---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 02/28/13: 15 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:31 AM - Re: Ground plane diameter (Bob Verwey) 2. 06:58 AM - Re: Ground plane diameter (Robert L. Nuckolls, III) 3. 08:13 AM - Re: Speakers for helmet installation (Eric M. Jones) 4. 08:13 AM - Re: Ground plane diameter (Bob Verwey) 5. 09:06 AM - Re: Ground plane diameter (Robert L. Nuckolls, III) 6. 09:07 AM - Re: Ground plane diameter (Christopher Cee Stone) 7. 09:37 AM - Re: Ground plane diameter (Fisher Paul A.) 8. 09:55 AM - Re: Ground plane diameter (Paul Thomson) 9. 10:01 AM - Re: Ground plane diameter (Christopher Cee Stone) 10. 10:36 AM - Re: Ground plane diameter (Robert L. Nuckolls, III) 11. 10:53 AM - Re: Re: Speakers for helmet installation (Richard Girard) 12. 10:57 AM - Re: Ground plane diameter (Robert L. Nuckolls, III) 13. 11:07 AM - Re: Ground plane diameter (Robert L. Nuckolls, III) 14. 11:49 AM - Re: Eye Beam Mini LED / RF interference (Eric M. Jones) 15. 12:24 PM - Re: Speakers for helmet installation (Peter Pengilly) ________________________________ Message 1 _____________________________________ Time: 01:31:51 AM PST US Subject: Re: AeroElectric-List: Ground plane diameter From: Bob Verwey If we consider the simple whip antenna for our VHF comms, what is the best trimmed length for the antenna part and the ground plane diameter to optimise the frequencies in the early '120's? Best... Bob Verwey On 26 February 2013 19:02, R. curtis wrote: > mrspudandcompany@verizon.net> > > >> At 10:27 PM 2/25/2013, you wrote: >> >>> OK, thanks Bob. It operates on 978 Mhz so I probably could have figured >>> it out by breaking out my ARRL Antenna Book but I guess I was just a bit >>> on the lazy side. >>> >> >> Very good. Yes, 978 MHz does work out to >> a 6" diameter ground plane . . . >> > > > I have seen often that antennas get cut off to tune > for maximum radiation. Is the ground plane as > critical in dimension as the radiating element? > > Roger > > -- > > Do you have a slow PC? Try a Free scan http://www.spamfighter.com/** > SLOW-PCfighter?cid=sigen > > ________________________________ Message 2 _____________________________________ Time: 06:58:00 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Ground plane diameter At 03:29 AM 2/28/2013, you wrote: >If we consider the simple whip antenna for our VHF comms, what is >the best trimmed length for the antenna part and the ground plane >diameter to optimise the frequencies in the early '120's? Center of the VHF comm spectrum is (118+135)/2 or 127.5 MHz Free space full wavelength in meters is 300/127.5 = 2.35M 2.35M x 39.34 in/meter yields 92" 1/4 wave radials (or antennas) at 127.5 are 92/4 or 23". Bob . . . ________________________________ Message 3 _____________________________________ Time: 08:13:45 AM PST US Subject: AeroElectric-List: Re: Speakers for helmet installation From: "Eric M. Jones" > All, I fly a trike wearing a full face Shoei helmet. While the helmet doesn't seal my ears like headphones ........... Can anyone recommend a particular speaker or mic cartridge that has worked for you? > Rick Girard Dear Rick, Not only is there technical skill on this website, but good advice too, I hope. The problem you are having is called "Target Fixation". What you need to do is sit down and imagine how to get where you want to be without adding unnecessary restraints such as "finding a use for a Shoei helmet". Or in other words, use the right tool for the job. There are helmets with built in headphones and full face-shields too. No problem. One powerfull tool I have used is to just sell one device on Ebay and buy what you need there too. Bada bing bada boom.... -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones(at)charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=395274#395274 ________________________________ Message 4 _____________________________________ Time: 08:13:48 AM PST US Subject: Re: AeroElectric-List: Ground plane diameter From: Bob Verwey Thanks Bob, Care to elaborate on the ground plane a little? If the structure of the aircraft is 'Cub-like' steel tubing, and one mounts the antenna on the roof, is it sufficient to use the airframe as the groundplane? Bob Verwey On 28 February 2013 16:53, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > nuckolls.bob@aeroelectric.com**> > > At 03:29 AM 2/28/2013, you wrote: > >> If we consider the simple whip antenna for our VHF comms, what is the >> best trimmed length for the antenna part and the ground plane diameter to >> optimise the frequencies in the early '120's? >> > > Center of the VHF comm spectrum is (118+135)/2 or 127.5 MHz > > Free space full wavelength in meters is 300/127.5 = 2.35M > > 2.35M x 39.34 in/meter yields 92" > > 1/4 wave radials (or antennas) at 127.5 are > 92/4 or 23". > > > Bob . . . > > ________________________________ Message 5 _____________________________________ Time: 09:06:28 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Ground plane diameter At 10:10 AM 2/28/2013, you wrote: >Thanks Bob, > >Care to elaborate on the ground plane a little? If the structure of >the aircraft is 'Cub-like' steel tubing, and one mounts the antenna >on the roof, is it sufficient to use the airframe as the groundplane? ANY conductive material can be brought into service as a 'ground'. Given our unique line-of-sight, short-range expectations for radio communications, a wet-string would probably serve 96% of your communications expectations. Consider the lowly hand-held. Talk about compromised ground planes!! The rubber duck in a sweaty fist works for some situations, other situations (mostly driven by customer's willingness to pay) are optimized to the best-we-know-how-to-do. Most of us will secure happiness with some intermediate but decidedly less expensive configuration. ANY combination you choose to try should be first tailored for lowest possible SWR over the range of interest. The transmitter has no idea what's at the other end of the feedline. Gross efficiency and/or radiation patterns are separate issues not easily measured and massaged. Are there things we could do that are 'better' than using a rag-covered-tube ground plane? Sure. Would the guy at the other end of the link know the difference? Probably not. This is but one of several advantages we enjoy over the drivers of TC iron, we can try it. If found insufficient to design goals, do something different. Bob . . . ________________________________ Message 6 _____________________________________ Time: 09:07:18 AM PST US Subject: Re: AeroElectric-List: Ground plane diameter From: Christopher Cee Stone Bob... I follow your calcs and the underlying physics until I see the 300/127.5 2.35M. Where is the 300 from? What does it represent? Always learning! Chris Stone On Thu, Feb 28, 2013 at 6:53 AM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > nuckolls.bob@aeroelectric.com**> > > > At 03:29 AM 2/28/2013, you wrote: > >> If we consider the simple whip antenna for our VHF comms, what is the >> best trimmed length for the antenna part and the ground plane diameter to >> optimise the frequencies in the early '120's? >> > > Center of the VHF comm spectrum is (118+135)/2 or 127.5 MHz > > Free space full wavelength in meters is 300/127.5 = 2.35M > > 2.35M x 39.34 in/meter yields 92" > > 1/4 wave radials (or antennas) at 127.5 are > 92/4 or 23". > > > Bob . . . > > ________________________________ Message 7 _____________________________________ Time: 09:37:20 AM PST US From: "Fisher Paul A." Subject: RE: AeroElectric-List: Ground plane diameter SeKAmWQgbGlrZSB0byB0cnkgdG8gYW5zd2VyIHRoaXM6DQoNCjMwMCBtaWxsaW9uIG1ldGVycyBw ZXIgc2Vjb25kIGlzIHJvdWdobHkgdGhlIHNwZWVkIG9mIGxpZ2h0IOKAkyBhbHNvIGFib3V0IHRo ZSBzcGVlZCB0aGUgcmFkaW8gd2F2ZXMgcHJvcGFnYXRlLiAgRGl2aWRpbmcgdGhpcyBieSB0aGUg ZnJlcXVlbmN5IGluIG1lZ2FoZXJ0eiBnaXZlcyB5b3UgdGhlIHdhdmUgbGVuZ3RoLiBTbyAzMDAs MDAwLDAwMC8xMjcsNTAwLDAwMCA9IDIuMzUgbWV0ZXJzLg0KDQoNCnNlZW1zIGxpa2UgdGhpcyB3 YXMgb24gdGhlIHRlc3QgZm9yIG15IGhhbSBsaWNlbnNl4oCmIHN1cnByaXNpbmcgSSBzdGlsbCBy ZW1lbWJlciBpdCENCg0KUGF1bCBGaXNoZXINCg0KDQpGcm9tOiBvd25lci1hZXJvZWxlY3RyaWMt bGlzdC1zZXJ2ZXJAbWF0cm9uaWNzLmNvbSBbbWFpbHRvOm93bmVyLWFlcm9lbGVjdHJpYy1saXN0 LXNlcnZlckBtYXRyb25pY3MuY29tXSBPbiBCZWhhbGYgT2YgQ2hyaXN0b3BoZXIgQ2VlIFN0b25l DQpTZW50OiBUaHVyc2RheSwgRmVicnVhcnkgMjgsIDIwMTMgMTE6MDcgQU0NClRvOiBhZXJvZWxl Y3RyaWMtbGlzdEBtYXRyb25pY3MuY29tDQpTdWJqZWN0OiBSZTogQWVyb0VsZWN0cmljLUxpc3Q6 IEdyb3VuZCBwbGFuZSBkaWFtZXRlcg0KDQpCb2IuLi4NCg0KSSBmb2xsb3cgeW91ciBjYWxjcyBh bmQgdGhlIHVuZGVybHlpbmcgcGh5c2ljcyB1bnRpbCBJIHNlZSB0aGUgMzAwLzEyNy41ID0gMi4z NU0uICBXaGVyZSBpcyB0aGUgMzAwIGZyb20/IFdoYXQgZG9lcyBpdCByZXByZXNlbnQ/DQoNCkFs d2F5cyBsZWFybmluZyENCg0KQ2hyaXMgU3RvbmUNCg0K ________________________________ Message 8 _____________________________________ Time: 09:55:54 AM PST US From: Paul Thomson Subject: Re: AeroElectric-List: Ground plane diameter Then would be the recommendation for a more modern design that is all carbo n fiber?- The carbon is conductive, but absorbs radiation instead of refl ecting it from what I understand.- Go with a foil circle or strips of the appropriate diameter on the outside of the carbon, but under the paint?- =0A=0AThanks=0A=0APaul=0A=0A=0A=0A=0A________________________________=0A F rom: "Robert L. Nuckolls, III" =0ATo: aeroel ectric-list@matronics.com =0ASent: Thursday, February 28, 2013 11:05 AM=0AS ubject: Re: AeroElectric-List: Ground plane diameter=0A =0A--> AeroElectric -List message posted by: "Robert L. Nuckolls, III" =0A=0AAt 10:10 AM 2/28/2013, you wrote:=0A> Thanks Bob,=0A> =0A> Car e to elaborate on the ground plane a little? If the structure of the aircra ft is 'Cub-like' steel tubing, and one mounts the antenna on the roof, is i t sufficient to use the airframe as the groundplane?=0A=0A- ANY conductiv e material can be brought into service=0A- as a 'ground'. Given our uniqu e line-of-sight, short-range=0A- expectations for radio communications, a wet-string would=0A- probably serve 96% of your communications expectati ============= ________________________________ Message 9 _____________________________________ Time: 10:01:22 AM PST US Subject: Re: AeroElectric-List: Ground plane diameter From: Christopher Cee Stone Ahhh... Yes. Still mired in English units 186,000 miles per second. Thanks! chris stone On Thu, Feb 28, 2013 at 9:34 AM, Fisher Paul A. wrote: > I=99d like to try to answer this:**** > > ** ** > > 300 million meters per second is roughly the speed of light =93 als o about > the speed the radio waves propagate. Dividing this by the frequency in > megahertz gives you the wave length. So 300,000,000/127,500,000 = 2.35 > meters. **** > > ** ** > > ** ** > > seems like this was on the test for my ham license surprising I still > remember it!**** > > ** ** > > Paul Fisher**** > > ** ** > > ** ** > > *From:* owner-aeroelectric-list-server@matronics.com [mailto: > owner-aeroelectric-list-server@matronics.com] *On Behalf Of *Christopher > Cee Stone > *Sent:* Thursday, February 28, 2013 11:07 AM > *To:* aeroelectric-list@matronics.com > *Subject:* Re: AeroElectric-List: Ground plane diameter**** > > ** ** > > Bob...**** > > ** ** > > I follow your calcs and the underlying physics until I see the 300/127.5 > 2.35M. Where is the 300 from? What does it represent?**** > > ** ** > > Always learning!**** > > ** ** > > Chris Stone**** > > ** ** > ________________________________ Message 10 ____________________________________ Time: 10:36:06 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Ground plane diameter At 11:48 AM 2/28/2013, you wrote: >Then would be the recommendation for a more modern design that is >all carbon fiber? The carbon is conductive, but absorbs radiation >instead of reflecting it from what I understand. Go with a foil >circle or strips of the appropriate diameter on the outside of the >carbon, but under the paint? That's a whole other can of worms. The carbon fiber is, as you've described, pretty lossy stuff. Yeah, it is conductive but much of electrical energy flowing through a carbon matrix is converted to heat. Trying to create idealized ground planes over the carbon and under the paint is exceedingly expensive and problematic for affecting structural integrity of the shell. At HBC, non-resonant ground planes were bonded to the inside surface of the fuselage shell. Relatively inexpensive and the flight test results deemed them adequate to the task. Bob . . . ________________________________ Message 11 ____________________________________ Time: 10:53:19 AM PST US Subject: Re: AeroElectric-List: Re: Speakers for helmet installation From: Richard Girard Eric, I've flown with the Com-tronics helmet when I was getting my WSC endorsement. It was all right, but I have a reason for wanting the Shoei. They have saved my life once and my looks twice. In every incident, the helmet took the blow and I escaped without so much as a headache. So you can understand why I like having a jaw bar that I know will keep the ground and debris away from my mug. Rick On Thu, Feb 28, 2013 at 10:12 AM, Eric M. Jones wrote: > emjones@charter.net> > > > > All, I fly a trike wearing a full face Shoei helmet. While the helmet > doesn't seal my ears like headphones ........... Can anyone recommend a > particular speaker or mic cartridge that has worked for you? > > Rick Girard > > > Dear Rick, > > Not only is there technical skill on this website, but good advice too, I > hope. > > The problem you are having is called "Target Fixation". What you need to > do is sit down and imagine how to get where you want to be without adding > unnecessary restraints such as "finding a use for a Shoei helmet". Or in > other words, use the right tool for the job. There are helmets with built > in headphones and full face-shields too. No problem. > > One powerfull tool I have used is to just sell one device on Ebay and buy > what you need there too. > > Bada bing bada boom.... > > -------- > Eric M. Jones > www.PerihelionDesign.com > 113 Brentwood Drive > Southbridge, MA 01550 > (508) 764-2072 > emjones(at)charter.net > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=395274#395274 > > -- Zulu Delta Mk IIIC Thanks, Homer GBYM It isn't necessary to have relatives in Kansas City in order to be unhappy. - Groucho Marx ________________________________ Message 12 ____________________________________ Time: 10:57:55 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Ground plane diameter At 11:34 AM 2/28/2013, you wrote: >Id like to try to answer this: > >300 million meters per second is roughly the >speed of light also about the speed the radio >waves propagate. Dividing this by the frequency >in megahertz gives you the wave length. So >300,000,000/127,500,000 = 2.35 meters. > > >seems like this was on the test for my ham >license surprising I still remember it!> Yeah, pretty cool stuff. First learned to do those calculations on a slide rule about 60 years ago . . . Bob . . . ________________________________ Message 13 ____________________________________ Time: 11:07:04 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Ground plane diameter I'd forgotten about a compendium of antenna articles that were waiting to be posted to the website. I just put them up where they can be downloaded and inquiring minds can exploit as appropriate: http://tinyurl.com/d2ql8lw Bob . . . ________________________________ Message 14 ____________________________________ Time: 11:49:45 AM PST US Subject: AeroElectric-List: Re: Eye Beam Mini LED / RF interference From: "Eric M. Jones" Perihelion Design sells an extremely versatile LED light too. See: www.PerihelionDesign.com These are made from the Loc-Line snap together coolant line parts. Dimmers are available too. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones(at)charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=395308#395308 Attachments: http://forums.matronics.com//files/led_goosenecks_892.pdf ________________________________ Message 15 ____________________________________ Time: 12:24:45 PM PST US From: Peter Pengilly Subject: Re: AeroElectric-List: Speakers for helmet installation Have you tried a motorcycle intercom kit? There are several available (I only have links for UK companies, but there must be a few stateside). They typically supply small speakers that velcro into the helmet and a microphone that glues into the chin bar with wires hidden behind the the lining. Equally they have plugs that will disconnect easily when you forget to unplug ... Peter On 27/02/2013 23:55, Richard Girard wrote: > All, I fly a trike wearing a full face Shoei helmet. While the helmet > doesn't seal my ears like headphones it does cut down the noise > considerably. It also cuts out my ability to hear my radio so I want > to put speakers and a small mic in the helmet. I did this once before > cannabalizing a Cobra VOX family radio for hang gliding. I don't want > to cannabalize my David Clarks this time so the speakers and mic will > be compatible with my hand held (a Vertex). Mouser has lots of mylar > diaphragm speakers of the right size and depth. Can anyone recommend a > particular speaker or mic cartridge that has worked for you? > > Rick Girard > Do not archive > > -- > Zulu Delta > Mk IIIC > Thanks, Homer GBYM > > It isn't necessary to have relatives in Kansas City in order to be > unhappy. > - Groucho Marx > > * > > > * ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.