NE Florida Base Station - Attic Setup - Advice

[WSKF472]

Good Evening, GMRS newby here.

I am sure there is already a post somewhere within this group, however for brevity i figured i would start an additional post.

I have recently procured a 50W mobile with a 13Amp power supply and am attempting to figure out the best antenna solution for an attic antenna solution.

Live in a HOA so exterior solutions are out.

Ive read a bunch regarding J-Poles / Di Poles etc.., still a bit in the weeds.

I live in a single story house, attic height is about 20-25' to the rafters.

I am looking for general recommendations advice, on where to start.

Thank you for your time and comments.

WSKF472

[WRYZ926]

You are going to want a vertically polarized antenna for GMRS so that rules out a dipole.

How tall is your attic?  

Is there a bunch of electrical wires, metal duct work, or other metal objects in the attic?

Knowing that will help us recommend an antenna for you.

[WSKF472]

16 hours ago, WRYZ926 said:

You are going to want a vertically polarized antenna for GMRS so that rules out a dipole.

How tall is your attic?  

Is there a bunch of electrical wires, metal duct work, or other metal objects in the attic?

Knowing that will help us recommend an antenna for you.

Thank you for your support, and prompt reply.

 

Attic is 5' tall, surrounded by this solar board and 2x4's.  No other metal other than the alluminum gutters on the Left Hand / Right Hand Side of the roofing.

Looks like one 110 power cable running down the left hand side.

Thank you for your advice.

WSKF472

[SteveShannon]

Is the solarboard only on the gable ends, not between the rafters?

[WRYZ926]

3 minutes ago, SteveShannon said:

Is the solarboard only on the gable ends, not between the rafters?

It looks like it is between the rafters too. Or something shiny and metallic is there.

@WSKF472 that solar board is going to cause nothing but issues with trying to receive and transmit with any antenna placed in the attic.

Now as far as the 5 foot attic height, the Comet CA-GMRS antenna will fit as it is only 42 inches tall.

[WRTC928]

I'm using a Diamond SG7900 dual-band antenna under the roof of my deck as a "stormy weather" antenna (long story). If your attic is a few inches higher than 5', it should fit as it's 62" tall. I've mounted it permanently now, but for a long time, I ran it on a mag mount and 16" pizza plate. One of the nice things about it is that it doesn't need much ground plane to work well. It claims 7.6 dBi (5.45 dBd) gain on  UHF and I can tell you it really blasts out a signal. Additionally, if you decide to get an amateur radio license at some point in the future, you don't need another antenna to add 2 meters and 70 centimeters. It's worth a look if you have room. 

[WRUE951]

i would just mount a J-Pole on the outside toward the back and wait for a complaint from the HOA..  Worst thing they can do is tell you NO, then at that time work on concealing in your attic..   Sometimes you just got to be a Rebel  (As Steve would call it)  +

[WRYT601]

Some hams use slot antennas, horizontal slots cut into old satellite dishes that serve as vertical antennas.  UHF is short enough of a wavelength to hide an antenna anywhere.  Even an existing roof vent pipe or a fake lightning rod can be used as an antenna.  If you have a nanoVNA, your options are limitless.

I would just build a yagi and stick it up on a 20' pole because they cannot stop you from having a TV antenna.  GMRS and much of the OTA television nowadays is UHF, so who are they to say its not for TV? There is a high probability you could receive a TV station on it (HOA = in a town close to a station or translator) and there is no law that says you gotta turn it horizontal.  

[WSFB377]

What is your objective? While I want to get an antenna in my attic eventually, right now I am able to hit a couple repeaters with a mag mount/pizza pan on top of a shelf on low power. 

Are you in range of the MetroJax 675 or Durbin 575 repeaters? You may want to check out this Facebook group https://www.facebook.com/share/g/17L9UAEXbr/

 

[WSKF472]

7 hours ago, WSFB377 said:

What is your objective? While I want to get an antenna in my attic eventually, right now I am able to hit a couple repeaters with a mag mount/pizza pan on top of a shelf on low power. 

Are you in range of the MetroJax 675 or Durbin 575 repeaters? You may want to check out this Facebook group https://www.facebook.com/share/g/17L9UAEXbr/

 

Thank you for the response.  Unfortunately, im on the south side of Saint Augustine, the closest repeater i have to me is palatka and green cove springs.

 

High level wants is to be able to communicate with my elderly parents ~8 miles out, and learn more about this hobby to eventually get my technician licence and have my wife be able to get ahold of me in my truck while im mobile around the city.

 

I have a mobile antenna currently and will be testing a similar setup to test range of simplex within the attic.

 

I will update this post when i make some purchases.

[WSKF472]

Thank you everyone for the advice and suggestions.  I really do appreciate the community outreach.

Ok.  So current plan is to investigate the following antennas: Comet CA-GMRS and Diamond SG7900.

Plan on testing some handhelds that i have on simplex to gauge interference of the solar board at some known distance intervals.

Finally to quote WRUE951 it might be time to rebel a bit, i will investigate some external ideas, might be time to run for the HOA board.

A follow up question regarding "External Antennas" i live in a thunderstorm prone area, is there some sort of documentation regarding lightning grounding some one could advise on.

The wife is very supportive of my new found hobby but dosnt want the house struck..

I will update this post with follow up pictures and results of testing, thank you again everyone for the advice and council.

WSKF472

 

[WRYZ926]

Here is a good article that is simple to understand about proper grounding.

https://reeve.com/Documents/Articles Papers/Reeve_AntennaSystemGroundingRequirements.pdf

Yes you want all coax cables grounded with lightning arrestors right before they enter the structure. You will also want any and all antennas, masts, towers, etc all properly grounded. And you want all grounds to be connected to your home's service ground, also known and bonded.

[WRUE951]

22 hours ago, WRYT601 said:

Some hams use slot antennas, horizontal slots cut into old satellite dishes that serve as vertical antennas.  UHF is short enough of a wavelength to hide an antenna anywhere.  Even an existing roof vent pipe or a fake lightning rod can be used as an antenna.  If you have a nanoVNA, your options are limitless.

I would just build a yagi and stick it up on a 20' pole because they cannot stop you from having a TV antenna.  GMRS and much of the OTA television nowadays is UHF, so who are they to say its not for TV? There is a high probability you could receive a TV station on it (HOA = in a town close to a station or translator) and there is no law that says you gotta turn it horizontal.  

they are popular for 900Mhz..   not sure how well they would work in UHF

 

[WRUE951]

3 hours ago, WSKF472 said:

Thank you everyone for the advice and suggestions.  I really do appreciate the community outreach.

Ok.  So current plan is to investigate the following antennas: Comet CA-GMRS and Diamond SG7900.

Plan on testing some handhelds that i have on simplex to gauge interference of the solar board at some known distance intervals.

Finally to quote WRUE951 it might be time to rebel a bit, i will investigate some external ideas, might be time to run for the HOA board.

A follow up question regarding "External Antennas" i live in a thunderstorm prone area, is there some sort of documentation regarding lightning grounding some one could advise on.

The wife is very supportive of my new found hobby but dosnt want the house struck..

I will update this post with follow up pictures and results of testing, thank you again everyone for the advice and council.

WSKF472

 

Some folks will tell you that don't need to ground a J-Pole Antenna.. While that is mostly true, grounding or not ground  a J-Pole does not effect it's performance..  However, you still need to ground the mast the j-pole is attached to,  if using one.  Most defiantly mount a lightning arrestor at the point where the cable enters your house/building..  If you use a Cooper J-pole, I would ground it, if using an Ed Fong type J-Pole mounted to an eve and not mounted to a metal mast, than you don't need to ground..  But in any case you still want the lightning arrestor.  

[WRYT601]

14 minutes ago, WRUE951 said:

they are popular for 900Mhz..   not sure how well they would work in UHF

 

They work all the way down to HF. 

[WRUE951]

1 minute ago, WRYT601 said:

They work all the way down to HF. 

they may work below VHF,,   but.  ......    ..    

[WRYT601]

4 hours ago, WRUE951 said:

they may work below VHF,,   but.  ......   

Shunt feed a horizontal folded dipole and it becomes a vertically polarized slot antenna. 

I am beginning to notice a pessimistic naysayer-like attitude and a general lack of interest in actual experimentation among many GMRS users. 

At 900MHz, slot antennas are merely a convenient method of building an antenna, even more convenient in the GHz where wave guides can be used to feed them, but convenience at microwave frequencies doesn't mean impractical at lower frequencies.

[WRYT601]

Slot antenna on a Puffs box.  Imagine all the places this could be stuck to and painted over.  

Well below 2:1 SWR on 462-468MHz

For GMRS, start with a slot 1/8" wide and as long as most dipole calculators suggest (I used 1 foot), then, with the VNA span set to 430MHz to 470MHz, find the feed point where the SWR dips down the lowest by sliding the connector along the slot (ignoring what frequency that dip is on), solder it down, then shorten the other end of the slot with a shorting strap to bring the dip up to 465MHz.

[WRUE951]

10 hours ago, WRYT601 said:

Shunt feed a horizontal folded dipole and it becomes a vertically polarized slot antenna. 

I am beginning to notice a pessimistic naysayer-like attitude and a general lack of interest in actual experimentation among many GMRS users. 

At 900MHz, slot antennas are merely a convenient method of building an antenna, even more convenient in the GHz where wave guides can be used to feed them, but convenience at microwave frequencies doesn't mean impractical at lower frequencies.

Now, Now.....   I've built several antennas. Some work great and some are somewhere mixed in a Budweiser beer can..  Usually when i spend time building an antenna, the time spent is to get some pretty decent results and for an application i need.  I no longer use HF in my home, but occasionally in my Truck..  I have no need for a HF antenna..  I'm not arguing that the slot antenna will not work in HF, but i may raise some points in how well it works..  An old school science teacher once showed us how to get great SWR results in HF with a coat hanger and at the same time proved how bad it performed..   Just saying there fella  - Nothing to do with Naysaying or being pessimistic, just using my time in a productive manor.   Now if your are learning, that's great and that's productive..  Carry on

[WRYT601]

1 hour ago, WRUE951 said:

Now, Now.....   I've built several antennas. Some work great and some are somewhere mixed in a Budweiser beer can..  Usually when i spend time building an antenna, the time spent is to get some pretty decent results and for an application i need.  I no longer use HF in my home, but occasionally in my Truck..  I have no need for a HF antenna..  I'm not arguing that the slot antenna will not work in HF, but i may raise some points in how well it works..  An old school science teacher once showed us how to get great SWR results in HF with a coat hanger and at the same time proved how bad it performed..   Just saying there fella  - Nothing to do with Naysaying or being pessimistic, just using my time in a productive manor.   Now if your are learning, that's great and that's productive..  Carry on

Agreed, at HF, questionable performance can be expected, but at UHF, it is quite practical especially for someone needing to hide their antennas.  Recall that this thread started out with discussion of an antenna being put inside of a faraday cage, so yea...

[Lscott]

11 hours ago, WRYT601 said:

Slot antenna on a Puffs box.  Imagine all the places this could be stuck to and painted over.  

Well below 2:1 SWR on 462-468MHz

For GMRS, start with a slot 1/8" wide and as long as most dipole calculators suggest (I used 1 foot), then, with the VNA span set to 430MHz to 470MHz, find the feed point where the SWR dips down the lowest by sliding the connector along the slot (ignoring what frequency that dip is on), solder it down, then shorten the other end of the slot with a shorting strap to bring the dip up to 465MHz.

That's some nice work. You don't see much in the way of people building slot antennas.

You likely could stick some copper foil tape on a window in place of the box. 

[WRYT601]

A regular dipole could be made with foil tape and put in a window just the same, it doesn't have to be a slot.  One of the reasons I initially brought up slot antennas was because of that foil solarboard.  I would probably slice a slot into that foil, reinforce it with copper tape, and then connect my coax directly to the solarboard slot on the gable end.  It is worth a try (if that direction is ok) and it costs essentially nothing.  

Edit: the foil is likely on both sides, so thats the only tricky part.  If the slot is cut through both without damaging the plywood, I imagine the back slot would easily couple to the driven slot on the inside.  

[MDYoungblood]

Luckily I don't have to worry about an HOA.

I built one out of a short length of 450ohm ladder line, did all the measurements, a 4ft length of 1 1/4" PVC, about 40ft of RG8X, a SO-239 panel mount connector and 2 PL-259.

I made the ladder line into a Slim Jim antenna, fastened it to a pipe cap with a tie strap at the top of the pipe,sealed the cap with non corrosive silicone sealed, a short length of coax to the connector and created a choke with about a foot of coax at the bottom, soldered to the panel connector (used the type that goes in a 3/4"hole and has 2 nuts, not the square flange type). Cost me only for the pipe caps, had the rest.

SWR on my NanoVNA read 1.2 in the center of the band and 1.9 on the fringes. I got 2 long U-Bolts and attached it to one of the vent pipes on my roof. 

My next project is a collinear ground plane but the "Honey Do List"  comes first.