How to Add a Mastodon Hashtag to a Specific Antenna List

Mastodon antennas let you filter your home timeline by keywords, users, or hashtags. You might want to track a specific hashtag without cluttering your main feed. This article explains how antennas work and how to add a hashtag to an existing antenna list.

Antennas are part of Mastodon’s advanced filtering system. They are available on most instances running Mastodon 4.0 or later. Adding a hashtag to an antenna lets you see all public posts containing that tag in a dedicated column.

You will learn the exact steps to create or edit an antenna, add a hashtag rule, and verify the antenna is working. The process takes less than two minutes once you know where to click.

How Mastodon Antennas Work for Hashtag Filtering

Mastodon antennas are custom filters that create a separate feed for posts matching specific criteria. You define rules based on keywords, users, or hashtags. When a new public post matches any of your rules, it appears in the antenna column on your home screen.

Antennas are different from simple hashtag follows. Following a hashtag adds its posts to your home timeline. An antenna collects posts from multiple hashtags or sources into one dedicated column. This keeps your main feed uncluttered while still letting you monitor topics like #technews or #photography.

Each antenna can have multiple rules. You can mix hashtag rules with keyword rules and user rules in the same antenna. For example, you can create an antenna that shows posts containing #MastodonTips OR posts from a specific user. This flexibility makes antennas useful for tracking events, communities, or breaking news.

Prerequisites for Using Antennas

Before you add a hashtag to an antenna, confirm that your Mastodon instance supports antennas. Most instances running Mastodon 4.0 or newer have them. You can check by opening Preferences and looking for the Antennas section. If you do not see it, contact your instance admin or check the instance changelog.

You also need a Mastodon account on that instance. Antennas are personal settings. They do not affect other users on the same instance.

Steps to Add a Hashtag to an Antenna List

Follow these steps to add a hashtag to an existing antenna or create a new antenna with a hashtag rule.

1. Open Mastodon Preferences
   Click the gear icon in the bottom-left corner of the web interface. On mobile, tap the hamburger menu and then tap Preferences.
2. Navigate to the Antennas Section
   In the left sidebar, click Antennas under the Filters group. If you do not see it, look for a section named Antennas or Advanced Filters.
3. Select an Existing Antenna or Create a New One
   To edit an existing antenna, click its name in the list. To create a new antenna, click the Add Antenna button at the top of the page. A form appears with fields for Name, Visibility, and Rules.
4. Name the Antenna
   In the Name field, type a descriptive name. For example, type Technology News if you plan to track #tech. Use a name that helps you remember the antenna’s purpose.
5. Set Antenna Visibility
   Choose whether the antenna column is visible to you only or to other users on your instance. Public antennas can be seen by anyone who views your profile. Private antennas are only visible to you.
6. Add a Hashtag Rule
   Under the Rules section, click the Add Rule button. A new row appears. From the dropdown menu, select Hashtag. In the text field next to it, type the hashtag without the # symbol. For example, type MastodonTips to track #MastodonTips.
7. Add More Rules if Needed
   You can add multiple rules to the same antenna. Click Add Rule again and choose another hashtag or a different rule type such as Keyword or User. The antenna shows posts that match any of the rules.
8. Save the Antenna
   Click the Save button at the bottom of the form. Mastodon saves the antenna and creates a new column on your home screen. The column title matches the antenna name you entered.
9. Verify the Antenna Is Working
   Go back to your home screen. Look for the new column with the antenna name. If no posts appear yet, wait a few minutes for new posts containing the hashtag to be published. You can also test by posting a public post with the hashtag from another account and checking if it shows up.

Common Mistakes and Limitations When Adding Hashtags to Antennas

Hashtag Rule Does Not Show Any Posts

If your antenna column stays empty, check the following:

• You typed the hashtag without the # symbol. The rule field expects only the tag name, not the full hashtag.
• The hashtag is case-sensitive in the rule. Mastodon treats TechNews and technews as different tags. Use the exact casing you want to match.
• No public posts with that hashtag have been published since you created the antenna. Antennas only show new posts, not historical ones. Wait for fresh posts to appear.

Antenna Column Not Visible on the Home Screen

If you saved the antenna but do not see the column, refresh your browser or restart the Mastodon mobile app. On the web interface, you can also collapse and expand the sidebar to force a refresh. If the column still does not appear, check that you did not accidentally set the antenna visibility to Public and then hide it from yourself. Private antennas are always visible to you.

Cannot Edit or Delete an Antenna

To edit an antenna, go back to Preferences > Antennas and click the antenna name. To delete it, click the Delete button next to the antenna name in the list. Deletion is permanent and cannot be undone. The antenna column disappears from your home screen immediately.

Antenna Rules Are Not Applied to Existing Posts

Antennas only show posts created after the antenna is saved. They do not retroactively scan your instance’s public timeline for older posts. If you need to see older posts, use the search feature with the hashtag instead. This is a design limitation of the antenna system.

Antenna vs Simple Hashtag Follow: Which to Use

Item	Antenna with Hashtag Rule	Simple Hashtag Follow
Description	Dedicated column showing posts from multiple hashtags or sources	Adds posts with one hashtag directly to your home timeline
Visibility	Can be private or public	Always public on your profile
Multiple sources	Yes, combine hashtags, keywords, and users in one column	No, only one hashtag per follow
Impact on home timeline	No impact, posts appear in a separate column	Directly adds posts to your home timeline
Retroactive	No, only shows new posts after creation	No, only shows new posts after following

Use an antenna when you want to monitor a topic without cluttering your home timeline. Use a simple hashtag follow when you want the hashtag’s posts to appear alongside your regular feed.

You can now add any hashtag to a Mastodon antenna and keep your home timeline organized. Try creating an antenna for a conference hashtag or a community tag you follow regularly. For advanced use, combine hashtag rules with keyword rules to exclude posts that contain certain words, which you can do by adding a negative keyword rule if your instance supports it.