Indoor antennas?!

[priller]

Hey folks!

Trying to figure out best option for indoor GMRS antenna.  Initially unimpressed by some cheap 70cm whips on mag mount (not specifically tuned for 462-467) Put them in window sill on cookie sheet, and barely any improvement over standard whip antenna on HT. 

Anyone out there running indoor GMRS antenna to HT or base station?

Would one of the tuned fiberglass antennas on Amazon be effective from indoors?

 

thanks all!

[kidphc]

Hey folks!
Trying to figure out best option for indoor GMRS antenna.  Initially unimpressed by some cheap 70cm whips on mag mount (not specifically tuned for 462-467) Put them in window sill on cookie sheet, and barely any improvement over standard whip antenna on HT. 
Anyone out there running indoor GMRS antenna to HT or base station?
Would one of the tuned fiberglass antennas on Amazon be effective from indoors?
 
thanks all!

I use external antennas mainly when I can for hf. For the ham uhf/vhf stuff it's in the attic. Fortunately, I have almost 10 feet in height to work with. So up went a 8ft long fiberglass vertical. All this because of the HOA.

More inline to answer your question, I made an indoor blade antenna. I took a N9Tax slim jim tuned for gmrs, only because I got lazy. I ran inside some plastic wiring track up to the 2nd floor in a vaulted area of my house. Marginal success with both the wife and ht. It started to shine when I hooked up a db-20g/at-779uv to it.

The range from the ht went from 600ft to closer 1500-1700 ft on simplex at 20w. Keep in mind a moderately Heavily wooded suburban area.

It was enough for my wife to be able call me at a local Plaza while I was about 30ft inside a Walgreen, when I was on a ht.

As far as repeater work it was almost as good as being outside with the ht. But really that is how good the local gmrs repeaters around here are.

Sent from my SM-S901U using Tapatalk

[priller]

35 minutes ago, kidphc said:

I use external antennas mainly when I can for hf. For the ham uhf/vhf stuff it's in the attic. Fortunately, I have almost 10 feet in height to work with. So up went a 8ft long fiberglass vertical. All this because of the HOA.

More inline to answer your question, I made an indoor blade antenna. I took a N9Tax slim jim tuned for gmrs, only because I got lazy. I ran inside some plastic wiring track up to the 2nd floor in a vaulted area of my house. Marginal success with both the wife and ht. It started to shine when I hooked up a db-20g/at-779uv to it.

The range from the ht went from 600ft to closer 1500-1700 ft on simplex at 20w. Keep in mind a moderately Heavily wooded suburban area.

It was enough for my wife to be able call me at a local Plaza while I was about 30ft inside a Walgreen, when I was on a ht.

As far as repeater work it was almost as good as being outside with the ht. But really that is how good the local gmrs repeaters around here are.

Sent from my SM-S901U using Tapatalk

 

Thanks for the feedback!  I’m thinking the slimjim might be the ticket, I even have that same base station in play.

I have a lot to learn, do I need to ground the j-pole Or slim Jim?

 

[Socalgmrs]

Ok so first this is not going to net a load more.  Second if your mag mount antenna was not tuned for 462-467 then that’s most of your problem.  Line of sight is what you need.  That’s the reason an antenna up high gets results.  I guarantee if you could stand on your roof your hand held would get waaaay further.  What you need is hight and line of sight.  If you can’t get that then you’re playing a game of diminishing returns.   
you could take a 50w radio with a 12db gain yagi radiating almost 700 watts and put it indoors with other buildings around and maybe get a mile while a guy with a 5w HT with a 771 on the roof may get 30plus miles.  
 

[kidphc]

Socal is correct everything in everything he is saying.

Antennas will be much better when outside, when properly tuned for your service, have a proper ground plane (counterpoise), with the lowest loss coax for that frequency and high as you can get it. Then they will perform up 1000% better than the same setup on the ground.

VHF/UHF are line of sight for the most part. Get them up high, limit their obstructions and they start performing well. I had a buddy on a roof top (15 stories up) some 20 miles away he was able to hit me on simplex with 5w. We could do 15 miles of simplex with his base. But his antenna was over 100 feet up using air core hardline. RiP WRPJ758, 73. The old fart understood the basics.

When it comes down to it pretty much all antennas are a compromise to begin with. Make them smaller, shove them inside of house, put it on a ht, use a hi-gain antenna, etc and you are adding compromises on top of compromises.


Any reason you are trying to use indoor antennas? Just about everyone will recommend against it right away. Almost all my gmrs/ham gear is in the basement.

This blade antenna I built was for my wife to use on rare occasions. Really was onl built to cover the neighborhood to get in touch with the kid. We used it all night for Halloween.

For grounding, if everything is indoors than no you will not need grounding. If anything exits the house I recommend grounding. Even if is just the co-ax. You can get static buildup just from dust blowing over it in the wind.






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[SteveShannon]

Any antenna will perform better outdoors than that same antenna will perform indoors, unless the only people you want to communicate with are also inside the same building.

You have discovered that a small mobile whip antenna indoors functions almost exactly the same as the small portable whip antenna attached to your radio.  That’s right.  A whip antenna is a whip antenna. The only difference is that mobile ones are built in such a way that they can be mounted on the exterior of your car.  Being mounted externally is the part that enhances performance, not the construction of the antenna.  Moving it indoors cripples it.

Height and visibility are the two of the factors that benefit antennas the most.  Being designed with a more focused propagation pattern (gain) will also  help, but only if you have the visibility. You’ll hear it often here: line of sight is crucial.  UHF follows a straight path like light and like light It can reflect and refract. Moisture attenuates it. Metal in a building attenuates RF in general. Moisture bearing plants, clouds, even snow can weaken a UHF signal.

RF power makes little difference in range.

Gravity affects it, but because RF travels so fast, the effect of gravity is essentially nothing for short range. Your range might extend 5% further than the visible horizon.

[nokones]

11 hours ago, priller said:

Hey folks!

Trying to figure out best option for indoor GMRS antenna.  Initially unimpressed by some cheap 70cm whips on mag mount (not specifically tuned for 462-467) Put them in window sill on cookie sheet, and barely any improvement over standard whip antenna on HT. 

Anyone out there running indoor GMRS antenna to HT or base station?

Would one of the tuned fiberglass antennas on Amazon be effective from indoors?

 

thanks all!

I'm running a non-ground Laird mobile antenna tuned for 465 Mhz that I placed in my attic and ran a LMR400 cable approx. 32 feet to one of my base station radios. I can hit all the repeaters that are within range of my location.

 

[priller]

42 minutes ago, nokones said:

I'm running a non-ground Laird mobile antenna tuned for 465 Mhz that I placed in my attic and ran a LMR400 cable approx. 32 feet to one of my base station radios. I can hit all the repeaters that are within range of my location.

 

Very nice!  Yeah that might be an option for me too.  Thank you, second time I’ve heard of the Laird antennas.

[WRDU469]

For what it is worth, I use an Ed Fong antenna in my attic. Does very well. I was previously using a copper j-pole from KB9VBR Antenna's. Both work well and only a slight perceived difference in TX/RX range. I am getting a better SWR with the Ed Fong and continue to use that antenna. Here is a pic of that install.

 

 

[RayDiddio]

I made my own. It is compact, portable and I hang it outside my doorway during the day. It transmits well and receives very well. It was about $10 in parts and an hour of time between build and fine tuning it. Using two AWG 8 copper wires at 5.8" in length each for a total of 11.6 inches, some solder, some RG-8X and an electrical tee box that is weather proof at IP67.

I get between 1.1:1 - 1.3:1 SWR across the band with reflected power hitting at 0.05W at the highest. I used a NanoVNA to tune it. I have a ferrite choke on it near the feed for noise control. Big improvement over stick and rubber duck antennas that I own when using indoors, but that has a lot to do with it being outside. I live in a very low lying area that is prone to ponding during rainstorms as well as being surrounded by trees and buildings.