Is this kinda antenna I want even exist?

[KPMDWhistler]

Is there a high gain antenna like a yagi or other that can go from 118-400 MHz? I already have a 25-1300 discone, but I want something with a more direct fov. I mainly listen to 118-400 MHz that comes from a military base, and I would mount said high gain antenna (that probably doesn't exist) on a mast with direct line of sight to the base.

 

[mmckenna]

You want a log-periodic antenna.

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Or, you could try and old TV antenna turned so the elements are vertical.

 

[prcguy]

Yup, lots of different Log Periodic antennas out there what would fill the need. There is a smaller Create Log Periodic that covers about 100MHz to 1300MHz that will end mount vertically on a mast. Those don't have a ton of gain but probably 5-6dB more than a Discone. Military surplus Log Periodics occasionally show up on eBay for good prices. I picked up a nice Racal 100MHz to 1GHz portable version for $100 and an Italian 130 to 1300MHz version for less than $50 plus several others.

 

[dlwtrunked]

One always has to chose between gain, bandwidth, and somewhat omni-directionality (if you want that). You can never get all three.. A discone gives you bandwidth and omni-directionality. A log periodic gives you bandwidth but gain is not that great and you lose omni-directionality. A beam gives you gain, but you lose on omni-directionality. In your case, in your case, antenna height is they key thing. Not much you can do with too much near ground structures like hills, buildings, etc. in the way with any antenna type. Keep in mind that a fraction of a watt is easily heard from a weather balloon 50 miles away with nothing special for an antenna.