Yagi question!

[w4wxp]

Was thinking about getting a PCtel 12 element UHF yagi for listening to distant GMRS and 70cm Repeaters, etc. on an SDRplay.

I'm guessing that (as it's only for receive purposes) it'd also be usable on the VHF portion of the spectrum as well as doing a bit of FM Broadcast DX Listening with some decent gain.

Any ideas what kind of receive radiation pattern / beamwidth etc a UHF yagi of that caliber would have on VHF and the FM BCB?

 

[mmckenna]

A UHF Yagi is not going to work well on VHF. The measurements will be all way off and that will impact performance.

If you want FM broadcast DXing capability, get an old TV antenna, or build a dedicated Yagi for the band. Building a simple Yagi isn't hard.

 

[prcguy]

A UHF Yagi will not work at all on VHF, or not any better than about 6" of coat hanger wire sticking up in the air. I take that back, At VHF, a UHF Yagi will work worse than 6" of wire sticking up in the air. Not only will it not have any decent gain for VHF or FM broadcast DX, it will have considerable loss compared to a 1/4 wave ground plane.

A Yagi works at a very specific frequency plus or minus some small percentage. At UHF a typical Yagi can have up to about 20MHz of band width and any gain and useable patterns start dropping off quite rapidly outside its design range.

 

[jwt873]

You can buy dual band Yagi antennas for 2m/70cm.. Here's one --> Hy-Gain DB-2345 Dual Band Yagi, 3/5 Element, 144/440

Not as much gain as a single 12 element, but for the trade-off, you'll get good performance on both bands.

 

[w4wxp]

I guess I could always just build an array of Rhombic Antennas in the cardinal directions...

 

[iMONITOR]

Create CLP-5130-2N Log Periodic Antenna

https://www.theantennafarm.com/catalog/index.php?main_page=product_info&products_id=3389

 

[merlin]

Better off with a VHF Yagi. Vhf is poor on a UHF antenna. UHF on a VHF Yagi works OK but nothing of the gain you would have with dedicated antennas and switch.
FM broadcast DX, buy or roll your own 3 element Yagi and maybe an RCA rotator.
Receiving VHF, UHF, FMbc, an older log periodic type TV antenna and a preamp, you will hear any signals that are getting to you.

Classic Series Yagi YA7000C | Winegard Company

winegard.com

Hey, don't be fooled with this miles of range stuff, if a signal is reaching you, you get it, irregardless of range.
No such thing as a digital TV antenna either,,RF emission is analog,period.
73s

 

[merlin]

Create CLP-5130-2N Log Periodic Antenna

https://www.theantennafarm.com/catalog/index.php?main_page=product_info&products_id=3389

View attachment 104138View attachment 104139

Decent, but more expensive than the SDRplay and a Winegard TV antenna.