Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
Search
MTT4BT Installation on ATV/Motorcycle - Antenna Pattern
|
FYI, Everyone has seen the full spherical radiation pattern of a dipole and the
toggle quoted message
Show quoted text
hemisphere pattern of a 1/4 wave over groundplane with an additional 3 dB gain Bit it is not valid in most cases. No matter how you mount the antenna to its "ground plane" it will not have a hemisphere pattern unless the ground plane is an INFINITE sheet of metal in all directions. Similarly it wont have the added 3 dB gain either. The radials or metal of the small vehicle will in fact, lend to a match to the coax, but it does little to the antenna pattern. At any distance from a raised radial ground plane antenna, it will still be an omni pattern. The radials, etc only help provide a match. Of course on a car or s omethign approaching the size of a wavelength, then there will be a pattern developed. But not due to radials on a raised "ground plane" antenna. Just sayin. Bob,wb4apr On Sat, Sep 18, 2021 at 11:23 AM Allen Lord <allen@...> wrote:
|
|
That's interesting Bob.? I never really considered that some antenna geometry could impact impedance more than pattern, or vice-versa. Do you know of any open-source 3d em antenna simulators?? Would be interesting to create an antenna (and whatever groundplane mounts it) in solidworks or solvespace or such, and import into an em solver to see patterns at various freqs -- if something like that is feasible. thx, gil ----- Original message ----- From: Robert Bruninga <bruninga@...> Subject: Re: [TinyTrak] MTT4BT Installation on ATV/Motorcycle - Antenna Pattern Date: Saturday, September 18, 2021 12:43 PM FYI, Everyone has seen the full spherical radiation pattern of a dipole and the hemisphere pattern of a 1/4 wave over groundplane with an additional 3 dB gain? Bit it is not valid in most cases. No matter how you mount the antenna to its "ground plane" it will? not have a hemisphere pattern unless the ground plane is an INFINITE sheet of metal in all directions.? Similarly it wont have the added 3 dB gain either. The radials or metal of the small vehicle will in fact, lend to a match to the coax, but it does little to the antenna pattern.? At any distance from a raised radial ground plane antenna, it will still be an omni pattern.? The radials, etc only help provide a match.? Of course on a car or s omethign approaching the size of a wavelength, then there will be a pattern developed.? But not due to radials on a raised "ground plane" antenna. Just sayin. Bob,wb4apr On Sat, Sep 18, 2021 at 11:23 AM Allen Lord <allen@...> wrote: > > Do you mean a 1/4 whip with four or more 45 degree radiators when you refer to a "Ground Plane" antenna? Or a quarter wave whip mounted to the bike's chassis? > > 73, > > Allen AF6OF > > On Fri, Sep 17, 2021 at 6:57 PM <toy4trax@...> wrote: >> >> Allen, >> >> I'd have the MTT4BT in a pelican type case, similar to the AIO. If the AIO would have been transmit and receive, GSA, GSV, that would have been a good combo... but alas, no. >> >> Anyway, my goal was to take the GSA, GSV to/from my Garmin for GPS and display of the APRS waypoints. All this works on the bench. >> So, MTT4BT in pelican case, bulkhead connectors out to Power/data, antenna. >> >> Got the 8 watt so the ground-plane would not be an issue on an ATV/Moto(?). Maybe I'm wrong with this? > >? |
|
Sure,
toggle quoted message
Show quoted text
The program EZNEC is a great way to see antenna patgterns. The free version lets you build antenna (and strucgture) models of up to 500 pointe. I cannot live without it! Bob On Sat, Sep 18, 2021 at 6:24 PM Gil Smith <tinytrak@...> wrote:
|
|
Will this handle the modeling of adjacent antennae in the near field?
73,
Allen AF6OF -----Original Message-----
From: Robert Bruninga <bruninga@...> To: [email protected] Sent: Sat, Sep 18, 2021 7:35 pm Subject: Re: [TinyTrak] MTT4BT Installation on ATV/Motorcycle - Antenna Pattern Sure,
The program EZNEC is a great way to see antenna patgterns. The free version lets you build antenna (and strucgture) models of up to 500 pointe.? I cannot live without it! Bob On Sat, Sep 18, 2021 at 6:24 PM Gil Smith <tinytrak@...> wrote: > > That's interesting Bob.? I never really considered that some antenna geometry could impact impedance more than pattern, or vice-versa. > > Do you know of any open-source 3d em antenna simulators?? Would be interesting to create an antenna (and whatever groundplane mounts it) in solidworks or solvespace or such, and import into an em solver to see patterns at various freqs -- if something like that is feasible. > > thx, gil > > ----- Original message ----- > From: Robert Bruninga <bruninga@...> > To: [email protected] > Subject: Re: [TinyTrak] MTT4BT Installation on ATV/Motorcycle - Antenna Pattern > Date: Saturday, September 18, 2021 12:43 PM > > FYI, Everyone has seen the full spherical radiation pattern of a dipole and the > hemisphere pattern of a 1/4 wave over groundplane with an additional 3 dB > gain? Bit it is not valid in most cases. > > No matter how you mount the antenna to its "ground plane" it will? not > have a hemisphere pattern unless the ground plane is an INFINITE sheet > of metal in all directions.? Similarly it wont have the added 3 dB > gain either. > > The radials or metal of the small vehicle will in fact, lend to a > match to the coax, but it does little to the antenna pattern.? At any > distance from a raised radial ground plane antenna, it will still be > an omni pattern.? The radials, etc only help provide a match.? Of > course on a car or s omethign approaching the size of a wavelength, > then there will be a pattern developed.? But not due to radials on a > raised "ground plane" antenna. > > Just sayin. > Bob,wb4apr > > On Sat, Sep 18, 2021 at 11:23 AM Allen Lord <allen@...> wrote: > > > > Do you mean a 1/4 whip with four or more 45 degree radiators when you refer to a "Ground Plane" antenna? Or a quarter wave whip mounted to the bike's chassis? > > > > 73, > > > > Allen AF6OF > > > > On Fri, Sep 17, 2021 at 6:57 PM <toy4trax@...> wrote: > >> > >> Allen, > >> > >> I'd have the MTT4BT in a pelican type case, similar to the AIO. If the AIO would have been transmit and receive, GSA, GSV, that would have been a good combo... but alas, no. > >> > >> Anyway, my goal was to take the GSA, GSV to/from my Garmin for GPS and display of the APRS waypoints. All this works on the bench. > >> So, MTT4BT in pelican case, bulkhead connectors out to Power/data, antenna. > >> > >> Got the 8 watt so the ground-plane would not be an issue on an ATV/Moto(?). Maybe I'm wrong with this? > > > > > > > > > > > > |
|
Bob: That eznec looks interesting, and apparently the pro version is going to be free at the turn of the year when the author retires (though no passing off of source, so this program will eventually die off as future winblows versions break it). I just got?the current free/limited version to play with -- a new thing on my to-do list! thx, gil ----- Original message ----- From: Robert Bruninga <bruninga@...> Subject: Re: [TinyTrak] MTT4BT Installation on ATV/Motorcycle - Antenna Pattern Date: Saturday, September 18, 2021 7:35 PM Sure, The program EZNEC is a great way to see antenna patgterns. The free version lets you build antenna (and strucgture) models of up to 500 pointe.? I cannot live without it! Bob On Sat, Sep 18, 2021 at 6:24 PM Gil Smith <tinytrak@...> wrote: > > That's interesting Bob.? I never really considered that some antenna geometry could impact impedance more than pattern, or vice-versa. > > Do you know of any open-source 3d em antenna simulators?? Would be interesting to create an antenna (and whatever groundplane mounts it) in solidworks or solvespace or such, and import into an em solver to see patterns at various freqs -- if something like that is feasible. > > thx, gil > > ----- Original message ----- > From: Robert Bruninga <bruninga@...> > To:?[email protected] > Subject: Re: [TinyTrak] MTT4BT Installation on ATV/Motorcycle - Antenna Pattern > Date: Saturday, September 18, 2021 12:43 PM > > FYI, Everyone has seen the full spherical radiation pattern of a dipole and the > hemisphere pattern of a 1/4 wave over groundplane with an additional 3 dB > gain? Bit it is not valid in most cases. > > No matter how you mount the antenna to its "ground plane" it will? not > have a hemisphere pattern unless the ground plane is an INFINITE sheet > of metal in all directions.? Similarly it wont have the added 3 dB > gain either. > > The radials or metal of the small vehicle will in fact, lend to a > match to the coax, but it does little to the antenna pattern.? At any > distance from a raised radial ground plane antenna, it will still be > an omni pattern.? The radials, etc only help provide a match.? Of > course on a car or s omethign approaching the size of a wavelength, > then there will be a pattern developed.? But not due to radials on a > raised "ground plane" antenna. > > Just sayin. > Bob,wb4apr > > On Sat, Sep 18, 2021 at 11:23 AM Allen Lord <allen@...> wrote: > > > > Do you mean a 1/4 whip with four or more 45 degree radiators when you refer to a "Ground Plane" antenna? Or a quarter wave whip mounted to the bike's chassis? > > > > 73, > > > > Allen AF6OF > > > > On Fri, Sep 17, 2021 at 6:57 PM <toy4trax@...> wrote: > >> > >> Allen, > >> > >> I'd have the MTT4BT in a pelican type case, similar to the AIO. If the AIO would have been transmit and receive, GSA, GSV, that would have been a good combo... but alas, no. > >> > >> Anyway, my goal was to take the GSA, GSV to/from my Garmin for GPS and display of the APRS waypoints. All this works on the bench. > >> So, MTT4BT in pelican case, bulkhead connectors out to Power/data, antenna. > >> > >> Got the 8 watt so the ground-plane would not be an issue on an ATV/Moto(?). Maybe I'm wrong with this? > > > > > > > > > > > >? |
|
The Isotropic antenna can be found on any street in Utopia.:) Allen? On Sat, Sep 18, 2021 at 12:43 PM Robert Bruninga <bruninga@...> wrote: FYI, Everyone has seen the full spherical radiation pattern of a dipole and the |
to navigate to use esc to dismiss