Best Low Band Antenna

[mancow]

Don't make me come over there and install that thing for you.....
Get it up! Can't you just get it up?

Ooh, that didn't sound right. Oh what you people must think of me now........
prcguy

Shakin it here boss...

I'll figure something out.

 

[sparklehorse]

Hello again gent's, I've received a bunch of tropo/skip frequencies & WWV at 25 MHz is almost constant, I've received very little local stuff, mostly DOT & 6 meter nets, CB comes & goes too, has the band been open lately or is this stuff just some kind of anomaly since you guys say you can sit by a scanner for weeks & get not one peep? I'm pretty much hearing a few things about every other day or two especially in the afternoons, I've already ordered the BCT15X & Andrew 1/2" superflex heliax coax, the dipole is going to be constructed from the plans here. 6 Meter Repeater Antenna 1/2 Wave Coaxial Vertical Antenna Design

Radio Dog, how's your 6-meter dipole working out? I've also been trying to improve my lo-band reception. I've been getting pretty good results from a rectangular wire loop antenna I built mostly out of stuff I had lying around the house: insulated 14 gauge solid copper wire, 3/4 inch PVC pipe, RG8x coax, and some para cord to suspend it from my 30' metal mast. The idea came from misterpaul71 in this post from 2013:

http://forums.radioreference.com/bu...ild-antenna-specific-vhf-low.html#post2072802

I made mine a full wavelength at 37 MHz, about 4.5 feet wide by 9 feet tall, and have it suspended so the bottom is about a half wavelength above the ground. It's working well. Still getting quite a bit of powerline noise though. I was hoping the horizontal polarity would help with that, but the noise improvement is minimal. Still, it works a lot better for lo-band than my AntennaCraft ST2. And the big surprise to me is that it's not terrible as a multi-band antenna. In fact it's actually pretty respectable for VHF-Hi Public Safety band. It's just OK for UHF and 800 MHz, and not great for VHF Air, but I'm surprised it works as well as it does in those bands given how far out of band it's cut. Also that it's polarity is horizontal, but perhaps when it's that far off frequency its polarity is less well defined?

Anyway, it was cheap and easy to make, and I'm enjoying it quite a lot. Thought I'd throw it out there as food for thought.

.

 

[Scannerfan15]

If cost and size are not concerns, I would go with a 30 - 88 MHz Log Periodic.

Does anybody know were I can buy one surplus?

 

[prcguy]

They show up on Ebay on rare occasion but here is one that has been for sale for several years and the guy might take less: https://www.american-milspec.com/p-50-as-2236grc-dorne-margolin-log-perodic.aspx

Its a stressed log periodic made of wires stretched across fiberglass spreaders. It covers 30 to 76MHz with around 4.5dB gain. I had one but never used it and now another RR member has it and we're waiting for a report on how well it works. How bout it Mr. new owner, how does it work?
prcguy

 

[SpectrumAnalyzer]

Pretty Interesting Setup

Radio Dog, how's your 6-meter dipole working out? I've also been trying to improve my lo-band reception. I've been getting pretty good results from a rectangular wire loop antenna I built mostly out of stuff I had lying around the house: insulated 14 gauge solid copper wire, 3/4 inch PVC pipe, RG8x coax, and some para cord to suspend it from my 30' metal mast. The idea came from misterpaul71 in this post from 2013:

http://forums.radioreference.com/bu...ild-antenna-specific-vhf-low.html#post2072802

I made mine a full wavelength at 37 MHz, about 4.5 feet wide by 9 feet tall, and have it suspended so the bottom is about a half wavelength above the ground. It's working well. Still getting quite a bit of powerline noise though. I was hoping the horizontal polarity would help with that, but the noise improvement is minimal. Still, it works a lot better for lo-band than my AntennaCraft ST2. And the big surprise to me is that it's not terrible as a multi-band antenna. In fact it's actually pretty respectable for VHF-Hi Public Safety band. It's just OK for UHF and 800 MHz, and not great for VHF Air, but I'm surprised it works as well as it does in those bands given how far out of band it's cut. Also that it's polarity is horizontal, but perhaps when it's that far off frequency its polarity is less well defined?

Anyway, it was cheap and easy to make, and I'm enjoying it quite a lot. Thought I'd throw it out there as food for thought.

.

Sparklehorse, could you provide the exact dimensions for your antenna, sounds interesting, is it directional? I really would like to get back into low band monitoring for the next couple of years & move on from this prohibitively expensive DC to daylight venture with all this digital this & that, P25 phase 1 & 2 FDMA, TDMA, NXDN, DMR, trunking, encryption, etc, I think I'll just pass this junk on to my grandson who's totally engrossed in radio right now & good for him, it's all starting to feel like work to me now & after cutting my teeth on low band monitoring then moving up to scanning signals of all types on all bands for 58 years it's time for me to get back to the basics again & enjoy this hobby the way it was meant for me, getting a CB radio too, go figure, everybody please have an enjoyable weekend & happy monitoring.

 

[sparklehorse]

Sparklehorse, could you provide the exact dimensions for your antenna, sounds interesting, is it directional? I really would like to get back into low band monitoring for the next couple of years & move on from this prohibitively expensive DC to daylight venture with all this digital this & that, P25 phase 1 & 2 FDMA, TDMA, NXDN, DMR, trunking, encryption, etc, I think I'll just pass this junk on to my grandson who's totally engrossed in radio right now & good for him, it's all starting to feel like work to me now & after cutting my teeth on low band monitoring then moving up to scanning signals of all types on all bands for 58 years it's time for me to get back to the basics again & enjoy this hobby the way it was meant for me, getting a CB radio too, go figure, everybody please have an enjoyable weekend & happy monitoring.

It's 4.5 ft wide x 9 ft tall. The 1:2 aspect ratio seems to be important for this type of loop. Feedpoint is the center of the bottom leg. At first I just cut a hole in the PVC, pulled an inch or so of each end of the loop thru the hole, then soldered the center lead of some old RG8X to one end, and the braid to the other end. Used plenty of electrical tape to insulate the two connection points from each other. That all worked well, but I went back later and made a better feed point using a Budwig HQ-1 connector, some LMR-400 Ultraflex, and a larger diameter piece of PVC in a Tee shape to house the Budwig in. Sealed that up with coax seal. I have end caps on the ends of the bottom piece of PVC with a small hole drilled for the wire to enter thru, then sealed the hole with coax seal. The idea being just to keep all water out of the bottom run of PVC. I switched to LMR-400 hoping it would improve 800 MHz performance but it didn't. If all you're interested in is lo-band RG8X should be fine unless the coax run is really long. I guess PVC degrades with exposure to UV, so I'll probably paint it someday.

.

 

[pearock1]

CHP 39-42 MHz

I presently have a discone antenna which is working great for most of the frequencies i scan except the CHP which run 39- 42 MHz. Just looking for a little advice on a low cost antenna for these frequencies.

 

[BushDoctor]

my low band antenna for 39.5 mhz

I presently have a discone antenna which is working great for most of the frequencies i scan except the CHP which run 39- 42 MHz. Just looking for a little advice on a low cost antenna for these frequencies.

i made a quad suppose to be 76 inches on each of the four sides i had to settle for 75 inches on each of the 4 sides fed on either of the vertical sides midway up (i chose the right side close to my scanner) to make it a vertical fed works great even down to 29.6 and 33.86 Mhz as well as 30.45 on skip from Texas to Virginia up through the 42 Mhz band for NC,MO, and CHP on skip. The antenna is inside around a 2 bay window with vertical supports on the right top and middle top and left top using the wooden dowels from wood pants hangers running through rubber bands at the top right and left and center the center just standing there by itself the right and left dowel bottoms secured to dual curtain rods with about 6 rubber bands each side securing the bottom of the dowels to the curtain rods above and below the rod making a spacing on the dowel of about 2 or 3 inches works fine for me and lots better then a vertical one in the corner of my room. I added a switch half way up the vertical left side which i can open for other freqs such as FM broadcast band.

 

[KJ6NWU]

A tuneable magnetic loop is easy to build and makes a great indoor antenna for monitoring.
For receive-only antennas, 75 ohm cable is going to give you an advantage over 50 ohm cable.

 

[wbswetnam]

Just for fun (because there's very little VHF-low band in my area), I made a cheap off-center fed dipole ("OCFD") cut for 40 MHz using a plastic coat hanger, a 300 ohm / 50 ohm TV matching transformer, and wire legs (longer element 7' 4", shorter element 4' 4"), with an F-connector male to SO-239 female adapter attached to the matching transformer. I strung it up into an inverted "V" pattern from a tree branch and took some measurements with the antenna analyzer. I had SWR readings between 1.1:1 and 1.6:1 across the entire VHF-low band spectrum, very good. Next I attached the antenna to a scanner and listened for a few minutes. I didn't hear anything on VHF-low band (again, none in my area) but it performed well on VHF-high and acceptably well on UHF. For a cheap VHF-low antenna, you could try an OCFD as I described here.

 

[Alain]

"The other issue is that ship is either working or its not. When its working you'll pick it up with a simple antenna. When its not, it doesn't matter what kind of antenna you have."

To assist in concluding "when it is and when it isn't", have you heard of Bill Hepburn's websites?

This is the one for tropo: Tropospheric Ducting Forecast for VHF & UHF Radio & TV

You might also purchasing a book by Gordon West, WB6NOA & Ken Neubeck, WB2AMU entitled, "VHF Propagation". It's available from CQ Magazine. Mine came with an accompanying CD that augments the written with audio. Great read!

I know that the above site and the book do NOT specifically address the 30 - 50 Mhz swatch; in my early days, I had great success just watching the weather reports for "inversions". I have used Hepburn's site for my VHF/UHF simplex "contesting" and it has worked very well for me. I recommend it highly.

Hope this helps.

Alain

 

[kb4cvn]

Lowband Base Antenna

Figured I will offer my humble 2¢ worth on this topic.


For 10m and 6m amateur comms, I have used Ringo Rangers for over 40 years.

Ditto on my Part-90 Freq on 29.790, I use a Ringo.

For specific frequency listening, 1/4-wavelength ground plane antennas can't be beat for low cost and simplicity. Usually built-up from CB antenna parts.


For broadband listening, I have used for over a decade with excellent results a Mil Surplus antenna I got from Sportsman's Guide:

M1921-101011, Högantenn 1; Swedish Military Surplus vhf-lowband discone antenna, 30-78 MHz.

I have successfully used this antenna on 14, 21, 24 & 28/29 MHz for transmitting on Amateur Radio while camping. All I did was rearrange the elements to add length.


I translated the manual from Swedish over into English back in 2005, and have attached it to this posting. You still see them for sale on occasion. I found all of mine for $65/each.