VHF antenna suggestions for commercial repeater…

[BMDaug]

So I am getting closer to installing my repeater. I’m working with WIA to modify my license to allow for repeater and base station operation, I pick up a four cavity duplexer tomorrow morning, and the Tait TB9100 is about to go out for an in-band alignment! All I need is an intermod panel, feed line and an antenna… It’ll need to cover from about 150MHz to 170MHz.

So… does anyone have any good recommendations for antennas? There are some used Telewave ANT150Ds around, but is a single folded dipole good for my situation? The site I’m looking at is at 11k ft. and the valley floor is at 7800 ft. I need to cover the peak above the site, which is at 14k ft. and all the way to the valley below. I also need to attempt to cover some parts of the mountain that are over a ridge adjacent to the site. The site is quite large, with five or six towers and as many buildings. Several of the towers are devoted to microwave/cellular, and there is a linked UHF ham repeater up there with fantastic coverage…

Also, what tools are best for generating coverage maps? That may help me narrow my search and explore options.

Thanks for reading and any help is appreciated. This will be my first solo repeater install, so I’m feeling a bit overwhelmed!

Regards,
Brian

 

[nd5y]

Also, what tools are best for generating coverage maps? That may help me narrow my search and explore options.

If you want best you need to spend a lot of money on expensive software or a consultant.
These are free.

Radio Mobile WEB Site

www.ve2dbe.com

SPLAT! A Terrestrial RF Path Analysis Application For Linux/Unix

 

[KM4OKT]

How far away is the valley? Too much gain and you'll shoot over top of it with most of your gain. Unity gain would work better for trying to cover up to the peak because of the vertical beamwidth being so wide. Not very keen on using any CommScope antennas anymore since they done away with all the enclosed phasing harness antennas.

 

[BMDaug]

If you want best you need to spend a lot of money on expensive software or a consultant.
These are free.

Radio Mobile WEB Site

www.ve2dbe.com

SPLAT! A Terrestrial RF Path Analysis Application For Linux/Unix

Wow! Thanks. I can’t put in my exact frequencies since the tool is for amateur use, but I can get pretty close. Perhaps a big Omni is what I need. The PA is 100W, so I should be able to overcome feed line losses and still get 45+dB out of the system.

@KM4OKT it’s pretty steep down to the valley. Here’s my first coverage map with an Omni antenna, 2dB gain, 3dB losses @ 50W… This would be excellent for me. Aside from using this for business purposes, it’ll be an auxiliary SAR repeater. It’s dual mode. I operate AES encrypted P25C and SAR will be FMN.

-B

 

[KM4OKT]

From looking at that, your Telewave would probably do just fine. It would be near omni-directional depending on the spacing from mast of the antenna.

 

[BMDaug]

So does anyone know what an EP at the end of the model number means on a Telewave ANT150D(-EP)? I’ve searched around Telewave.com and the internet in general and I can’t find any mention of it online. I’ve seen @mmckenna and some others talk about this antenna before. Anyone familiar?

Thanks,
Brian

 

[KM4OKT]

Elliptical maybe? All mine are ANT150D with no EP on the end. I would be curious to know that as well.

 

[BMDaug]

Elliptical maybe? All mine are ANT150D with no EP on the end. I would be curious to know that as well.

Ya… still searching!

 

[mmckenna]

So does anyone know what an EP at the end of the model number means on a Telewave ANT150D(-EP)? I’ve searched around Telewave.com and the internet in general and I can’t find any mention of it online. I’ve seen @mmckenna and some others talk about this antenna before. Anyone familiar?

Thanks,
Brian

I don't know. I looked at the Telewave stuff I had on my computer, but didn't come up with anything. You can give them a call on Tuesday.

Years ago I think I was in that area. If I am remembering correctly, it looks like you've got pretty good coverage from that site. Just be aware, those free tools are not very granular. You'd need to get the higher end software with high resolution ground clutter files to give you really accurate coverage maps. But, I suspect for what you are doing, it's still pretty accurate.

I've got a few sites that are similar in elevation difference ~3k feet from antenna down to sea level in about 3/4 of a mile. Higher gain antennas blew right over the heads of the users and the site wasn't really that useable until you got several miles away. I replaced the 6dB gain vertical with a single ANT-450D and added some 'mechanical downtilt' by adding a 10 foot length of rigid conduit and some Unistrut to hold the antenna at about a 20º angle. It brought all the coverage in where it was needed.

It’ll need to cover from about 150MHz to 170MHz.

The antenna should cover that OK, but the duplexer isn't.


If you are doing the install yourself, pay close attention to the installation guide. Anti-seize compound on the mounting bolts if you ever want to take it apart. Telewave has an excellent guide on how to waterproof the coax connectors.

https://www.telewave.com/wp-content/uploads/2016/12/TWDS-0502.pdf

Should be a good setup. Mine is in a location where it can see hurricane force winds in the winter, and it's done just fine. I've seen a few of these coated in quite a bit of ice, also.

 

[BMDaug]

I don't know. I looked at the Telewave stuff I had on my computer, but didn't come up with anything. You can give them a call on Tuesday.

Years ago I think I was in that area. If I am remembering correctly, it looks like you've got pretty good coverage from that site. Just be aware, those free tools are not very granular. You'd need to get the higher end software with high resolution ground clutter files to give you really accurate coverage maps. But, I suspect for what you are doing, it's still pretty accurate.

I've got a few sites that are similar in elevation difference ~3k feet from antenna down to sea level in about 3/4 of a mile. Higher gain antennas blew right over the heads of the users and the site wasn't really that useable until you got several miles away. I replaced the 6dB gain vertical with a single ANT-450D and added some 'mechanical downtilt' by adding a 10 foot length of rigid conduit and some Unistrut to hold the antenna at about a 20º angle. It brought all the coverage in where it was needed.



The antenna should cover that OK, but the duplexer isn't.


If you are doing the install yourself, pay close attention to the installation guide. Anti-seize compound on the mounting bolts if you ever want to take it apart. Telewave has an excellent guide on how to waterproof the coax connectors.

https://www.telewave.com/wp-content/uploads/2016/12/TWDS-0502.pdf

Should be a good setup. Mine is in a location where it can see hurricane force winds in the winter, and it's done just fine. I've seen a few of these coated in quite a bit of ice, also.

Thanks for all the info… That backwards tape thing is interesting and I’ve never heard of Scotch-Kote!

As far as the 150-170 thing… that’s not the working range of the actual system. I just haven’t figured out if I’m going to modify the station class and change the location of my existing VHF license, or add a second pair of frequencies to my license with necessary emissions designators and station classes for repeater and base operations. I just threw a range out there. Right now, my VHF channels are 152.915 and 159.960 and those may wind up as my repeater pair, it’ll just depend on what’s cheaper and/or easier to license properly.

-B

 

[mmckenna]

Thanks for all the info… That backwards tape thing is interesting and I’ve never heard of Scotch-Kote!

Hard to get in some locations. The vapors off it will pretty much give you a buzz. It does work well, though.

 

[BMDaug]

Hard to get in some locations. The vapors off it will pretty much give you a buzz. It does work well, though.

Hahaha alright then! That’s great when you are about to climb a tower!!

So I picked up the duplexer. Sinclair Radio Laboratories four cavity. I didn’t realize the thing was in a metal box. It’s the size of a small fridge! Should work well though. Not sure what coax they are running between the cans, but it’s about 1/2” diameter. Looks like it’ll be great, but I hope there is space in the shack and the owner doesn’t charge me an extra couple hundred a month just for the space…

-B