# 4G LTE: Is it possible to make a high gain antenna that resonates well for two frequencies, where one isn't a close harmonic of the other?

I want a high gain antenna for Verizon LTE data to my JetPack 7730L but don't really see one as high as say this MIMO parabolic antenna that's probably design for 2.4 GHz WiFi. From all I know it's only possible to make an antenna that's turned well to one frequency but could also work at harmonics of that frequency like 1/4, 1/2, 5/8 (not sure of the gains for these).

For instance a 1/2 wavelength antenna for 2 GHz could also double as a 1/4 wavelength antenna for 1 GHz based on the equation...

$$\\lambda =\frac{c}{f}\$$

But is it possible to create an antenna that is tuned to a different frequency outside of the near natural harmonics? Like say

These frequencies I am interested... all the Verizon Wireless bands and I'm not sure if it's helpful at all the have the fraction of wavelength... but that's just the thought that first came to mind.

 Frequency   Fraction of Wavelength
-----------|------------------------
2100 MHz             1.00
1900 MHz             0.90
1700 MHz             0.81
850 MHz             0.40
700 MHz             0.33


PS: I'm not sure if all these frequencies are used for Verizon Wireless 4G LTE data, but at least these are frequencies they use in general.

• do you realize that you asked a question that has a yes or no answer? Jan 26 '20 at 19:48
• not all antennas are resonant at their operational frequencies, by the way. Jan 26 '20 at 19:59
• If you make a straight wire antenna, then indeed it can work at harmonics which will be close to integer ratios of the lowest frequency of operation. If an otherwise straight antenna of length x includes a lumped component of value y in series with it at position z, then you have three degrees of freedom, which can be used to adjust at least the second and possibly the third resonance independently of each other. Jan 27 '20 at 4:43

Yes, that's possible, and you'll find directive multi-band antennas commercially-off-the-shelf.

These internally mostly resemble Yagi-Uda antennas, but don't have the same director sizing as actual Yagi-Udas. Probably, they were designed starting as Yagi-Uda, and then stochastically optimized in simulation until they worked well enough on multiple frequencies.

So,

is it possible to make...

yes; whether or not it's possible for you depends on your willingness to learn how to simulate complicated antennas and your access to tools to build and to measurement chambers and costly measurement equipment to measure an antenna.

Really, buy a multi-band antenna. These exist.

• Thanks to your tips I am learning about "traps" in Yagi-Uda antenas where a well placed inductor and capacitor (LC) in the antenna can isolate parts of it at higher frequencies. People make dual and tri-band antennas this way. This lead me to learning about log pole (LP) and log pole dipole array (LPDA) antennas, which is not a yagi but appears like one at first glance. An LPDA is ideal for accommodating broad range of frequencies. Jan 29 '20 at 1:57
• yes, but a LPDA covers all of a large range and hence is a) less selective than you'd want, and b) larger than strictly necessary. Jan 29 '20 at 10:07

You might use a diplexor in the antenna feed. I believe such a construct will provide 2 output channels.

• This looks a lot more like a comment than an answer. Jan 27 '20 at 16:08
• This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review Jan 27 '20 at 16:08
• I disagree @Puffafish. This is a valid separate answer. This person provided a solution to my question is it possible to create an antenna that resonates at two frequencies. I didn't know about diplexers and that is very useful to know as you could get higher gain for targeted frequencies if a wide-spectrum antenna doesn't exist. I'm assuming there's essentially no signal attenuation when you do this? Jan 27 '20 at 18:38