70cm halfwave

Pete_uk · #1 (**permalink**) 01-26-2013, 12:27 PM

Hi all

Does anyone know if there is a good halfwave antenna for 70cm on the market? I have a couple of roughly 12inch rubber duckies but I'm not sure how they work in terms of radiation pattern etc.

It would be nice to have a dualband antenna but as my local (11 miles) 70cm repeater is the nearest, 70cm performance is more important.

Any ideas welcome.

LtDoc · #2 (**permalink**) 01-26-2013, 7:02 PM

I'm not aware of any "1/2 wave" 70 cm antennas. There are a number of 70 cm vertical 'array' type antennas on the market. I would think one of them should do at least as well as a strictly '1/2 wave' antenna. Biggest problem would be in the impedance matching for that 1/2 wave, I'd think.
- 'Doc

N1BHH · #3 (**permalink**) 01-26-2013, 8:10 PM

There are some mobile half wave and some 5/8 wave mobile antennas available, just do a search on the internet. But you're talking an HT antenna? Most duckies are half wave. Are you looking for a gain antenna? There are plenty put there, see all the ham radio supply houses, they all have them. You need to be more specific on your needs.

W2NJS · #4 (**permalink**) 01-27-2013, 8:58 AM

If your UHF duckie is 12 inches long it's a half-wave antenna. The nominal length of a UHF quarter-wave antenna is about 6 inches, so a half-wave is about 12 inches. The signal is fed up to the midpoint of the antenna where the coaxial cable's center conductor is connected to one half of the antenna and the coax shield is connected to the other half. Simple as that. A half-wave antenna is analogous to a horizontal, center-fed HF antenna for the low bands. It doesn't require a ground plane and that's its main advantage. The antenna you have should have some advantage over using a quarter-wave antenna on the HT.

AD5KO · #5 (**permalink**) 01-27-2013, 10:04 AM

Quote:

Originally Posted by Pete_uk

Hi all

Does anyone know if there is a good halfwave antenna for 70cm on the market? I have a couple of roughly 12inch rubber duckies but I'm not sure how they work in terms of radiation pattern etc.

It would be nice to have a dualband antenna but as my local (11 miles) 70cm repeater is the nearest, 70cm performance is more important.

Any ideas welcome.

As has already been pointed out a 12inch antenna is a halfwave on 70cm, but here is a link to some relatively high performance portable whips.
SRH SERIES/DIAMOND ANTENNA CORPORATION

I find the Diamond SRH-771 to be very good.

mm · #6 (**permalink**) 01-27-2013, 2:28 PM

Smiley antennas has a nice 5/8th wave ht model that
Works very fine and it is priced very reasonable.

Pete_uk · #7 (**permalink**) 01-29-2013, 5:45 AM

Thanks for the information. I had wondered what went on in some of the rubber ducks that are on the market.

cheers