (or vicinity) towers are uncommon; especially on the low end of the band. Many are used by 50 KW stations. The KSTP night signal is directional with a sharp null to the east southeast to protect WFED in Washington DC. For some reason the three night towers are different heights; 216.5 degrees (184 degrees and 32.5 degrees of top loading), 184 degrees and 160 degrees. I don't know why. For reference 180 degrees is one half wavelength and 90 degrees (very common) is one quarter wavelength. Here's an interesting chart. http://www.eriinc.com/Files/fc/fcec575c-5a91-455b-bcfa-5b8bf0d5ff1b.pdf Here's a wavelength converter to change degrees to height or vice versa. All AM tower heights on the FCC website are in electrical degrees. http://www.jampro.com/uploads/tech_calc/wavelength.htm Date: Sun, 1 Dec 2013 13:02:30 -0600 From: Forrest Skaine To: IRCA Mailing list for the International Radio Club of America Subject: Re: [IRCA] Short antenna radials Did you mean that KSTP night facilities? I'm just trying to understand because I'm just an amateur. If it is their day facilities is it because that tower is taller than most? Confused, Todd in Woodbury Mn Sent from my iPad ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Short antenna radials
No...that's referring to the Day "Franklin." The tower height is related to the frequency. To build a Franklin you'd need twice the "normal" tower height, so a Franklin or "Baby Franklin" are practical only at the higher frequencies where wavelengths are shorter. (FYI: KSTP's nighttime array uses antennas that are closer to the 'normal' length for 1500...though a bit short). So, yes, KSTP's high tower height is because they chose to install a Franklin-type antenna. SE Hubbard wanted to give his station every advantage. While being on 1500 is a disadvantage (compared for example to WCCO at 830)** the use of a Franklin approach helped to slightly overcome that difference. ** Some propagation charts suggest there's a 6 db difference between coverage from 830 and 1500. That would mean KSTP (using a normal antenna) would have needed 4 times WCCO's power, or 200,000 watts to match WCCO's Field Strength. (Of course in the practical world the difference is probably not that great.) Mark Durenberger On the Road -Original Message- From: Forrest Skaine Sent: Sunday, December 01, 2013 1:02 PM To: IRCA Mailing list for the International Radio Club of America Subject: Re: [IRCA] Short antenna radials Did you mean that KSTP night facilities? I'm just trying to understand because I'm just an amateur. If it is their day facilities is it because that tower is taller than most? Confused, Todd in Woodbury Mn Sony ICF 2010, Toyota car radio On Dec 1, 2013 8:37 AM, "Mark Durenberger" wrote: To add to Dennis' info: The KSTP antenna was/is a 179.4/179.4 and appears to be considered a "Sectional" rather than a Franklin by the FCC. Nit-picking' I guess. Happy Holidays! ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Short antenna radials
You both have been very helpful in beginning to understand the schematics of antennas. Todd in Woodbury Mn Sony ICF 2010, Toyota car radio On Dec 2, 2013 2:07 PM, "Mark Durenberger Mobile" wrote: > No...that's referring to the Day "Franklin." > > The tower height is related to the frequency. To build a Franklin you'd > need twice the "normal" tower height, so a Franklin or "Baby Franklin" are > practical only at the higher frequencies where wavelengths are shorter. > (FYI: KSTP's nighttime array uses antennas that are closer to the 'normal' > length for 1500...though a bit short). > > So, yes, KSTP's high tower height is because they chose to install a > Franklin-type antenna. SE Hubbard wanted to give his station every > advantage. While being on 1500 is a disadvantage (compared for example to > WCCO at 830)** the use of a Franklin approach helped to slightly overcome > that difference. > > > ** Some propagation charts suggest there's a 6 db difference between > coverage from 830 and 1500. That would mean KSTP (using a normal antenna) > would have needed 4 times WCCO's power, or 200,000 watts to match WCCO's > Field Strength. (Of course in the practical world the difference is > probably not that great.) > > > Mark Durenberger > On the Road > > -Original Message----- From: Forrest Skaine > Sent: Sunday, December 01, 2013 1:02 PM > To: IRCA Mailing list for the International Radio Club of America > Subject: Re: [IRCA] Short antenna radials > > Did you mean that KSTP night facilities? I'm just trying to understand > because I'm just an amateur. If it is their day facilities is it because > that tower is taller than most? > Confused, > Todd in Woodbury Mn > Sony ICF 2010, Toyota car radio > On Dec 1, 2013 8:37 AM, "Mark Durenberger" wrote: > > To add to Dennis' info: The KSTP antenna was/is a 179.4/179.4 and appears >> to be considered a "Sectional" rather than a Franklin by the FCC. >> Nit-picking' I guess. >> >> Happy Holidays! >> > > ___ > IRCA mailing list > IRCA@hard-core-dx.com > http://montreal.kotalampi.com/mailman/listinfo/irca > > Opinions expressed in messages on this mailing list are those of the > original contributors and do not necessarily reflect the opinion of the > IRCA, its editors, publishing staff, or officers > > For more information: http://www.ircaonline.org > > To Post a message: irca@hard-core-dx.com > > ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Short antenna radials
AM antenna systems (especially directionals) are fascinating to me. Below is a post from about two years ago that was on another list where Franklin antenna systems were being discussed. This post is about KFBK 1530. I think the other true Franklin in the United States was at WNBF 1290 Binghamton New York. I don't think it is being used now because of the center insulator failing in some way. Tom ** Begin Quote ** The two towers are used at all times (DA-2, one of the few Class As to operate in this mode). Both are 180 degrees over 180 degrees, a total of 360 degrees, so these are true Franklins (only one other exists in the U.S., and it is ND-D). The efficiency of each is 510 mV/m/kW at 1 km, which is about 99 kW out from 50 kW in. The feed system is also home-built, using not the usual, for 50 kW, six wires (two central wires plus four surrounding wires), but EIGHT wires (two central wires plus six surrounding wires). This system is still in place and is used 24/7/365 by one of California's six Class As. The feed system incorporates a matching system at the base, horizontal to the vertical tower, and a vertical run up one-half of the tower height of nearly 640 feet to the sectionalizing insulator where a network is present. This vertical run is also eight wires. Legend has it that the FCC inspector demanded that a ground system be installed, and I guess one was, but it was very soon abandoned. There is no longer any strap from the bottom of the base insulator to what would be the "ground". ** End Quote ** ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
