Re: [Elecraft] Antennas in the attic
A poor antenna has infinite gain over no antenna. 73, Bob K2TK ex KN2TKR (1956) & K2TKR __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Antennas in the attic
When I built my present (brick and frame) home in 1996 I was fortunate enough to work with my builder and architect and had them design the attic to be void of all HVAC ductwork, AC wiring, low voltage wiring (alarm and telephone) and stereo speaker leads. The builder thought I was a kook (not entirely wrong). The builder made me two "catwalks" out from the center of the attic to the far ends so I could get to dipole ends to adjust for resonance ($800 total). Today, in my attic, I have: Alpha Delta-DX-EE (40-20-15-10) Homebrew WARC fan dipole (30-17-12) 3-ele 6M yagi on rotator Stacked AEA 6M halos 10M groundplane 2M Msquare "Eggbeater" 70 cm Msquare "Eggbeater" 5-ele 2M yagi (vertically) 2M/440 satellite AZ-EL array 2 DC to daylight "Discones" Delta loop on and SGC-230 coupler 6M dipole 2M yagi - 2.3 GHz "BBQ Grill" AZ-EL sat antenna array All compromise antennas, obviously, but they all work and each is "better than a sharp stick in the eye". 73 Terry, WØFM -Original Message- From: Jack Smith [mailto:jack.sm...@cliftonlaboratories.com] Sent: Tuesday, August 13, 2013 4:19 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Antennas in the attic In years past, part of my work involved signal propagation (VHF/UHF) predictions and measurements. For 150 MHz paging service, the generally accepted in-building attenuation figure was on the order of 10 to 20 dB compared with an outdoor measurement in the same location. 10 dB or so for typical timber framed residential construction, 20 dB for reinforced concrete commercial or multi-unit residential construction, and 30 dB in some particularly difficult environments with many interior walls and with high local noise, such as a telephone company switching center. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Antennas in the attic
Folks - We are exceeding the single list posting topic limit for the subjects on loops and attic antennas. Let's close the threads at this time in the interest of keeping list noise level under control. 73, Eric Elecraft List Moderator elecraft.com Eric elecraft.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Antennas in the attic
OK, OK My only intent was to suggest that attic antennas are sometimes surprisingly good and not to forget your VHF/UHF bands as in typical wood-frame houses work pretty good. Yes there is absorption by the roof and walls but so it there in a forest or in the downtown urban concrete "jungle". Experiment and you may be surprised. How hard is it to put a vertical whip up in the attic? Well, that depends on access but it is not as involved as erecting a 100-foot tower with stacked beams for 10, 15 and 20m. I am lucky because I have nearly 2-acres in the country with no restrictions. I can put all the antennas I desire. My point was we were not sure how well the TV antenna would work - it did surprising well. For those of you with restrictions it is an option to consider. I would never advise someone to install a 1296-MHz antenna inside (yet some have had success shooting a small yagi thru a window). It is well known that absorption increases with frequency so best results are high and clear with as much gain as you can muster. If VHF/UHF = FM, repeaters make up a lot of deficiencies. But it may surprise some of you that many hams work CW/SSB on VHF+. Interaction with home electronics is a risk. A lot of that depends on freq. and RF power. Many years ago (oh no here we go again) I worked as a student employee at the university's cyclotron lab. My job was calibrating the radiation counters. "Atom Smashers" utilize very high power RF and, guess what happened? The RF got into the detectors setting them off. That is not a nice thing to do in a high intensity radiation facility It was surprising there were no heart attacke over this. I learned RFI abatement at a young age. 73, Ed - KL7UW http://www.kl7uw.com dubus...@gmail.com "Kits made by KL7UW" __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Antennas in the attic
In years past, part of my work involved signal propagation (VHF/UHF) predictions and measurements. For 150 MHz paging service, the generally accepted in-building attenuation figure was on the order of 10 to 20 dB compared with an outdoor measurement in the same location. 10 dB or so for typical timber framed residential construction, 20 dB for reinforced concrete commercial or multi-unit residential construction, and 30 dB in some particularly difficult environments with many interior walls and with high local noise, such as a telephone company switching center. Almost all the recent literature concentrates on 800 MHz and upward, but LP. Rice's classic paper from 1959, Radio Transmission into Buildings at 35 and 150 MHz, published in the January 1959 Bell System Technical Journal still is worthwhile reading. A copy is available at http://www3.alcatel-lucent.com/bstj/vol38-1959/articles/bstj38-1-197.pdf -- however, Rice's study considered only commercial type buildings in the New York City area. An attic mounted antenna should exhibit less loss than the roughly 10 dB figure for residential work at 150 MHz since some allowance for interior walls is included in the 10 dB figure and an attic antenna only looks through the roof. Some - perhaps nearly all - of this excess loss will be offset by the increased height of the attic antenna compared with the same antenna on a ground or second story floor. As a really rough estimate, doubling the antenna height above ground level yields 6 dB increase in signal level. There are lots of caveats in this rule, but if one is doing back of the envelope estimates it's still a useful concept. Therefore, I would expect, as a rough and ready estimate an antenna at 12 feet above ground in the attic to work about as well as the same antenna outside at 5 or 6 feet above ground. Jack K8ZOA On 8/13/2013 4:42 PM, Ron D'Eau Claire wrote: Keep in mind that absorption by the walls, roof, etc. increases with frequency. That's why a microwave oven will heat your dinner but no amount of 40 meter signal will do a thing for it. Still, I've had good success with a J-pole in the attic. No weak signal DX work, but a good local signal. 73, Ron AC7AC -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Mike WA8BXN Sent: Tuesday, August 13, 2013 11:58 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Antennas in the attic Remember things are different on VHF/UHF bands. Its often FM which reduces noise problems to some extent, and the wavelengths are shorter and get out between conductors a lot better than HF. 73 - Mike WA8BXN __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Antennas in the attic
Keep in mind that absorption by the walls, roof, etc. increases with frequency. That's why a microwave oven will heat your dinner but no amount of 40 meter signal will do a thing for it. Still, I've had good success with a J-pole in the attic. No weak signal DX work, but a good local signal. 73, Ron AC7AC -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Mike WA8BXN Sent: Tuesday, August 13, 2013 11:58 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Antennas in the attic Remember things are different on VHF/UHF bands. Its often FM which reduces noise problems to some extent, and the wavelengths are shorter and get out between conductors a lot better than HF. 73 - Mike WA8BXN __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Antennas in the attic
I've had two meter and UHF antennas in the attic without issues. I also have two perpendicular 40M and two perpendicular 20M dipoles in the attic of my house. Up to a year ago, all was fine with my K3 running 100W, either band. Now, if I transmit as low as 20W on one of the 40M dipoles, it instantly sets off the fire/smoke detectors in my home security system. These fire/smoke detectors are probably 15 or more years old, the whole security system is wired. Most of the wiring IS in the attic, so no big surprise. The 40M dipoles do get our really well, even in the attic. Since the fire/smoke detectors are being triggered, they set off the whole alarm, including calling the monitoring service, whether the alarm system is set (enabled) or not. The SWR on the primary offending 40M dipole has a very low SWR, less than 1.2:1 at 7.23MHz. I'm now researching chokes and bypass caps, and maybe rewiring the smoke detectors with shielded cables. The security system hasn't a clue So, getting out is not the only issue 73, Terry, WB4JFI -Original Message- From: Mike WA8BXN Sent: Tuesday, August 13, 2013 2:57 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Antennas in the attic Remember things are different on VHF/UHF bands. Its often FM which reduces noise problems to some extent, and the wavelengths are shorter and get out between conductors a lot better than HF. 73 - Mike WA8BXN ---Original Message--- From: Phil Kane Date: 8/13/2013 2:40:41 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Antennas in the attic On 8/13/2013 9:56 AM, Edward R Cole wrote: So this suggests that VHF and UHF ham antennas can also work in attics. For several years I used a 2-m mag-mount antenna upside-down on the ductwork in the plenum area above my office - 3rd floor of a 6-story building. Had no problem reaching repeaters 30+ miles away. "Radio is magic" 73 de K2ASP - Phil Kane Elecraft K2/100 s/n 5402 From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Antennas in the attic
Remember things are different on VHF/UHF bands. Its often FM which reduces noise problems to some extent, and the wavelengths are shorter and get out between conductors a lot better than HF. 73 - Mike WA8BXN ---Original Message--- From: Phil Kane Date: 8/13/2013 2:40:41 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Antennas in the attic On 8/13/2013 9:56 AM, Edward R Cole wrote: > So this suggests that VHF and UHF ham antennas can also work in attics. For several years I used a 2-m mag-mount antenna upside-down on the ductwork in the plenum area above my office - 3rd floor of a 6-story building. Had no problem reaching repeaters 30+ miles away. "Radio is magic" 73 de K2ASP - Phil Kane Elecraft K2/100 s/n 5402 >From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Antennas in the attic
On 8/13/2013 9:56 AM, Edward R Cole wrote: > So this suggests that VHF and UHF ham antennas can also work in attics. For several years I used a 2-m mag-mount antenna upside-down on the ductwork in the plenum area above my office - 3rd floor of a 6-story building. Had no problem reaching repeaters 30+ miles away. "Radio is magic" 73 de K2ASP - Phil Kane Elecraft K2/100 s/n 5402 >From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Antennas in the attic
I have use M2 6/2/432 loops on a mobile stack mount in my attic that works quite well out to 50+ miles. I placed these up there for emergency use in case of a weather event taking out my outdoor antennas. I have used them from QRP to 1k on 6m and have preamps for each. A 160m loop- is a favorite of mine and have one on all bands 6-160m. Do not have one up at this time but plan on another in the future. 73, Fred/N0AZZ -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Edward R Cole Sent: Tuesday, August 13, 2013 11:57 AM To: Elecraft@mailman.qth.net Subject: [Elecraft] Antennas in the attic Slightly off topic. A few years ago my parents built a small home on the farm pond in a corner parcel of their former farm (which they sold at retirement - age 77). One problem was TV reception and they didn't want to install an outside mast and antenna. I helped them select a medium sized VHF/UHF TV antenna (typical modified log-perodic-yagi) and we searched for a way into the attic. It was not going to be fun in tight quarters with fiberglass batting. Then it occurred to me their 2-1/2 car garage had open rafters. So I took the antenna with elements still folded up there and unfolded it pointing toward the nearest station (about 35mi). A few years later they ended up with a DSS dish on the side of the house. Worked quite well without a preamp (TV booster) even on a couple UHF stations. RG6 was used to connect to their TV. So this suggests that VHF and UHF ham antennas can also work in attics. 73, Ed - KL7UW http://www.kl7uw.com dubus...@gmail.com "Kits made by KL7UW" __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html - No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2242 / Virus Database: 3211/6074 - Release Date: 08/13/13 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
