LowBand station antenna options

[DisasterGuy]

Thanks all. No, I don't need more than 25khz of bandwidth. These will be for dedicated channels. I don't mind spending money (up to a few thousand per antenna) as this is a public safety applications and just hanging the antennas or replacing them costs several thousand dollars.

 

[W8UU]

Hard to broadband a ground plane or Ringo but not bicone or some of the other military designs.

Broadbanding bicones and military antennas is techno-geekery stuff. If you're in to that -- knock yourself out. I wouldn't have the time or knowledge to delve into such a project. I'd just buy something I know would work, install it, make sure the system performs as it should, then be done. On to other things.

 

[prcguy]

Broadbanding bicones and military antennas is techno-geekery stuff. If you're in to that -- knock yourself out. I wouldn't have the time or knowledge to delve into such a project. I'd just buy something I know would work, install it, make sure the system performs as it should, then be done. On to other things.

The eBay link I provided to the military bicone hub is already figured out, just add 8ft aluminum elements and it will work as intended 30 to 90MHz

 

[RFI-EMI-GUY]

The eBay link I provided to the military bicone hub is already figured out, just add 8ft aluminum elements and it will work as intended 30 to 90MHz

How do you dress the feedline as not to unbalance the antenna pattern and VSWR?

 

[prcguy]

How do you dress the feedline as not to unbalance the antenna pattern and VSWR?

The OE-254 bicone has an insulated mast section so its isolated from a metal mast and it attaches with a common large size threaded bolt. I made a mast adapter for mine using a bolt cast in resin inside a length of military mast. The internal balun provides some common mode suppression.

 

[RFI-EMI-GUY]

The OE-254 bicone has an insulated mast section so its isolated from a metal mast and it attaches with a common large size threaded bolt. I made a mast adapter for mine using a bolt cast in resin inside a length of military mast. The internal balun provides some common mode suppression.

I should maybe break up the feedline with clamp on chokes at < 1/4 wave sections?

 

[prcguy]

I should maybe break up the feedline with clamp on chokes at < 1/4 wave sections?

If your using an actual OE-254 hub/balun then I don't see any need for chokes except for peace of mind, these have been used all over the world with no reported problems.

 

[RFI-EMI-GUY]

If your using an actual OE-254 hub/balun then I don't see any need for chokes except for peace of mind, these have been used all over the world with no reported problems.

My thought was to break up the feedline resonance as it will be in near field of lower elements.

 

[petnrdx]

I love Telewave. And even a single bay LB dipole is more omni than you might expect. BUT, the Telewave antenna is HUGE at
50 mhz. You get down to 45 and 39 Mhz they are gigantic. Same with the DB212. EXCELLENT antennas. For ease of installation it's
difficult to beat the Kreco. Off the top of my head the standoff for the Telewave is going to be 8 ft or more, and the pipe is around
5 inch diameter. They really perform, but the bending moment on those is SIGNIFICANT. In my experience, the Kreco's exhibit a bit of "uptilt" compared to the folded dipole. One thing is certain, the Telewave is HEAVY, tough and you would only have to buy it once. The Kreco is also pretty tough. We had at least one of each (DB, Telewave and Kreco's) many thousands of feet up in Nevada. They all work pretty well.

 

[prcguy]

I love Telewave. And even a single bay LB dipole is more omni than you might expect. BUT, the Telewave antenna is HUGE at
50 mhz. You get down to 45 and 39 Mhz they are gigantic. Same with the DB212. EXCELLENT antennas. For ease of installation it's
difficult to beat the Kreco. Off the top of my head the standoff for the Telewave is going to be 8 ft or more, and the pipe is around
5 inch diameter. They really perform, but the bending moment on those is SIGNIFICANT. In my experience, the Kreco's exhibit a bit of "uptilt" compared to the folded dipole. One thing is certain, the Telewave is HEAVY, tough and you would only have to buy it once. The Kreco is also pretty tough. We had at least one of each (DB, Telewave and Kreco's) many thousands of feet up in Nevada. They all work pretty well.

What type of Kreco antenna are you referring to? They make coaxial dipoles both regular and folded top element. The folded version is wider band but still very narrow like 2Mhz or less at VHF lo. They also make VHF lo discones, that is what you want for full band.

 

[petnrdx]

Since he said he was talking two separate antennas, I was referring their "co-axial" designs.
I like the CO-41 type better, but the CO-30 performs well also.
The CO-41 is at ground potential.
I have used all of their co-axial and co-plane antennas.
Not broad band tho.
Found them all to be pretty good, and way less expensive to get purchased AND installed.
Like I said previously, I think the Telewave folded dipole out performs, but they are HUGE and put a lot of load and twist on a tower.
In addition to the cost of purchase and shipping.

 

[prcguy]

Since he said he was talking two separate antennas, I was referring their "co-axial" designs.
I like the CO-41 type better, but the CO-30 performs well also.
The CO-41 is at ground potential.
I have used all of their co-axial and co-plane antennas.
Not broad band tho.
Found them all to be pretty good, and way less expensive to get purchased AND installed.
Like I said previously, I think the Telewave folded dipole out performs, but they are HUGE and put a lot of load and twist on a tower.
In addition to the cost of purchase and shippi

Ive got most of the Kreco line and their coaxials are an industry standard. Childs Antennas also makes VHF lo coaxial antennas and they cost less than Keco. The folded dipoles mount up against a mast or tower making them into a 2 element beam with some gain. I've never seen a folded dipole stuck up in the air without a reflector mast so you can't really compare them to a coaxial dipole which will have less gain unless mounted the same distance out from a mast or tower as a folded dipole. A folded dipole would also be directional where a coaxial in the clear will be omni.

 

[nokones]

My drive to work takes me past our local CHP office, and they are running a dipole off the side of their tower.

More than likely that antenna would be a 39 MHz tuned antenna and most likely being used in Southern California in San Diego, Orange, Riverside, and San Bernardino Counties.

 

[mmckenna]

More than likely that antenna would be a 39 MHz tuned antenna and most likely being used in Southern California in San Diego, Orange, Riverside, and San Bernardino Counties.

Might be, but I'm not in Southern California.

 

[prcguy]

I just put up a VHF lo band antenna for CHP on a roof using an actual surplus CHP wide band whip. I made a bracket with NMO mount and four thin wire radials and roof mounted it in an HOA sensitive area, then painted it to match the surroundings. This CHP antenna runs to a diplexer and is combined with the cammo Discone to the left. It works very well and has a great match across the 39-46MHz range.

 

[jeepsandradios]

Anyone know where to find a price catlog on the Kreco stuff. Ive found nothing anywhere. I' think the GP-125 is like the old ASP antenna that was discontinued and would like to try one.

 

[prcguy]

Anyone know where to find a price catlog on the Kreco stuff. Ive found nothing anywhere. I' think the GP-125 is like the old ASP antenna that was discontinued and would like to try one.

I think you have to call them or they have an eBay outlet with some models like this one.

Kreco D-150A Broadband Discone Base Antenna 150-1200MHz | eBay

Kreco Antennas. 500 Watt Maximum Transmit Power. Your choice of UHF Female connector (D-150A model) or N Female connector (D-150AN model).

www.ebay.com

 

[DisasterGuy]

Thanks all. I was able to find that Sinclair has the DB201 style design still in production for low band as the SG101-SF1PASNM and was able to get a few of them ordered. TESSCO price was fairly reasonable at about $1200/ea