5/8th Wave VHF Low Band Antenna

[LongIslandHonker]

Do they exist? I've searched high & low for a commercial grade 5/8ths wave vertical coaxial dipole cut specifically for 33.4 MHz & 46.46 MHz & the only thing close to what I believed could be what I needed at the Antenna Farm was the $600+ Commander antenna, a quick e-mail to them was a curt: "I don't know". Now I've purchased from them before so I understand & fully accept the prevailing mindset, what I don't get is an e-mail with follow up phone queries to Commander went totally unanswered, can anybody possibly assist me in this? Thanks in advance for your time, patience & knowledge.









The Volunteer Concept

 

[cmdrwill]

Look for a 1/4 wave coaxial dipole, that was most popular many years ago.

Some of the "5/8" over ground-plane type antennas are not made anymore.

 

[Project25_MASTR]

What's the application?


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[prcguy]

One single 1/4 wave or 5/8 wave ground plane or coaxial will not cover both frequencies very well, your only going to get a few MHz BW before efficiency falls off. There are some military antennas that work well across that range and more if you can find them surplus, look for a COM201B ground plane.
prcguy

 

[cmdrwill]

One single 1/4 wave or 5/8 wave ground plane or coaxial will not cover both frequencies very well, your only going to get a few MHz BW before efficiency falls off.
prcguy

Very good point Sir. Even a quarter of a mHz will be out of range on a low band antenna.

 

[LongIslandHonker]

Thanks all for your replies, first: My application is upgrading my existing Icom R-75 & Vertex Standard VX-5500 monitoring post with Andrew 1/2" hardline feeding four 5/8th's wave commercial grade low band dipoles for the maximum ground wave effect, skip & tropospheric ducting is a plus but not essential, the antennas need to be cut for 33.64 MHz & 46.46 MHz respectively (Pretty much center of the 33.42 MHz to 33.98 MHz & 46.06 MHz to 46.5 MHz Fire Service bandplans) I've been keeping a sharp eye out for COM201B dipoles in mint condition tuned to 40 MHz as a cost savings factor for the R-75's, so far no good, I was informed that the Commscope DB201-L, Kathrein 717-758, Sinclair SG101, Kreco CP-40A & FGP-40A & Antenna Experts AG-50 antennas are 5/8th's wave over ground plane styles which I am unable to either confirm or deny at this time, either way those antennas utilize ground planes requiring longitudinal space requirements I cannot spare at my listening post, again thanks all & enjoy your weekend.

 

[prcguy]

If your interested in tropo ducting or skip you might look for a military surplus 30-76MHz log periodic. Used horizontal they will still have a fairly broad beam width of at least 45deg and some usable gain in the 4 to 6dB range. I had one of these but already gave it to another RR member: https://www.american-milspec.com/p-50-as-2236grc-dorne-margolin-log-perodic.aspx
prcguy

 

[ipfd320]

on the Skip / Tropospheric Ducting Forum KKN50 VHF Low Band Logs He is Using a G5RV DiPole-According to His Logs He has a Good Coverage for What You are Looking For-and There Cheap Too---DX Engineering and a Few Other Sites are a Good Start...Good Luck

 

[NDRADIONUT]

You could make some big j poles out of copper pipe...

 

[cmdrwill]

The OP is wanting to copy Public Safety radio which IS vertical polarization.

 

[SCPD]

Try https://fmbroadcastantenna.com/index.html they would probably build you one. the have a stock 6 meter antenna. As for the 33 mhz you could probably take a Super Penetrator CB antenna and shorten it, that's what forest service here used to do for 31 mhz. But of course these are groundplanes

 

[wa1nic]

I've never done exactly what you want to do, but I have made broadband dipoles by paralleling two wires of slightly different lengths.

If I was going to improvise an antenna like what you need, to start with, I would stay away from 5/8 wave as it would be harder to do an the extra gain isnt all that much.

I would stuff several 12 gauge insulated wires of different lengths ranging from 1/4 wave at 30 to 1/4 wave at 50 Mhz inside a PVC pipe, and make a ground plane for it that was good for the lowest frequency (around 8 feet?).

 

[cmdrwill]

We actually had a commercial ground plane antenna that has two elements one for 47 and the other was for 6 meters. Worked very well.

 

[Project25_MASTR]

We actually had a commercial ground plane antenna that has two elements one for 47 and the other was for 6 meters. Worked very well.

I could see using two open dipoles and either a diplexer and/or Motorola's diplexing chart.

 

[wa1nic]

Feed them from the same point and no diplexer is needed. each one will take whatever current it is willing to accept based on it's impedance at a given frequency.

 

[LongIslandHonker]

Sorry all for my delayed response, I've been busy taking ARC disaster training courses for the upcoming hurricane season which NOAA has tentatively predicted four (4) count em (four) fairly dangerous hurricanes. The VX-5500's have been upgraded & are receiving ground wave signals quite satisfactory, no skip yet but that's a bonus if it comes. The R-75 setup needs more work antenna wise, I am going to attempt a DIY wideband trap vertical dipole like the hams have on HF with 10, 15, 20 & 40 meter style traps, again thanks all for your very informative replies & have a very happy & safe Memorial Day .

 

[scottyhetzel]

Laird makes a 5/8 wide band vhf low made specifically for the California highway patrol. 39-45 MHz in black with a spring...pricey antenna.

 

[Karl-NVW]

He's looking for a base station antenna, not a mobile.